De Wikipedia, la enciclopedia libre
Saltar a navegación Saltar a búsqueda

Características generales de un gran ecosistema marino (Golfo de Alaska)
Las orcas ( orca ) son depredadores marinos muy visibles que cazan muchas especies grandes. Pero la mayor parte de la actividad biológica en el océano tiene lugar entre organismos marinos microscópicos que no se pueden ver individualmente a simple vista, como las bacterias marinas y el fitoplancton . [1]

La vida marina , o la vida marina o la vida oceánica , son las plantas , animales y otros organismos que viven en el agua salada del mar o el océano, o en el agua salobre de los estuarios costeros . A un nivel fundamental, la vida marina afecta la naturaleza del planeta. Los organismos marinos, en su mayoría microorganismos , producen oxígeno y secuestran carbono . Las costas están en parte moldeadas y protegidas por la vida marina, y algunos organismos marinos incluso ayudan a crear nuevas tierras. El término marino proviene del latín mare, que significa mar u océano.

La mayoría de las formas de vida evolucionaron inicialmente en hábitats marinos . Por volumen, los océanos proporcionan alrededor del 90 por ciento del espacio vital del planeta. [2] Los primeros vertebrados aparecieron en forma de peces , [3] que viven exclusivamente en el agua. Algunos de estos evolucionaron hasta convertirse en anfibios que pasan parte de su vida en el agua y parte en la tierra. Otros peces evolucionaron hasta convertirse en mamíferos terrestres y posteriormente regresaron al océano como focas , delfines o ballenas . Las formas de plantas como las algas y las algas crecen en el agua y son la base de algunos ecosistemas submarinos. Planctonconstituye la base general de la cadena alimentaria oceánica , en particular el fitoplancton, que son los principales productores primarios .

Los invertebrados marinos exhiben una amplia gama de modificaciones para sobrevivir en aguas poco oxigenadas, incluidos los tubos de respiración como en los sifones de moluscos . Los peces tienen branquias en lugar de pulmones , aunque algunas especies de peces, como el pez pulmonado , tienen ambas. Los mamíferos marinos , como delfines, ballenas, nutrias y focas, necesitan salir a la superficie periódicamente para respirar aire.

Hay más de 200.000 especies marinas documentadas con quizás dos millones de especies marinas aún por documentar. [4] Las especies marinas varían en tamaño desde lo microscópico, incluido el fitoplancton, que puede ser tan pequeño como 0.02 micrómetros, hasta enormes cetáceos (ballenas, delfines y marsopas), incluida la ballena azul , el animal más grande conocido que alcanza los 33 metros (108 pies). en longitud. [5] [6] Se ha estimado que los microorganismos marinos , incluidos protistas , bacterias y virus , constituyen aproximadamente el 70%  [7] o aproximadamente el 90%  [8] [1]de la biomasa marina total . La vida marina se estudia científicamente tanto en biología marina como en oceanografía biológica .

Agua [ editar ]

Histograma de elevación que muestra el porcentaje de la superficie terrestre por encima y por debajo del nivel del mar.

No hay vida sin agua. [9] Ha sido descrito como el solvente universal por su capacidad para disolver muchas sustancias, [10] [11] y como el solvente de la vida . [12] El agua es la única sustancia común que existe como sólido , líquido y gas en condiciones normales para la vida en la Tierra. [13] El Premio Nobel ganador Albert Szent-Györgyi se refiere al agua como el mater und matriz : la madre y el vientre de la vida. [14]

La abundancia de agua superficial en la Tierra es una característica única del Sistema Solar . La hidrosfera de la Tierra está formada principalmente por océanos, pero técnicamente incluye todas las superficies de agua del mundo, incluidos mares interiores, lagos, ríos y aguas subterráneas hasta una profundidad de 2000 metros (6600 pies) .La ubicación submarina más profunda es Challenger Deep of the Mariana. Trinchera en el Océano Pacífico , con una profundidad de 10,900 metros (6,8 millas). [nota 1] [15]

Convencionalmente, el planeta se divide en cinco océanos separados, pero todos estos océanos se conectan en un solo océano mundial . [16] La masa de este océano mundial es de 1,35 × 10 18  toneladas métricas , o aproximadamente 1/4400 de la masa total de la Tierra. El océano mundial cubre un área de3,618 × 10 8  kilometro 2 con una profundidad media de3682 m , resultando en un volumen estimado de1.332 × 10 9  km 3 . [17] Si toda la superficie de la corteza terrestre estuviera a la misma elevación que una esfera lisa, la profundidad del océano mundial resultante sería de aproximadamente 2,7 kilómetros (1,7 millas). [18] [19]

El ciclo del agua de la Tierra

Aproximadamente el 97,5% del agua de la Tierra es salina ; el 2,5% restante es agua dulce . La mayor parte del agua dulce, alrededor del 69%, está presente en forma de hielo en los casquetes polares y los glaciares . [20] La salinidad promedio de los océanos de la Tierra es de aproximadamente 35 gramos (1,2 oz) de sal por kilogramo de agua de mar (3,5% de sal). [21] La mayor parte de la sal en el océano proviene del desgaste y la erosión de las rocas en la tierra. [22] Algunas sales se liberan de la actividad volcánica o se extraen de rocas ígneas frías . [23]

Los océanos también son un reservorio de gases atmosféricos disueltos, que son esenciales para la supervivencia de muchas formas de vida acuática. [24] El agua de mar tiene una influencia importante en el clima mundial, y los océanos actúan como una gran reserva de calor . [25] Los cambios en la distribución de la temperatura oceánica pueden causar cambios climáticos significativos, como El Niño-Oscilación del Sur . [26]

Europa, la luna de Júpiter, puede tener un océano subterráneo que sustenta la vida .

En total, el océano ocupa el 71 por ciento de la superficie mundial, [2] con un promedio de casi 3,7 kilómetros (2,3 millas) de profundidad. [27] En volumen, el océano proporciona alrededor del 90 por ciento del espacio vital del planeta. [2] El escritor de ciencia ficción Arthur C. Clarke ha señalado que sería más apropiado referirse al planeta Tierra como planeta Océano. [28] [29]

Sin embargo, el agua se encuentra en otras partes del sistema solar. Europa , una de las lunas que orbitan alrededor de Júpiter , es un poco más pequeña que la luna de la Tierra . Existe una gran posibilidad de que exista un gran océano de agua salada debajo de su superficie de hielo. [30] Se ha estimado que la corteza exterior de hielo sólido tiene unos 10-30 km (6-19 millas) de espesor y el océano líquido que se encuentra debajo tiene unos 100 km (60 millas) de profundidad. [31] Esto haría que el océano de Europa tenga más del doble del volumen del océano de la Tierra. Se ha especulado que el océano de Europa podría albergar vida , [32] [33] y podría ser capaz de albergar microorganismos multicelulares si los respiraderos hidrotermalesestán activos en el fondo del océano. [34] Encelado , una pequeña luna helada de Saturno, también tiene lo que parece ser un océano subterráneo que ventila activamente agua caliente desde la superficie de la luna. [35]

Evolución [ editar ]

La Tierra tiene unos 4.540 millones de años. [36] [37] [38] La evidencia indiscutible más antigua de vida en la Tierra data de hace al menos 3.500 millones de años, [39] [40] durante la Era Eoarcaica después de que una corteza geológica comenzó a solidificarse después del Eón Hadeano fundido anterior . Se han encontrado fósiles de esteras microbianas en areniscas de 348 mil millones de años en Australia Occidental . [41] [42] Otra evidencia física temprana de una sustancia biogénica es el grafitoen rocas metasedimentarias de 3.700 millones de años descubiertas en el oeste de Groenlandia [43] , así como en "restos de vida biótica " encontrados en rocas de 4.100 millones de años en Australia Occidental. [44] [45] Según uno de los investigadores, "Si la vida surgiera relativamente rápido en la Tierra ... entonces podría ser común en el universo ". [44]

Todos los organismos de la Tierra descienden de un ancestro común o un acervo genético ancestral . [46] [47] Se cree que la química altamente energética produjo una molécula autorreplicante hace unos 4 mil millones de años, y quinientos millones de años después existió el último ancestro común de toda la vida . [48] El consenso científico actual es que la compleja bioquímica que constituye la vida proviene de reacciones químicas más simples. [49] El comienzo de la vida puede haber incluido moléculas autorreplicantes como el ARN [50] y el ensamblaje de células simples. [51] En 2016, los científicos informaron sobre un conjunto de 355 genesdel último ancestro común universal (LUCA) de toda la vida , incluidos los microorganismos, que viven en la Tierra . [52]

Las especies actuales son una etapa en el proceso de evolución, y su diversidad es producto de una larga serie de eventos de especiación y extinción. [53] La ascendencia común de los organismos se dedujo primero de cuatro hechos simples sobre los organismos: Primero, tienen distribuciones geográficas que no pueden explicarse por la adaptación local. En segundo lugar, la diversidad de la vida no es un conjunto de organismos completamente únicos, sino organismos que comparten similitudes morfológicas . En tercer lugar, los rasgos vestigiales sin un propósito claro se asemejan a los rasgos ancestrales funcionales y, finalmente, que los organismos pueden clasificarse utilizando estas similitudes en una jerarquía de grupos anidados, similar a un árbol genealógico. [54] Sin embargo, la investigación moderna ha sugerido que, debido a la transferencia horizontal de genes, este "árbol de la vida" puede ser más complicado que un simple árbol ramificado, ya que algunos genes se han propagado de forma independiente entre especies relacionadas lejanamente. [55] [56]

Las especies pasadas también han dejado registros de su historia evolutiva. Los fósiles, junto con la anatomía comparada de los organismos actuales, constituyen el registro morfológico o anatómico. [57] Al comparar las anatomías de especies modernas y extintas, los paleontólogos pueden inferir los linajes de esas especies. Sin embargo, este enfoque es más exitoso para organismos que tenían partes del cuerpo duras, como conchas, huesos o dientes. Además, como los procariotas, como las bacterias y las arqueas, comparten un conjunto limitado de morfologías comunes, sus fósiles no proporcionan información sobre su ascendencia.

EuryarchaeotaNanoarchaeotaCrenarchaeotaProtozoaAlgaePlantSlime moldsAnimalFungusGram-positive bacteriaChlamydiaeChloroflexiActinobacteriaPlanctomycetesSpirochaetesFusobacteriaCyanobacteriaThermophilesAcidobacteriaProteobacteria
Árbol evolutivo que muestra la divergencia de las especies modernas de su antepasado común en el centro. [58] Los tres dominios están coloreados, con bacterias azul, verde arqueas y rojo eucariotas .

Más recientemente, la evidencia de descendencia común proviene del estudio de similitudes bioquímicas entre organismos. Por ejemplo, todas las células vivas utilizan el mismo conjunto básico de nucleótidos y aminoácidos . [59] El desarrollo de la genética molecular ha revelado el registro de la evolución dejado en los genomas de los organismos: datación cuando las especies divergieron a través del reloj molecular producido por mutaciones. [60] Por ejemplo, estas comparaciones de secuencias de ADN han revelado que los humanos y los chimpancés comparten el 98% de sus genomas y analizar las pocas áreas en las que difieren ayuda a esclarecer cuándo existió el ancestro común de estas especies. [61]

Los procariotas habitaron la Tierra desde hace aproximadamente 3 a 4 mil millones de años. [62] [63] No se produjeron cambios obvios en la morfología o la organización celular en estos organismos durante los siguientes miles de millones de años. [64] Las células eucariotas surgieron hace entre 1.6 y 2.7 mil millones de años. El siguiente cambio importante en la estructura celular se produjo cuando las bacterias fueron engullidas por células eucariotas, en una asociación cooperativa llamada endosimbiosis . [65] [66] Las bacterias engullidas y la célula huésped luego experimentaron coevolución, y las bacterias evolucionaron hacia mitocondrias o hidrogenosomas . [67] Otro engullimiento de cianobacterias-como organismos llevaron a la formación de cloroplastos en algas y plantas. [68]

Árbol filogenético y simbiogenético de organismos vivos, que muestra una vista de los orígenes de eucariotas y procariotas.

La historia de la vida fue la de los eucariotas unicelulares , procariotas y arqueas hasta hace unos 610 millones de años cuando empezaron a aparecer organismos multicelulares en los océanos en el período ediacarano . [62] [69] La evolución de la multicelularidad ocurrió en múltiples eventos independientes, en organismos tan diversos como esponjas , algas pardas , cianobacterias , hongos limosos y mixobacterias . [70] En 2016, los científicos informaron que, hace unos 800 millones de años, un cambio genético menor en una sola molécula llamada GK-PIDpuede haber permitido que los organismos pasaran de un organismo de una sola célula a una de muchas células. [71]

Poco después de la aparición de estos primeros organismos multicelulares, apareció una cantidad notable de diversidad biológica en un lapso de aproximadamente 10 millones de años, en un evento llamado explosión cámbrica . Aquí, la mayoría de los tipos de animales modernos aparecieron en el registro fósil, así como linajes únicos que posteriormente se extinguieron. [72] Se han propuesto varios factores desencadenantes de la explosión cámbrica, incluida la acumulación de oxígeno en la atmósfera a partir de la fotosíntesis. [73]

Hace unos 500 millones de años, las plantas y los hongos comenzaron a colonizar la tierra. La evidencia de la aparición de las primeras plantas terrestres se produce en el Ordovícico , hace unos 450  millones de años , en forma de esporas fósiles. [74] Las plantas terrestres comenzaron a diversificarse en el Silúrico tardío , desde hace unos 430  millones de años . [75] La colonización de la tierra por plantas pronto fue seguida por artrópodos y otros animales. [76] Los insectos fueron particularmente exitosos e incluso hoy en día constituyen la mayoría de las especies animales. [77] Anfibiosapareció por primera vez hace unos 364 millones de años, seguido por los primeros amniotas y aves hace unos 155 millones de años (ambos de linajes similares a los " reptiles "), los mamíferos hace unos 129 millones de años, los homínidos hace unos 10 millones de años y los humanos modernos hace unos 250.000 años . [78] [79] [80] Sin embargo, a pesar de la evolución de estos animales grandes, los organismos más pequeños similares a los tipos que evolucionaron temprano en este proceso continúan teniendo mucho éxito y dominan la Tierra, con la mayoría de la biomasa y las especies siendo procariotas. [81]

Las estimaciones sobre el número de especies actuales de la Tierra oscilan entre 10 y 14 millones, [82] de las cuales se han documentado alrededor de 1,2 millones y más del 86 por ciento aún no se han descrito. [83]

Microorganismos [ editar ]

esteras microbianas
Los estromatolitos se forman a partir de esteras microbianas a medida que los microbios se mueven lentamente hacia arriba para evitar ser asfixiados por los sedimentos.

Los microorganismos constituyen aproximadamente el 70% de la biomasa marina . [7] Un microorganismo , o microbio, es un organismo microscópico demasiado pequeño para ser reconocido a simple vista. Puede ser unicelular [84] o multicelular . Los microorganismos son diversos e incluyen todas las bacterias y arqueas , la mayoría de los protozoos como las algas , los hongos y ciertos animales microscópicos como los rotíferos .

Muchos animales y plantas macroscópicos tienen estadios juveniles microscópicos . Algunos microbiólogos también clasifican los virus (y viroides ) como microorganismos, pero otros los consideran no vivos. [85] [86]

Los microorganismos son cruciales para el reciclaje de nutrientes en los ecosistemas, ya que actúan como descomponedores . Algunos microorganismos son patógenos y causan enfermedades e incluso la muerte en plantas y animales. [87] Como habitantes del medio ambiente más grande de la Tierra, los sistemas marinos microbianos impulsan cambios en todos los sistemas globales. Los microbios son responsables de prácticamente toda la fotosíntesis que ocurre en el océano, así como del ciclo del carbono , nitrógeno , fósforo , otros nutrientes y oligoelementos. [88]

El rango de tamaños que muestran los procariotas (bacterias y arqueas) y virus en relación con los de otros organismos y biomoléculas.
Bucle microbiano marino

La vida microscópica submarina es diversa y aún no se comprende bien, por ejemplo, el papel de los virus en los ecosistemas marinos. [89] La mayoría de los virus marinos son bacteriófagos , que son inofensivos para las plantas y los animales, pero son esenciales para la regulación de los ecosistemas de agua dulce y salada. [90] Infectan y destruyen bacterias en comunidades microbianas acuáticas y son el mecanismo más importante de reciclaje de carbono en el medio marino. Las moléculas orgánicas liberadas por las células bacterianas muertas estimulan el crecimiento de algas y bacterias frescas. [91] La actividad viral también puede contribuir a la bomba biológica , el proceso por el cual el carbono sesecuestrado en las profundidades del océano. [92]

El aerosol marino que contiene microorganismos marinos puede ser arrastrado hacia la atmósfera donde se convierte en aeroplancton y puede viajar por el globo antes de volver a la tierra.
Bajo una lupa, un chorro de agua de mar rebosa de vida.

Una corriente de microorganismos transportados por el aire rodea el planeta por encima de los sistemas meteorológicos pero por debajo de las rutas aéreas comerciales. [93] Algunos microorganismos peripatéticos son arrastrados por las tormentas de polvo terrestres, pero la mayoría se origina a partir de microorganismos marinos en el rocío del mar . En 2018, los científicos informaron que cientos de millones de virus y decenas de millones de bacterias se depositan diariamente en cada metro cuadrado del planeta. [94] [95]

Los organismos microscópicos viven en toda la biosfera . La masa de microorganismos procariotas , que incluye bacterias y arqueas, pero no los microorganismos eucariotas nucleados , puede llegar a 0,8 billones de toneladas de carbono (de la masa total de la biosfera , estimada entre 1 y 4 billones de toneladas). [96] Se han encontrado microbios marinos barófilos unicelulares a una profundidad de 10.900 m (35.800 pies) en la Fosa de las Marianas , el lugar más profundo de los océanos de la Tierra. [97] [98] Los microorganismos viven dentro de las rocas a 580 m (1900 pies) por debajo del lecho marino bajo 2590 m (8500 pies) de océano frente a la costa del noroeste de los Estados Unidos,[97] [99] así como 2.400 m (7.900 pies; 1,5 millas) por debajo del lecho marino frente a Japón. [100] La temperatura más alta conocida a la que puede existir vida microbiana es 122 ° C (252 ° F) ( Methanopyrus kandleri ). [101] En 2014, los científicos confirmaron la existencia de microorganismos que viven a 800 m (2.600 pies) por debajo del hielo de la Antártida . [102] [103] Según un investigador, "Puedes encontrar microbios en todas partes; son extremadamente adaptables a las condiciones y sobreviven donde sea que estén". [97]

Virus marinos [ editar ]

Los virus son pequeños agentes infecciosos que no tienen su propio metabolismo y solo pueden replicarse dentro de las células vivas de otros organismos . [104] Los virus pueden infectar todo tipo de formas de vida , desde animales y plantas hasta microorganismos , incluidas bacterias y arqueas . [105] El tamaño lineal del virus promedio es aproximadamente una centésima parte del de la bacteria promedio . La mayoría de los virus no se pueden ver con un microscopio óptico, por lo queEn su lugar, se utilizan microscopios electrónicos . [106]

Los virus se encuentran dondequiera que haya vida y probablemente han existido desde que las células vivas evolucionaron por primera vez. [107] El origen de los virus no está claro porque no forman fósiles, por lo que se han utilizado técnicas moleculares para comparar el ADN o ARN de los virus y son un medio útil para investigar cómo surgen. [108]

Los virus ahora se reconocen como antiguos y con orígenes anteriores a la divergencia de la vida en los tres dominios . [109] Pero los orígenes de los virus en la historia evolutiva de la vida no están claros: algunos pueden haber evolucionado a partir de plásmidos, piezas de ADN que pueden moverse entre las células, mientras que otros pueden haber evolucionado a partir de bacterias. En la evolución, los virus son un medio importante de transferencia horizontal de genes , lo que aumenta la diversidad genética . [110]

Bacteriófagos (fagos)
Múltiples fagos adheridos a una pared celular bacteriana con un aumento de 200,000x
Diagrama de un fago de cola típico
Estos son cianófagos , virus que infectan a las cianobacterias (las barras de escala indican 100 nm)

Las opiniones difieren sobre si los virus son una forma de vida o estructuras orgánicas que interactúan con los organismos vivos. [111] Algunos los consideran una forma de vida, porque portan material genético, se reproducen creando múltiples copias de sí mismos mediante el autoensamblaje y evolucionan a través de la selección natural . Sin embargo, carecen de características clave, como una estructura celular que generalmente se considera necesaria para contar como vida. Debido a que poseen algunas de esas cualidades, pero no todas, los virus se han descrito como replicadores [112] y como "organismos al borde de la vida". [113]

En términos de recuentos individuales, los fagos de cola son las entidades biológicas más abundantes en el mar.

Los bacteriófagos , a menudo llamados simplemente fagos , son virus que parasitan las bacterias y las arqueas. Los fagos marinos parasitan las bacterias y arqueas marinas, como las cianobacterias . [114] Son un grupo común y diverso de virus y son la entidad biológica más abundante en los ambientes marinos, porque sus huéspedes, las bacterias, son típicamente la vida celular numéricamente dominante en el mar. En general, hay alrededor de 1 millón a 10 millones de virus en cada ml de agua de mar, o aproximadamente diez veces más virus de ADN bicatenario que organismos celulares, [115] [116] aunque las estimaciones de la abundancia viral en el agua de mar pueden variar en un amplio distancia. [117][118] Los bacteriófagos de cola parecen dominar los ecosistemas marinos en número y diversidad de organismos. [114] También se sabe que losbacteriófagos pertenecientes a las familias Corticoviridae , [119] Inoviridae [120] y Microviridae [121] infectan diversas bacterias marinas.

Los microorganismos constituyen aproximadamente el 70% de la biomasa marina. [7] Se estima que los virus matan el 20% de esta biomasa cada día y que hay 15 veces más virus en los océanos que bacterias y arqueas. Los virus son los principales agentes responsables de la rápida destrucción de los dañinos proliferación de algas , [122] que a menudo matan a otras especies marinas. [123] El número de virus en los océanos disminuye más lejos de la costa y más profundamente en el agua, donde hay menos organismos hospedadores. [92]

También hay virus arqueos que se replican dentro de arqueas : estos son virus de ADN de doble cadena con formas inusuales y, a veces, únicas. [124] [125] Estos virus se han estudiado con más detalle en las arqueas termofílicas , en particular los órdenes Sulfolobales y Thermoproteales . [126]

Los virus son un medio natural importante de transferir genes entre diferentes especies, lo que aumenta la diversidad genética e impulsa la evolución. [110] Se cree que los virus jugaron un papel central en la evolución temprana, antes de la diversificación de bacterias, arqueas y eucariotas, en el momento del último ancestro común universal de la vida en la Tierra. [127] Los virus siguen siendo uno de los mayores reservorios de diversidad genética inexplorada en la Tierra. [92]

Bacterias marinas [ editar ]

Vibrio vulnificus , una bacteria virulenta que se encuentra en los estuarios y a lo largo de las zonas costeras.
Pelagibacter ubique , la bacteria más abundante en el océano, juega un papel importante en el ciclo global del carbono .

Las bacterias constituyen un gran dominio de microorganismos procarióticos . Por lo general, de unos pocos micrómetros de longitud, las bacterias tienen varias formas, que van desde esferas hasta varillas y espirales. Las bacterias estuvieron entre las primeras formas de vida que aparecieron en la Tierra y están presentes en la mayoría de sus hábitats . Las bacterias habitan suelo, agua, aguas termales ácidas , los residuos radiactivos , [128] y las porciones profundas de la corteza terrestre . Las bacterias también viven en relaciones simbióticas y parasitarias con plantas y animales.

Una vez consideradas plantas que constituyen la clase Schizomycetes , las bacterias ahora se clasifican como procariotas . A diferencia de las células de animales y otros eucariotas , las células bacterianas no contienen un núcleo y rara vez albergan orgánulos unidos a la membrana . Aunque el término bacteria incluía tradicionalmente a todos los procariotas, la clasificación científica cambió después del descubrimiento en la década de 1990 de que los procariotas consisten en dos grupos muy diferentes de organismos que evolucionaron a partir de un ancestro común antiguo. Estos dominios evolutivos se denominan bacterias yArchaea . [129]

Los antepasados ​​de las bacterias modernas fueron microorganismos unicelulares que fueron las primeras formas de vida que aparecieron en la Tierra, hace unos 4 mil millones de años. Durante unos 3.000 millones de años, la mayoría de los organismos fueron microscópicos y las bacterias y las arqueas fueron las formas de vida dominantes. [130] [131] Aunque existen fósiles bacterianos , como los estromatolitos , su falta de morfología distintiva impide que se utilicen para examinar la historia de la evolución bacteriana o para fechar el momento del origen de una especie bacteriana en particular. Sin embargo, las secuencias de genes se pueden utilizar para reconstruir la filogenia bacteriana., y estos estudios indican que las bacterias divergieron primero del linaje arqueal / eucariota. [132] Las bacterias también participaron en la segunda gran divergencia evolutiva, la de las arqueas y los eucariotas. Aquí, los eucariotas resultaron de la entrada de bacterias antiguas en asociaciones endosimbióticas con los antepasados ​​de las células eucariotas, que posiblemente estaban relacionadas con las arqueas . [66] [133] Esto implicó la absorción por las células protoeucariotas de simbiontes alfaproteobacterianos para formar mitocondrias o hidrogenosomas., que todavía se encuentran en todos los Eukarya conocidos. Más tarde, algunos eucariotas que ya contenían mitocondrias también engullieron organismos parecidos a las cianobacterias. Esto condujo a la formación de cloroplastos en algas y plantas. También hay algunas algas que se originaron incluso a partir de eventos endosimbióticos posteriores. Aquí, los eucariotas envolvieron un alga eucariota que se convirtió en un plastidio de "segunda generación". [134] [135] Esto se conoce como endosimbiosis secundaria .

  • La marina Thiomargarita namibiensis , la bacteria más grande conocida

  • Las floraciones de cianobacterias pueden contener cianotoxinas letales .

  • Los cloroplastos de los glaucófitos tienen una capa de peptidoglicano , evidencia que sugiere su origen endosimbiótico a partir de cianobacterias . [136]

  • Las bacterias pueden ser beneficiosas. Este gusano de Pompeya , un extremófilo que se encuentra solo en los respiraderos hidrotermales , tiene una cubierta protectora de bacterias.

La bacteria más grande conocida, la Thiomargarita namibiensis marina , puede ser visible a simple vista y en ocasiones alcanza 0,75 mm (750 μm). [137] [138]

Archaea marina [ editar ]

Inicialmente, las arqueas se consideraban extremófilos que vivían en entornos hostiles, como las arqueas amarillas que se muestran aquí en una fuente termal , pero desde entonces se han encontrado en una gama mucho más amplia de hábitats . [139]

Las arqueas (del griego antiguo [140] ) constituyen un dominio y reino de microorganismos unicelulares . Estos microbios son procariotas , lo que significa que no tienen núcleo celular ni ningún otro orgánulo unido a la membrana en sus células.

Las arqueas se clasificaron inicialmente como bacterias , pero esta clasificación está desactualizada. [141] Las células de Archaeal tienen propiedades únicas que las separan de los otros dos dominios de la vida, Bacteria y Eukaryota . Las arqueas se dividen además en múltiples filos reconocidos . La clasificación es difícil porque la mayoría no se han aislado en el laboratorio y solo se han detectado mediante el análisis de sus ácidos nucleicos en muestras de su entorno.

Las arqueas y las bacterias son generalmente similares en tamaño y forma, aunque algunas arqueas tienen formas muy extrañas, como las células planas y cuadradas de Haloquadratum walsbyi . [142] A pesar de esta similitud morfológica con las bacterias, las arqueas poseen genes y varias vías metabólicas que están más estrechamente relacionadas con las de los eucariotas, en particular las enzimas involucradas en la transcripción y traducción . Otros aspectos de la bioquímica de las arqueas son únicos, como su dependencia de los éter lípidos en sus membranas celulares , como los arqueoles.. Las arqueas utilizan más fuentes de energía que los eucariotas: estos van desde compuestos orgánicos , como azúcares, hasta amoníaco , iones metálicos o incluso gas hidrógeno . Las arqueas tolerantes a la sal (las Haloarchaea ) utilizan la luz solar como fuente de energía y otras especies de arqueas fijan el carbono ; sin embargo, a diferencia de las plantas y las cianobacterias , ninguna especie conocida de arqueas hace ambas cosas. Las arqueas se reproducen asexualmente por fisión binaria , fragmentación o gemación ; a diferencia de las bacterias y eucariotas, ninguna especie conocida forma esporas .

Las arqueas son particularmente numerosas en los océanos y las arqueas del plancton pueden ser uno de los grupos de organismos más abundantes del planeta. Las arqueas son una parte importante de la vida de la Tierra y pueden desempeñar un papel tanto en el ciclo del carbono como en el ciclo del nitrógeno .

  • Las halobacterias , que se encuentran en el agua casi saturada de sal, ahora se reconocen como arqueas.

  • Células planas y cuadradas de las arqueas Haloquadratum walsbyi

  • Methanosarcina barkeri , una arquea marina que produce metano

  • Los termófilos , como Pyrolobus fumarii , sobreviven bien por encima de los 100 ° C.

  • Dibujo de otro termófilo marino, Pyrococcus furiosus

Protistas marinos [ editar ]

Los protistas son eucariotas que no se pueden clasificar como plantas, hongos o animales. Suelen ser unicelulares y microscópicos. La vida se originó como procariotas unicelulares (bacterias y arqueas) y luego evolucionó a eucariotas más complejos . Los eucariotas son las formas de vida más desarrolladas conocidas como plantas, animales, hongos y protistas. El término protista se utilizó históricamente como un término de conveniencia para eucariotas que no pueden clasificarse estrictamente como plantas, animales u hongos. No forman parte de la cladística moderna, porque son parafiléticos (carecen de un ancestro común). Los protistas se pueden dividir en cuatro grupos dependiendo de si su nutrición es similar a una planta, a un animal, a un hongo, [143]o una mezcla de estos. [144]

micrograph
cell schematic
Choanoflagellates, unicellular "collared" flagellate protists, are thought to be the closest living relatives of the animals.[146]

Getting to know our single-celled ancestors - MicroCosmos

Protists are highly diverse organisms currently organised into 18 phyla, but are not easy to classify.[147][148] Studies have shown high protist diversity exists in oceans, deep sea-vents and river sediments, suggesting a large number of eukaryotic microbial communities have yet to be discovered.[149][150] There has been little research on mixotrophic protists, but recent studies in marine environments found mixotrophic protests contribute a significant part of the protist biomass.[145]

  • Single-celled and microscopic protists
  • Diatoms are a major algae group generating about 20% of world oxygen production.[151]

  • Diatoms have glass like cell walls made of silica and called frustules.[152]

  • Fossil diatom frustule from 32 to 40 mya

  • Radiolarian

  • Single-celled alga, Gephyrocapsa oceanica

  • Two dinoflagellates

  • Zooxanthellae is a photosynthetic algae that lives inside hosts like coral.

  • A single-celled ciliate with green zoochlorellae living inside endosymbiotically.

  • Euglenoid

  • This ciliate is digesting cyanobacteria. The cytostome or mouth is at the bottom right.

Play media
Video of a ciliate ingesting a diatom

In contrast to the cells of prokaryotes, the cells of eukaryotes are highly organised. Plants, animals and fungi are usually multi-celled and are typically macroscopic. Most protists are single-celled and microscopic. But there are exceptions. Some single-celled marine protists are macroscopic. Some marine slime molds have unique life cycles that involve switching between unicellular, colonial, and multicellular forms.[153] Other marine protist are neither single-celled nor microscopic, such as seaweed.

  • Macroscopic protists (see also unicellular macroalgae →)
  • The single-celled giant amoeba has up to 1000 nuclei and reaches lengths of 5 mm.

  • Gromia sphaerica is a large spherical testate amoeba which makes mud trails. Its diameter is up to 3.8 cm.[154]

  • Spiculosiphon oceana, a unicellular foraminiferan with an appearance and lifestyle that mimics a sponge, grows to 5 cm long.

  • The xenophyophore, another single-celled foraminiferan, lives in abyssal zones. It has a giant shell up to 20 cm across.[155]

  • Giant kelp, a brown algae, is not a true plant, yet it is multicellular and can grow to 50m.

Protists have been described as a taxonomic grab bag where anything that doesn't fit into one of the main biological kingdoms can be placed.[156] Some modern authors prefer to exclude multicellular organisms from the traditional definition of a protist, restricting protists to unicellular organisms.[157][158] This more constrained definition excludes seaweeds and slime molds.[159]

Marine microanimals[edit]

As juveniles, animals develop from microscopic stages, which can include spores, eggs and larvae. At least one microscopic animal group, the parasitic cnidarian Myxozoa, is unicellular in its adult form, and includes marine species. Other adult marine microanimals are multicellular. Microscopic adult arthropods are more commonly found inland in freshwater, but there are marine species as well. Microscopic adult marine crustaceans include some copepods, cladocera and tardigrades (water bears). Some marine nematodes and rotifers are also too small to be recognised with the naked eye, as are many loricifera, including the recently discovered anaerobic species that spend their lives in an anoxic environment.[160][161] Copepods contribute more to the secondary productivity and carbon sink of the world oceans than any other group of organisms.

  • Marine microanimals
  • Over 10,000 marine species are copepods, small, often microscopic crustaceans

  • Darkfield photo of a gastrotrich, a worm-like animal living between sediment particles

  • Armoured Pliciloricus enigmaticus, about 0.2 mm long, live in spaces between marine gravel.

  • Drawing of a tardigrade (water bear) on a grain of sand

  • Rotifers, usually 0.1–0.5 mm long, may look like protists but have many cells and belongs to the Animalia.

Fungi[edit]

Lichen on a rock in a marine splash zone. Lichens are mutualistic associations between a fungus and an alga or cyanobacterium.
A sea snail, Littoraria irrorata, covered in lichen. This snail farms intertidal ascomycetous fungi.

Over 1500 species of fungi are known from marine environments.[162] These are parasitic on marine algae or animals, or are saprobes feeding on dead organic matter from algae, corals, protozoan cysts, sea grasses, wood and other substrata.[163] Spores of many species have special appendages which facilitate attachment to the substratum.[164] Marine fungi can also be found in sea foam and around hydrothermal areas of the ocean.[165] A diverse range of unusual secondary metabolites is produced by marine fungi.[166]

Mycoplankton are saprotropic members of the plankton communities of marine and freshwater ecosystems.[167][168] They are composed of filamentous free-living fungi and yeasts associated with planktonic particles or phytoplankton.[169] Similar to bacterioplankton, these aquatic fungi play a significant role in heterotrophic mineralization and nutrient cycling.[170] Mycoplankton can be up to 20 mm in diameter and over 50 mm in length.[171]

A typical milliliter of seawater contains about 103 to 104 fungal cells.[172] This number is greater in coastal ecosystems and estuaries due to nutritional runoff from terrestrial communities. A higher diversity of mycoplankton is found around coasts and in surface waters down to 1000 metres, with a vertical profile that depends on how abundant phytoplankton is.[173][174] This profile changes between seasons due to changes in nutrient availability.[175] Marine fungi survive in a constant oxygen deficient environment, and therefore depend on oxygen diffusion by turbulence and oxygen generated by photosynthetic organisms.[176]

Marine fungi can be classified as:[176]

  • Lower fungi - adapted to marine habitats (zoosporic fungi, including mastigomycetes: oomycetes and chytridiomycetes)
  • Higher fungi - filamentous, modified to planktonic lifestyle (hyphomycetes, ascomycetes, basidiomycetes). Most mycoplankton species are higher fungi.[173]

Lichens are mutualistic associations between a fungus, usually an ascomycete, and an alga or a cyanobacterium. Several lichens are found in marine environments.[177] Many more occur in the splash zone, where they occupy different vertical zones depending on how tolerant they are to submersion.[178] Some lichens live a long time; one species has been dated at 8,600 years.[179] However their lifespan is difficult to measure because what defines the same lichen is not precise.[180] Lichens grow by vegetatively breaking off a piece, which may or may not be defined as the same lichen, and two lichens of different ages can merge, raising the issue of whether it is the same lichen.[180]

The sea snail Littoraria irrorata damages plants of Spartina in the sea marshes where it lives, which enables spores of intertidal ascomycetous fungi to colonise the plant. The snail then eats the fungal growth in preference to the grass itself.[181]

According to fossil records, fungi date back to the late Proterozoic era 900-570 million years ago. Fossil marine lichens 600 million years old have been discovered in China.[182] It has been hypothesized that mycoplankton evolved from terrestrial fungi, likely in the Paleozoic era (390 million years ago).[183]

Origin of animals[edit]

Dickinsonia may be the earliest animal. They appear in the fossil record 571 million to 541 million years ago.

The earliest animals were marine invertebrates, that is, vertebrates came later. Animals are multicellular eukaryotes,[note 2] and are distinguished from plants, algae, and fungi by lacking cell walls.[184] Marine invertebrates are animals that inhabit a marine environment apart from the vertebrate members of the chordate phylum; invertebrates lack a vertebral column. Some have evolved a shell or a hard exoskeleton.

The earliest animal fossils may belong to the genus Dickinsonia,[185] 571 million to 541 million years ago.[186] Individual Dickinsonia typically resemble a bilaterally symmetrical ribbed oval. They kept growing until they were covered with sediment or otherwise killed,[187] and spent most of their lives with their bodies firmly anchored to the sediment.[188] Their taxonomic affinities are presently unknown, but their mode of growth is consistent with a bilaterian affinity.[189]

Apart from Dickinsonia, the earliest widely accepted animal fossils are the rather modern-looking cnidarians (the group that includes coral, jellyfish, sea anemones and Hydra), possibly from around 580 Ma[190] The Ediacara biota, which flourished for the last 40 million years before the start of the Cambrian,[191] were the first animals more than a very few centimetres long. Like Dickinsonia, many were flat with a "quilted" appearance, and seemed so strange that there was a proposal to classify them as a separate kingdom, Vendozoa.[192] Others, however, have been interpreted as early molluscs (Kimberella[193][194]), echinoderms (Arkarua[195]), and arthropods (Spriggina,[196] Parvancorina[197]). There is still debate about the classification of these specimens, mainly because the diagnostic features which allow taxonomists to classify more recent organisms, such as similarities to living organisms, are generally absent in the Ediacarans. However, there seems little doubt that Kimberella was at least a triploblastic bilaterian animal, in other words, an animal significantly more complex than the cnidarians.[198]

Small shelly fauna are a very mixed collection of fossils found between the Late Ediacaran and Middle Cambrian periods. The earliest, Cloudina, shows signs of successful defense against predation and may indicate the start of an evolutionary arms race. Some tiny Early Cambrian shells almost certainly belonged to molluscs, while the owners of some "armor plates," Halkieria and Microdictyon, were eventually identified when more complete specimens were found in Cambrian lagerstätten that preserved soft-bodied animals.[199]

Body plans and phyla[edit]

Kimberella, an early mollusc important for understanding the Cambrian explosion. Invertebrates are grouped into different phyla (body plans).

Invertebrates are grouped into different phyla. Informally phyla can be thought of as a way of grouping organisms according to their body plan.[200][201]:33 A body plan refers to a blueprint which describes the shape or morphology of an organism, such as its symmetry, segmentation and the disposition of its appendages. The idea of body plans originated with vertebrates, which were grouped into one phylum. But the vertebrate body plan is only one of many, and invertebrates consist of many phyla or body plans. The history of the discovery of body plans can be seen as a movement from a worldview centred on vertebrates, to seeing the vertebrates as one body plan among many. Among the pioneering zoologists, Linnaeus identified two body plans outside the vertebrates; Cuvier identified three; and Haeckel had four, as well as the Protista with eight more, for a total of twelve. For comparison, the number of phyla recognised by modern zoologists has risen to 35.[201]

Taxonomic biodiversity of accepted marine species, according to WoRMS, 18 October 2019.[202][203]
Opabinia, an extinct stem group arthropod appeared in the Middle Cambrian.[204]:124–136

Historically body plans were thought of as having evolved rapidly during the Cambrian explosion,[205] but a more nuanced understanding of animal evolution suggests a gradual development of body plans throughout the early Palaeozoic and beyond.[206] More generally a phylum can be defined in two ways: as described above, as a group of organisms with a certain degree of morphological or developmental similarity (the phenetic definition), or a group of organisms with a certain degree of evolutionary relatedness (the phylogenetic definition).[206]

In the 1970s there was already a debate about whether the emergence of the modern phyla was "explosive" or gradual but hidden by the shortage of Precambrian animal fossils.[199] A re-analysis of fossils from the Burgess Shale lagerstätte increased interest in the issue when it revealed animals, such as Opabinia, which did not fit into any known phylum. At the time these were interpreted as evidence that the modern phyla had evolved very rapidly in the Cambrian explosion and that the Burgess Shale's "weird wonders" showed that the Early Cambrian was a uniquely experimental period of animal evolution.[207] Later discoveries of similar animals and the development of new theoretical approaches led to the conclusion that many of the "weird wonders" were evolutionary "aunts" or "cousins" of modern groups[208]—for example that Opabinia was a member of the lobopods, a group which includes the ancestors of the arthropods, and that it may have been closely related to the modern tardigrades.[209] Nevertheless, there is still much debate about whether the Cambrian explosion was really explosive and, if so, how and why it happened and why it appears unique in the history of animals.[210]

Basal invertebrate animals[edit]

The most basal animal phyla, the animals that evolved first, are the Porifera, Ctenophora, Placozoa and Cnidaria. None of these basal body plans exhibit bilateral symmetry.

There has been much controversy over which invertebrate phyla, sponges or comb jellies, is the most basal.[211] Currently, sponges are more widely considered to be the most basal.[212][213]

Marine sponges[edit]

Sponges are perhaps the most basal animals. They have no nervous, digestive or circulatory system.

Sponges are animals of the phylum Porifera (from Modern Latin for bearing pores[214]). They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through them, consisting of jelly-like mesohyl sandwiched between two thin layers of cells. They have unspecialized cells that can transform into other types and that often migrate between the main cell layers and the mesohyl in the process. Sponges do not have nervous, digestive or circulatory systems. Instead, most rely on maintaining a constant water flow through their bodies to obtain food and oxygen and to remove wastes.

Sponges are similar to other animals in that they are multicellular, heterotrophic, lack cell walls and produce sperm cells. Unlike other animals, they lack true tissues and organs, and have no body symmetry. The shapes of their bodies are adapted for maximal efficiency of water flow through the central cavity, where it deposits nutrients, and leaves through a hole called the osculum. Many sponges have internal skeletons of spongin and/or spicules of calcium carbonate or silicon dioxide. All sponges are sessile aquatic animals. Although there are freshwater species, the great majority are marine (salt water) species, ranging from tidal zones to depths exceeding 8,800 m (5.5 mi). Some sponges live to great ages; there is evidence of the deep-sea glass sponge Monorhaphis chuni living about 11,000 years.[215][216]

While most of the approximately 5,000–10,000 known species feed on bacteria and other food particles in the water, some host photosynthesizing micro-organisms as endosymbionts and these alliances often produce more food and oxygen than they consume. A few species of sponge that live in food-poor environments have become carnivores that prey mainly on small crustaceans.[217]

  • Sponge biodiversity. There are four sponge species in this photo.

  • Branching vase sponge

  • Venus' flower basket at a depth of 2572 meters

  • Barrel sponge

  • The long-living Monorhaphis chuni

Linnaeus mistakenly identified sponges as plants in the order Algae.[218] For a long time thereafter sponges were assigned to a separate subkingdom, Parazoa (meaning beside the animals).[219] They are now classified as a paraphyletic phylum from which the higher animals have evolved.[220]

Ctenophores[edit]

Together with sponges, brilliantly bioluminescent ctenophores (comb jellies) are the most basal animals.

Ctenophores (from Greek for carrying a comb), commonly known as comb jellies, are a phylum that live worldwide in marine waters. They are the largest non-colonial animals to swim with the help of cilia (hairs or combs).[221] Coastal species need to be tough enough to withstand waves and swirling sediment, but some oceanic species are so fragile and transparent that it is very difficult to capture them intact for study.[222] In the past ctenophores were thought to have only a modest presence in the ocean, but it is now known they are often significant and even dominant parts of the planktonic biomass.[223]:269

The phylum has about 150 known species with a wide range of body forms. Sizes range from a few millimeters to 1.5 m (4 ft 11 in). Cydippids are egg-shaped with their cilia arranged in eight radial comb rows, and deploy retractable tentacles for capturing prey. The benthic platyctenids are generally combless and flat. The coastal beroids have gaping mouths and lack tentacles. Most adult ctenophores prey on microscopic larvae and rotifers and small crustaceans but beroids prey on other ctenophores.

  • Light diffracting along the comb rows of a cydippid, left tentacle deployed, right retracted

  • Deep-sea ctenophore trailing tentacles studded with tentilla (sub-tentacles)

  • Egg-shaped cydippid ctenophore

  • Group of small benthic creeping comb jellies streaming tentacles and living symbiotically on a starfish.

  • Lobata sp. with paired thick lobes

  • The sea walnut has a transient anus which forms only when it needs to defecate.[224]

The beroid ctenophore, mouth gaping, preys on other ctenophores.

Early writers combined ctenophores with cnidarians. Ctenophores resemble cnidarians in relying on water flow through the body cavity for both digestion and respiration, as well as in having a decentralized nerve net rather than a brain. Also like cnidarians, the bodies of ctenophores consist of a mass of jelly, with one layer of cells on the outside and another lining the internal cavity. In ctenophores, however, these layers are two cells deep, while those in cnidarians are only a single cell deep. While cnidarians exhibit radial symmetry, ctenophores have two anal canals which exhibit biradial symmetry (half-turn rotational symmetry).[225] The position of the ctenophores in the evolutionary family tree of animals has long been debated, and the majority view at present, based on molecular phylogenetics, is that cnidarians and bilaterians are more closely related to each other than either is to ctenophores.[223]:222

Placozoa[edit]

Placozoa have the simplest structure of all animals.

Placozoa (from Greek for flat animals) have the simplest structure of all animals. They are a basal form of free-living (non-parasitic) multicellular organism[226] that do not yet have a common name.[227] They form a phylum containing sofar only three described species, of which the first, the classical Trichoplax adhaerens, was discovered in 1883.[228] Two more species have been discovered since 2017,[229][230] and genetic methods indicate this phylum has a further 100 to 200 undescribed species.[231]

Food uptake by Trichoplax adhaerens

Trichoplax is a small, flattened, animal about one mm across and usually about 25 µm thick. Like the amoebae they superficially resemble, they continually change their external shape. In addition, spherical phases occasionally form which may facilitate movement. Trichoplax lacks tissues and organs. There is no manifest body symmetry, so it is not possible to distinguish anterior from posterior or left from right. It is made up of a few thousand cells of six types in three distinct layers.[232] The outer layer of simple epithelial cells bear cilia which the animal uses to help it creep along the seafloor.[233] Trichoplax feed by engulfing and absorbing food particles – mainly microbes and organic detritus – with their underside.

Marine cnidarians[edit]

Cnidarians, like this starlet sea anemone, are the simplest animals to organise cells into tissue. Yet they have the same genes that form the vertebrate (including human) head.

Cnidarians (from Greek for nettle) are distinguished by the presence of stinging cells, specialized cells that they use mainly for capturing prey. Cnidarians include corals, sea anemones, jellyfish and hydrozoans. They form a phylum containing over 10,000[234] species of animals found exclusively in aquatic (mainly marine) environments. Their bodies consist of mesoglea, a non-living jelly-like substance, sandwiched between two layers of epithelium that are mostly one cell thick. They have two basic body forms: swimming medusae and sessile polyps, both of which are radially symmetrical with mouths surrounded by tentacles that bear cnidocytes. Both forms have a single orifice and body cavity that are used for digestion and respiration.

Fossil cnidarians have been found in rocks formed about 580 million years ago. Fossils of cnidarians that do not build mineralized structures are rare. Scientists currently think cnidarians, ctenophores and bilaterians are more closely related to calcareous sponges than these are to other sponges, and that anthozoans are the evolutionary "aunts" or "sisters" of other cnidarians, and the most closely related to bilaterians.

Cnidarians are the simplest animals in which the cells are organised into tissues.[235] The starlet sea anemone is used as a model organism in research.[236] It is easy to care for in the laboratory and a protocol has been developed which can yield large numbers of embryos on a daily basis.[237] There is a remarkable degree of similarity in the gene sequence conservation and complexity between the sea anemone and vertebrates.[237] In particular, genes concerned in the formation of the head in vertebrates are also present in the anemone.[238][239]

  • Sea anemones are common in tidepools.

  • Their tentacles sting and paralyse small fish.

  • Close up of polyps on the surface of a coral, waving their tentacles.

  • If an island sinks below the sea, coral growth can keep up with rising water and form an atoll.

  • The mantle of the red paper lantern jellyfish crumples and expands like a paper lantern.[240]

  • The Portuguese man o' war is a colonial siphonophore

  • Marrus orthocanna another colonial siphonophore, assembled from two types of zooids.

  • Porpita porpita consists of a colony of hydroids[241]

  • Lion's mane jellyfish, largest known jellyfish[242]

  • Turritopsis dohrnii achieves biological immortality by transferring its cells back to childhood.[243][244]

  • The sea wasp is the most lethal jellyfish in the world.[245]

Bilateral invertebrate animals[edit]

Idealised wormlike bilaterian body plan. With a cylindrical body and a direction of movement the animal has head and tail ends. Sense organs and mouth form the basis of the head. Opposed circular and longitudinal muscles enable peristaltic motion.

Some of the earliest bilaterians were wormlike, and the original bilaterian may have been a bottom dwelling worm with a single body opening.[246] A bilaterian body can be conceptualized as a cylinder with a gut running between two openings, the mouth and the anus. Around the gut it has an internal body cavity, a coelom or pseudocoelom.[a] Animals with this bilaterally symmetric body plan have a head (anterior) end and a tail (posterior) end as well as a back (dorsal) and a belly (ventral); therefore they also have a left side and a right side.[247][248]

Having a front end means that this part of the body encounters stimuli, such as food, favouring cephalisation, the development of a head with sense organs and a mouth.[249] The body stretches back from the head, and many bilaterians have a combination of circular muscles that constrict the body, making it longer, and an opposing set of longitudinal muscles, that shorten the body;[248] these enable soft-bodied animals with a hydrostatic skeleton to move by peristalsis.[250] They also have a gut that extends through the basically cylindrical body from mouth to anus. Many bilaterian phyla have primary larvae which swim with cilia and have an apical organ containing sensory cells. However, there are exceptions to each of these characteristics; for example, adult echinoderms are radially symmetric (unlike their larvae), and certain parasitic worms have extremely simplified body structures.[247][248]

  Ikaria wariootia,
an early bilaterian[251]

Protostomes[edit]

Protostomes (from Greek for first mouth) are a superphylum of animals. It is a sister clade of the deuterostomes (from Greek for second mouth), with which it forms the Nephrozoa clade. Protostomes are distinguished from deuterostomes by the way their embryos develop. In protostomes the first opening that develops becomes the mouth, while in deuterostomes it becomes the anus.[253][254]

Marine worms[edit]

Many marine worms are related only distantly, so they form a number of different phyla. The worm shown is an arrow worm, found worldwide as a predatory component of plankton.

Worms (Old English for serpents) form a number of phyla. Different groups of marine worms are related only distantly, so they are found in several different phyla such as the Annelida (segmented worms), Chaetognatha (arrow worms), Phoronida (horseshoe worms), and Hemichordata. All worms, apart from the Hemichordata, are protostomes. The Hemichordata are deuterostomes and are discussed in their own section below.

The typical body plan of a worm involves long cylindrical tube-like bodies and no limbs. Marine worms vary in size from microscopic to over 1 metre (3.3 ft) in length for some marine polychaete worms (bristle worms)[255] and up to 58 metres (190 ft) for the marine nemertean worm (bootlace worm).[256] Some marine worms occupy a small variety of parasitic niches, living inside the bodies of other animals, while others live more freely in the marine environment or by burrowing underground. Many of these worms have specialized tentacles used for exchanging oxygen and carbon dioxide and also may be used for reproduction. Some marine worms are tube worms, such as the giant tube worm which lives in waters near underwater volcanoes and can withstand temperatures up to 90 degrees Celsius. Platyhelminthes (flatworms) form another worm phylum which includes a class of parasitic tapeworms. The marine tapeworm Polygonoporus giganticus, found in the gut of sperm whales, can grow to over 30 m (100 ft).[257][258]

Nematodes (roundworms) constitute a further worm phylum with tubular digestive systems and an opening at both ends.[259][260] Over 25,000 nematode species have been described,[261][262] of which more than half are parasitic. It has been estimated another million remain undescribed.[263] They are ubiquitous in marine, freshwater and terrestrial environments, where they often outnumber other animals in both individual and species counts. They are found in every part of the earth's lithosphere, from the top of mountains to the bottom of oceanic trenches.[264] By count they represent 90% of all animals on the ocean floor.[265] Their numerical dominance, often exceeding a million individuals per square meter and accounting for about 80% of all individual animals on earth, their diversity of life cycles, and their presence at various trophic levels point at an important role in many ecosystems.[266]

  • Giant tube worms cluster around hydrothermal vents.

  • Nematodes are ubiquitous pseudocoelomates which can parasite marine plants and animals.

  • Bloodworms are typically found on the bottom of shallow marine waters.

Marine molluscs[edit]

Bigfin reef squid displaying vivid iridescence at night. Cephalopods are the most neurologically advanced invertebrates.[267]
Blue dragon, a pelagic sea slug
Bolinus brandaris, a sea snail from which the Phoenicians extracted
royal Tyrian purple dye
      colour code: #66023C _____ [268]
Hypothetical ancestral mollusc

Molluscs (Latin for soft) form a phylum with about 85,000 extant recognized species.[269] They are the largest marine phylum in terms of species count, containing about 23% of all the named marine organisms.[270] Molluscs have more varied forms than other invertebrate phyla. They are highly diverse, not just in size and in anatomical structure, but also in behaviour and in habitat.

Drawing of a giant clam (NOAA)

The mollusc phylum is divided into 9 or 10 taxonomic classes. These classes include gastropods, bivalves and cephalopods, as well as other lesser-known but distinctive classes. Gastropods with protective shells are referred to as snails, whereas gastropods without protective shells are referred to as slugs. Gastropods are by far the most numerous molluscs in terms of species.[271] Bivalves include clams, oysters, cockles, mussels, scallops, and numerous other families. There are about 8,000 marine bivalves species (including brackish water and estuarine species). A deep sea ocean quahog clam has been reported as having lived 507 years[272] making it the longest recorded life of all animals apart from colonial animals, or near-colonial animals like sponges.[215]

  • Gastropods and bivalves
  • Marine gastropods are sea snails or sea slugs. This nudibranch is a sea slug.

  • The sea snail Syrinx aruanus has a shell up to 91 cm long, the largest of any living gastropod.

  • Molluscs usually have eyes. Bordering the edge of the mantle of a scallop, a bivalve mollusc, can be over 100 simple eyes.

  • Common mussel, another bivalve

Cephalopods include octopus, squid and cuttlefish. About 800 living species of marine cephalopods have been identified,[273] and an estimated 11,000 extinct taxa have been described.[274] They are found in all oceans, but there are no fully freshwater cephalopods.[275]

  • Cephalopods
  • The nautilus is a living fossil little changed since it evolved 500 million years ago as one of the first cephalopods.[276][277][278]

  • Reconstruction of an ammonite, a highly successful early cephalopod that appeared 400 mya.

  • Cephalopods, like this cuttlefish, use their mantle cavity for jet propulsion.

  • Colossal squid, the largest of all invertebrates[279]

Molluscs have such diverse shapes that many textbooks base their descriptions of molluscan anatomy on a generalized or hypothetical ancestral mollusc. This generalized mollusc is unsegmented and bilaterally symmetrical with an underside consisting of a single muscular foot. Beyond that it has three further key features. Firstly, it has a muscular cloak called a mantle covering its viscera and containing a significant cavity used for breathing and excretion. A shell secreted by the mantle covers the upper surface. Secondly (apart from bivalves) it has a rasping tongue called a radula used for feeding. Thirdly, it has a nervous system including a complex digestive system using microscopic, muscle-powered hairs called cilia to exude mucus. The generalized mollusc has two paired nerve cords (three in bivalves). The brain, in species that have one, encircles the esophagus. Most molluscs have eyes and all have sensors detecting chemicals, vibrations, and touch.[280][281]

Good evidence exists for the appearance of marine gastropods, cephalopods and bivalves in the Cambrian period 541 to 485.4 million years ago.

Marine arthropods[edit]

Head
___________
Thorax
___________
Abdomen
___________
Segments and tagmata of an arthropod[282] The thorax bears the main locomotory appendages. The head and thorax are fused in some arthropods, such as crabs and lobsters.
First known air-breathing animal to colonise land, the millipede Pneumodesmus newmani,[283] lived in the Early Devonian.[284]

Arthropods (Greek for jointed feet) have an exoskeleton (external skeleton), a segmented body, and jointed appendages (paired appendages). They form a phylum which includes insects, arachnids, myriapods, and crustaceans. Arthropods are characterized by their jointed limbs and cuticle made of chitin, often mineralised with calcium carbonate. The arthropod body plan consists of segments, each with a pair of appendages. The rigid cuticle inhibits growth, so arthropods replace it periodically by moulting. Their versatility has enabled them to become the most species-rich members of all ecological guilds in most environments.

The evolutionary ancestry of arthropods dates back to the Cambrian period and is generally regarded as monophyletic. However, basal relationships of arthropods with extinct phyla such as lobopodians have recently been debated.[285][286]

Some palaeontologists think Lobopodia represents a basal grade which lead to an arthropod body plan.[287]
Tardigrades (water bears) are a phylum of eight-legged, segmented microanimals able to survive in extreme conditions.
  • Arthropod fossils and living fossils
  • Fossil trilobite. Trilobites first appeared about 521 Ma. They were highly successful and were found everywhere in the ocean for 270 Ma.[288]

  • The Anomalocaris ("abnormal shrimp") was one of the first apex predators and first appeared about 515 Ma.

  • The largest known arthropod, the sea scorpion Jaekelopterus rhenaniae, has been found in estuarine strata from about 390 Ma. It was up to 2.5 m (8.2 ft) long.[289][290]

  • Horseshoe crabs are living fossils, essentially unchanged for 450 Ma.

Extant marine arthropods range in size from the microscopic crustacean Stygotantulus to the Japanese spider crab. Arthropods' primary internal cavity is a hemocoel, which accommodates their internal organs, and through which their haemolymph - analogue of blood - circulates; they have open circulatory systems. Like their exteriors, the internal organs of arthropods are generally built of repeated segments. Their nervous system is "ladder-like", with paired ventral nerve cords running through all segments and forming paired ganglia in each segment. Their heads are formed by fusion of varying numbers of segments, and their brains are formed by fusion of the ganglia of these segments and encircle the esophagus. The respiratory and excretory systems of arthropods vary, depending as much on their environment as on the subphylum to which they belong.

  • Modern crustaceans
  • Many crustaceans are very small, like this tiny amphipod, and make up a significant part of the ocean's zooplankton.

  • The Japanese spider crab has the longest leg span of any arthropod, reaching 5.5 metres (18 ft) from claw to claw.[291]

  • The Tasmanian giant crab is long-lived and slow-growing, making it vulnerable to overfishing.[292]

  • Mantis shrimp have the most advanced eyes in the animal kingdom,[293] and smash prey by swinging their club-like raptorial claws.[294]

Arthropod vision relies on various combinations of compound eyes and pigment-pit ocelli: in most species the ocelli can only detect the direction from which light is coming, and the compound eyes are the main source of information. Arthropods also have a wide range of chemical and mechanical sensors, mostly based on modifications of the many setae (bristles) that project through their cuticles. Arthropod methods of reproduction are diverse: terrestrial species use some form of internal fertilization while marine species lay eggs using either internal or external fertilization. Arthropod hatchlings vary from miniature adults to grubs that lack jointed limbs and eventually undergo a total metamorphosis to produce the adult form.

Deuterostomes[edit]

In deuterostomes the first opening that develops in the growing embryo becomes the anus, while in protostomes it becomes the mouth. Deuterostomes form a superphylum of animals and are the sister clade of the protostomes.[253][254] The earliest known deuterostomes are Saccorhytus fossils from about 540 million years ago. The Saccorhytus mouth may have functioned also as its anus.[295]

Fossil showing the mouth of the earliest known deuterostome, 540 mya

Echinoderms[edit]

Adult echinoderms have fivefold symmetry but as larvae have bilateral symmetry. This is why they are in the Bilateria.

Echinoderms (Greek for spiny skin) is a phylum which contains only marine invertebrates. The phylum contains about 7000 living species,[296] making it the second-largest grouping of deuterostomes, after the chordates.

Adult echinoderms are recognizable by their radial symmetry (usually five-point) and include starfish, sea urchins, sand dollars, and sea cucumbers, as well as the sea lilies.[297] Echinoderms are found at every ocean depth, from the intertidal zone to the abyssal zone. They are unique among animals in having bilateral symmetry at the larval stage, but fivefold symmetry (pentamerism, a special type of radial symmetry) as adults.[298]

Echinoderms are important both biologically and geologically. Biologically, there are few other groupings so abundant in the biotic desert of the deep sea, as well as shallower oceans. Most echinoderms are able to regenerate tissue, organs, limbs, and reproduce asexually; in some cases, they can undergo complete regeneration from a single limb. Geologically, the value of echinoderms is in their ossified skeletons, which are major contributors to many limestone formations, and can provide valuable clues as to the geological environment. They were the most used species in regenerative research in the 19th and 20th centuries.

  • Echinoderm literally means "spiny skin", as this water melon sea urchin illustrates.

  • The ochre sea star was the first keystone predator to be studied. They limit mussels which can overwhelm intertidal communities.[299]

  • Colorful sea lilies in shallow waters

  • Sea cucumbers filter feed on plankton and suspended solids.

  • The sea pig, a deep water sea cucumber, is the only echinoderm that uses legged locomotion.

  • A benthopelagic and bioluminescence swimming sea cucumber, 3200 metres deep

It is held by some scientists that the radiation of echinoderms was responsible for the Mesozoic Marine Revolution. Aside from the hard-to-classify Arkarua (a Precambrian animal with echinoderm-like pentamerous radial symmetry), the first definitive members of the phylum appeared near the start of the Cambrian.

Hemichordates[edit]

Gill (pharyngeal) slits
The acorn worm is associated with the development of gill slits.
Gill slits in an acorn worm (left) and tunicate (right)
Gill slits have been described as "the foremost morphological innovation of early deuterostomes".[300][301] In aquatic organisms, gill slits allow water that enters the mouth during feeding to exit. Some invertebrate chordates also use the slits to filter food from the water.[302]

Hemichordates form a sister phylum to the echinoderms. They are solitary worm-shaped organisms rarely seen by humans because of their lifestyle. They include two main groups, the acorn worms and the Pterobranchia. Pterobranchia form a class containing about 30 species of small worm-shaped animals that live in secreted tubes on the ocean floor. Acorn worms form a class containing about 111 species that generally live in U-shaped burrows on the seabed, from the shoreline to a depth of 3000 metres. The worms lie there with the proboscis sticking out of one opening in the burrow, subsisting as deposit feeders or suspension feeders. It is supposed the ancestors of acorn worms used to live in tubes like their relatives, the Pterobranchia, but eventually started to live a safer and more sheltered existence in sediment burrows.[303] Some of these worms may grow to be very long; one particular species may reach a length of 2.5 metres (8 ft 2 in), although most acorn worms are much smaller.

Acorn worms are more highly specialised and advanced than other worm-like organisms. They have a circulatory system with a heart that also functions as a kidney. Acorn worms have gill-like structures they use for breathing, similar to the gills of fish. Therefore, acorn worms are sometimes said to be a link between classical invertebrates and vertebrates. Acorn worms continually form new gill slits as they grow in size, and some older individuals have more than a hundred on each side. Each slit consists of a branchial chamber opening to the pharynx through a U-shaped cleft. Cilia push water through the slits, maintaining a constant flow, just as in fish.[304] Some acorn worms also have a postanal tail which may be homologous to the post-anal tail of vertebrates.

The three-section body plan of the acorn worm is no longer present in the vertebrates, except in the anatomy of the frontal neural tube, later developed into a brain divided into three parts. This means some of the original anatomy of the early chordate ancestors is still present in vertebrates even if it is not always visible. One theory is the three-part body originated from an early common ancestor of the deuterostomes, and maybe even from a common bilateral ancestor of both deuterostomes and protostomes. Studies have shown the gene expression in the embryo share three of the same signaling centers that shape the brains of all vertebrates, but instead of taking part in the formation of their neural system,[305] they are controlling the development of the different body regions.[306]

Marine chordates[edit]

The lancelet, like all cephalochordates, has a head. Adult lancelets retain the four key features of chordates: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail. Water from the mouth enters the pharyngeal slits, which filter out food particles. The filtered water then collects in the atrium and exits through the atriopore.[307]

The chordate phylum has three subphyla, one of which is the vertebrates (see below). The other two subphyla are marine invertebrates: the tunicates (salps and sea squirts) and the cephalochordates (such as lancelets). Invertebrate chordates are close relatives to vertebrates. In particular, there has been discussion about how closely some extinct marine species, such as Pikaiidae, Palaeospondylus, Zhongxiniscus and Vetulicolia, might relate ancestrally to vertebrates.

  • Invertebrate chordates are close relatives of vertebrates
  • The lancelet, a small translucent fish-like cephalochordate, is the closest living invertebrate relative of the vertebrates.[308][309]

  • Tunicates, like these fluorescent-colored sea squirts, may provide clues to vertebrate and therefore human ancestry.[310]

  • Pyrosomes are free-floating bioluminescent tunicates made up of hundreds of individuals.

  • Salp chain

In chordates, the four above labelled common features appear at some point during development.[302]
The larval stage of the tunicate possesses all of the features characteristic of chordates: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail.[302]
In the adult stage of the tunicate the notochord, nerve cord, and tail disappear.[302]

Vertebrate animals[edit]

Ray-finned fish
Marine tetrapod (sperm whale)
Skeletal structures showing the vertebral column and internal skeleton running from the head to the tail.

Vertebrates (Latin for joints of the spine) are a subphylum of chordates. They are chordates that have a vertebral column (backbone). The vertebral column provides the central support structure for an internal skeleton which gives shape, support, and protection to the body and can provide a means of anchoring fins or limbs to the body. The vertebral column also serves to house and protect the spinal cord that lies within the vertebral column.

Marine vertebrates can be divided into marine fish and marine tetrapods.

Marine fish[edit]

Fish typically breathe by extracting oxygen from water through gills and have a skin protected by scales and mucous. They use fins to propel and stabilise themselves in the water, and usually have a two-chambered heart and eyes well adapted to seeing underwater, as well as other sensory systems. Over 33,000 species of fish have been described as of 2017,[311] of which about 20,000 are marine fish.[312]

Jawless fish[edit]

The Tully monster, a strange looking extinct animal with eyes like a hammerhead protruding from its back, may be an early jawless fish.

Early fish had no jaws. Most went extinct when they were outcompeted by jawed fish (below), but two groups survived: hagfish and lampreys. Hagfish form a class of about 20 species of eel-shaped, slime-producing marine fish. They are the only known living animals that have a skull but no vertebral column. Lampreys form a superclass containing 38 known extant species of jawless fish.[313] The adult lamprey is characterized by a toothed, funnel-like sucking mouth. Although they are well known for boring into the flesh of other fish to suck their blood,[314] only 18 species of lampreys are actually parasitic.[315] Together hagfish and lampreys are the sister group to vertebrates. Living hagfish remain similar to hagfish from around 300 million years ago.[316] The lampreys are a very ancient lineage of vertebrates, though their exact relationship to hagfishes and jawed vertebrates is still a matter of dispute.[317] Molecular analysis since 1992 has suggested that hagfish are most closely related to lampreys,[318] and so also are vertebrates in a monophyletic sense. Others consider them a sister group of vertebrates in the common taxon of craniata.[319]

The Tully monster is an extinct genus of soft-bodied bilaterians that lived in tropical estuaries about 300 million years ago. Since 2016 there has been controversy over whether this animal was a vertebrate or an invertebrate.[320][321] In 2020 researchers found "strong evidence" that the Tully monster was a vertebrate, and was a jawless fish in the lineage of the lamprey.[322][323]

  • Hagfish are the only known living animals with a skull but no vertebral column.

  • Lampreys are often parasitic and have a toothed, funnel-like sucking mouth.

  • The extinct Pteraspidomorphi, ancestral to jawed vertebrates

Pteraspidomorphi is an extinct class of early jawless fish ancestral to jawed vertebrates. The few characteristics they share with the latter are now considered as primitive for all vertebrates.

Around the start of the Devonian, fish started appearing with a deep remodelling of the vertebrate skull that resulted in a jaw.[324]All vertebrate jaws, including the human jaw, have evolved from these early fish jaws. The appearance of the early vertebrate jaw has been described as "perhaps the most profound and radical evolutionary step in vertebrate history".[325][326] Jaws make it possible to capture, hold, and chew prey. Fish without jaws had more difficulty surviving than fish with jaws, and most jawless fish became extinct during the Triassic period.

Cartilaginous fish[edit]

Jawed fish fall into two main groups: fish with bony internal skeletons and fish with cartilaginous internal skeletons. Cartilaginous fish, such as sharks and rays, have jaws and skeletons made of cartilage rather than bone. Megalodon is an extinct species of shark that lived about 28 to 1.5 Ma. It looked much like a stocky version of the great white shark, but was much larger with fossil lengths reaching 20.3 metres (67 ft).[327] Found in all oceans[328] it was one of the largest and most powerful predators in vertebrate history,[327] and probably had a profound impact on marine life.[329] The Greenland shark has the longest known lifespan of all vertebrates, about 400 years.[330] Some sharks such as the great white are partially warm blooded and give live birth. The manta ray, largest ray in the world, has been targeted by fisheries and is now vulnerable.[331]

  • Cartilaginous fishes
  • Cartilaginous fishes may have evolved from spiny sharks.

  • Stingray

  • Manta ray, the largest ray

  • Sawfish, rays with long rostrums resembling a saw. All species are now endangered.[332]

  • The extinct megalodon resembled a giant great white shark.

  • The Greenland shark lives longer than any other vertebrate.

  • The largest extant fish, the whale shark, is now a vulnerable species.

Bony fish[edit]

Guiyu oneiros, the earliest-known bony fish lived during the Late Silurian 419 million years ago.
Lobe fins are bedded into the body by bony stalks. They evolved into the legs of the first tetrapod land vertebrates.
Ray fins have spines (rays) which can be erected to stiffen the fin for better control of swimming performance.

Bony fish have jaws and skeletons made of bone rather than cartilage. Bony fish also have hard, bony plates called operculum which help them respire and protect their gills, and they often possess a swim bladder which they use for better control of their buoyancy. Bony fish can be further divided into those with lobe fins and those with ray fins. The approximate dates in the phylogenetic tree are from Near et al., 2012[333] and Zhu et al., 2009.[334]

Lobe fins have the form of fleshy lobes supported by bony stalks which extend from the body.[335] Guiyu oneiros, the earliest-known bony fish, lived during the Late Silurian 419 million years ago. It has the combination of both ray-finned and lobe-finned features, although analysis of the totality of its features place it closer to lobe-finned fish.[334] Lobe fins evolved into the legs of the first tetrapod land vertebrates, so by extension an early ancestor of humans was a lobe-finned fish. Apart from the coelacanths and the lungfishes, lobe-finned fishes are now extinct.

The remaining bony fish have ray fins. These are made of webs of skin supported by bony or horny spines (rays) which can be erected to control the fin stiffness.

  • The main distinguishing feature of the chondrosteans (sturgeon, paddlefish, bichir and reedfish) is the cartilaginous nature of their skeletons. The ancestors of the chondrosteans are thought to be bony fish, but the characteristic of an ossified skeleton was lost in later evolutionary development, resulting in a lightening of the frame.[336]
  • Neopterygians (from Greek for new fins) appeared sometime in the Late Permian, before dinosaurs. They were a very successful group of fish, because they could move more rapidly than their ancestors. Their scales and skeletons began to lighten during their evolution, and their jaws became more powerful and efficient.[337]

Teleosts[edit]

Teleosts have homocercal tails.

About 96% of all modern fish species are teleosts,[338] of which about 14,000 are marine species.[339] Teleosts can be distinguished from other bony fish by their possession of a homocercal tail, a tail where the upper half mirrors the lower half.[340] Another difference lies in their jaw bones – teleosts have modifications in the jaw musculature which make it possible for them to protrude their jaws. This enables them to grab prey and draw it into their mouth.[340] In general, teleosts tend to be quicker and more flexible than more basal bony fishes. Their skeletal structure has evolved towards greater lightness. While teleost bones are well calcified, they are constructed from a scaffolding of struts, rather than the dense cancellous bones of holostean fish.[341]

Teleosts are found in almost all marine habitats.[342] They have enormous diversity, and range in size from adult gobies 8mm long [343] to ocean sunfish weighting over 2,000 kg.[344] The following images show something of the diversity in the shape and colour of modern marine teleosts...

  • Sailfish

  • Mahi-mahi

  • Eel

  • Sea-horse

  • Ocean sunfish

  • Anglerfish

  • Pufferfish

  • Clown triggerfish

  • Mandarin dragonet

Nearly half of all extant vertebrate species are teleosts.[345]

Marine tetrapods[edit]

Tiktaalik, an extinct lobe-finned fish, developed limb-like fins that could take it onto land.

A tetrapod (Greek for four feet) is a vertebrate with limbs (feet). Tetrapods evolved from ancient lobe-finned fishes about 400 million years ago during the Devonian Period when their earliest ancestors emerged from the sea and adapted to living on land.[346] This change from a body plan for breathing and navigating in gravity-neutral water to a body plan with mechanisms enabling the animal to breath in air without dehydrating and move on land is one of the most profound evolutionary changes known.[347][348] Tetrapods can be divided into four classes: amphibians, reptiles, birds and mammals.

Marine tetrapods are tetrapods that returned from land back to the sea again. The first returns to the ocean may have occurred as early as the Carboniferous Period[349] whereas other returns occurred as recently as the Cenozoic, as in cetaceans, pinnipeds,[350] and several modern amphibians.[351] Amphibians (from Greek for both kinds of life) live part of their life in water and part on land. They mostly require fresh water to reproduce. A few inhabit brackish water, but there are no true marine amphibians.[352] There have been reports, however, of amphibians invading marine waters, such as a Black Sea invasion by the natural hybrid Pelophylax esculentus reported in 2010.[353]

Reptiles[edit]

Reptiles (Late Latin for creeping or crawling) do not have an aquatic larval stage, and in this way are unlike amphibians. Most reptiles are oviparous, although several species of squamates are viviparous, as were some extinct aquatic clades[354] — the fetus develops within the mother, contained in a placenta rather than an eggshell. As amniotes, reptile eggs are surrounded by membranes for protection and transport, which adapt them to reproduction on dry land. Many of the viviparous species feed their fetuses through various forms of placenta analogous to those of mammals, with some providing initial care for their hatchlings.

Some reptiles are more closely related to birds than other reptiles, and many scientists prefer to make Reptilia a monophyletic group which includes the birds.[355][356][357][358] Extant non-avian reptiles which inhabit or frequent the sea include sea turtles, sea snakes, terrapins, the marine iguana, and the saltwater crocodile. Currently, of the approximately 12,000 extant reptile species and sub-species, only about 100 of are classed as marine reptiles.[359]

Except for some sea snakes, most extant marine reptiles are oviparous and need to return to land to lay their eggs. Apart from sea turtles, the species usually spend most of their lives on or near land rather than in the ocean. Sea snakes generally prefer shallow waters nearby land, around islands, especially waters that are somewhat sheltered, as well as near estuaries.[360][361] Unlike land snakes, sea snakes have evolved flattened tails which help them swim.[362]

  • Marine iguana

  • Leatherback sea turtle

  • Saltwater crocodile

  • Marine snakes have flattened tails.

  • The ancient Ichthyosaurus communis independently evolved flippers similar to dolphins.

Some extinct marine reptiles, such as ichthyosaurs, evolved to be viviparous and had no requirement to return to land. Ichthyosaurs resembled dolphins. They first appeared about 245 million years ago and disappeared about 90 million years ago. The terrestrial ancestor of the ichthyosaur had no features already on its back or tail that might have helped along the evolutionary process. Yet the ichthyosaur developed a dorsal and tail fin which improved its ability to swim.[363] The biologist Stephen Jay Gould said the ichthyosaur was his favourite example of convergent evolution.[364] The earliest marine reptiles arose in the Permian. During the Mesozoic many groups of reptiles became adapted to life in the seas, including ichthyosaurs, plesiosaurs, mosasaurs, nothosaurs, placodonts, sea turtles, thalattosaurs and thalattosuchians. Marine reptiles were less numerous after mass extinction at the end of the Cretaceous.

Birds[edit]

Waterbird food web in Chesapeake Bay

Marine birds are adapted to life within the marine environment. They are often called seabirds. While marine birds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations. Examples include albatross, penguins, gannets, and auks.

In general, marine birds live longer, breed later and have fewer young than terrestrial birds do, but they invest a great deal of time in their young. Most species nest in colonies, which can vary in size from a few dozen birds to millions. Many species are famous for undertaking long annual migrations, crossing the equator or circumnavigating the Earth in some cases. They feed both at the ocean's surface and below it, and even feed on each other. Marine birds can be highly pelagic, coastal, or in some cases spend a part of the year away from the sea entirely. Some marine birds plummet from heights, plunging through the water leaving vapour-like trails, similar to that of fighter planes.[365] Gannets plunge into the water at up to 100 kilometres per hour (60 mph). They have air sacs under their skin in their face and chest which act like bubble-wrap, cushioning the impact with the water.

  • European herring gull attack herring schools from above.

  • Gentoo penguin swimming underwater

  • Gannets "divebomb" at high speed.

  • Albatrosses range over huge areas of ocean and regularly circle the globe.

The first marine birds evolved in the Cretaceous period, and modern marine bird families emerged in the Paleogene.

Mammals[edit]

Sea otter, a classic keystone species which controls sea urchin numbers

Mammals (from Latin for breast) are characterised by the presence of mammary glands which in females produce milk for feeding (nursing) their young. There are about 130 living and recently extinct marine mammal species such as seals, dolphins, whales, manatees, sea otters and polar bears.[366] They do not represent a distinct taxon or systematic grouping, but are instead unified by their reliance on the marine environment for feeding. Both cetaceans and sirenians are fully aquatic and therefore are obligate water dwellers. Seals and sea-lions are semiaquatic; they spend the majority of their time in the water, but need to return to land for important activities such as mating, breeding and molting. In contrast, both otters and the polar bear are much less adapted to aquatic living. Their diet varies considerably as well: some may eat zooplankton; others may eat fish, squid, shellfish, and sea-grass; and a few may eat other mammals.

In a process of convergent evolution, marine mammals, especially cetaceans such as dolphins and whales, redeveloped their body plan to parallel the streamlined fusiform body plan of pelagic fish. Front legs became flippers and back legs disappeared, a dorsal fin reappeared and the tail morphed into a powerful horizontal fluke. This body plan is an adaptation to being an active predator in a high drag environment. A parallel convergence occurred with the now extinct marine reptile ichthyosaur.[367]

  • Endangered blue whale, the largest living animal[368]

  • Bottlenose dolphin, which has the highest encephalization of any animal after humans[369]

  • Beluga whale

  • Dugong grazing on seagrass

  • Walrus

  • Polar bear

Primary producers[edit]

Composite image showing the global distribution of photosynthesis, including both oceanic phytoplankton and terrestrial vegetation. Dark red and blue-green indicate regions of high photosynthetic activity in the ocean and on land, respectively.

Primary producers are the autotroph organisms that make their own food instead of eating other organisms. This means primary producers become the starting point in the food chain for heterotroph organisms that do eat other organisms. Some marine primary producers are specialised bacteria and archaea which are chemotrophs, making their own food by gathering around hydrothermal vents and cold seeps and using chemosynthesis. However most marine primary production comes from organisms which use photosynthesis on the carbon dioxide dissolved in the water. This process uses energy from sunlight to convert water and carbon dioxide[370]:186–187 into sugars that can be used both as a source of chemical energy and of organic molecules that are used in the structural components of cells.[370]:1242 Marine primary producers are important because they underpin almost all marine animal life by generating most of the oxygen and food that provide other organisms with the chemical energy they need to exist.

The principal marine primary producers are cyanobacteria, algae and marine plants. The oxygen released as a by-product of photosynthesis is needed by nearly all living things to carry out cellular respiration. In addition, primary producers are influential in the global carbon and water cycles. They stabilize coastal areas and can provide habitats for marine animals. The term division has been traditionally used instead of phylum when discussing primary producers, but the International Code of Nomenclature for algae, fungi, and plants now accepts both terms as equivalents.[371]

Cyanobacteria[edit]

Cyanobacteria
Cyanobacteria from a microbial mat. Cyanobacteria were the first organisms to release oxygen via photosynthesis.
The cyanobacterium genus Prochlorococcus is a major contributor to atmospheric oxygen.

Cyanobacteria were the first organisms to evolve an ability to turn sunlight into chemical energy. They form a phylum (division) of bacteria which range from unicellular to filamentous and include colonial species. They are found almost everywhere on earth: in damp soil, in both freshwater and marine environments, and even on Antarctic rocks.[372] In particular, some species occur as drifting cells floating in the ocean, and as such were amongst the first of the phytoplankton.

The first primary producers that used photosynthesis were oceanic cyanobacteria about 2.3 billion years ago.[373][374] The release of molecular oxygen by cyanobacteria as a by-product of photosynthesis induced global changes in the Earth's environment. Because oxygen was toxic to most life on Earth at the time, this led to the near-extinction of oxygen-intolerant organisms, a dramatic change which redirected the evolution of the major animal and plant species.[375]

The tiny marine cyanobacterium Prochlorococcus, discovered in 1986, forms today part of the base of the ocean food chain and accounts for much of the photosynthesis of the open ocean[376] and an estimated 20% of the oxygen in the Earth's atmosphere.[377] It is possibly the most plentiful genus on Earth: a single millilitre of surface seawater may contain 100,000 cells or more.[378]

Originally, biologists classified cyanobacteria as algae, and referred to it as "blue-green algae". The more recent view is that cyanobacteria is a bacteria, and hence is not even in the same Kingdom as algae. Most authorities today exclude all prokaryotes, and hence cyanobacteria from the definition of algae.[379][380]

Algae[edit]

Diatoms
          Centric
        Pennate
Diatoms have a silica shell (frustule) with radial (centric) or bilateral (pennate) symmetry.
Dinoflagellates
        Armoured
        Unarmoured
Traditionally dinoflagellates have been presented as armoured or unarmoured.

Algae is an informal term for a widespread and diverse group of photosynthetic protists which are not necessarily closely related and are thus polyphyletic. Marine algae can be divided into six groups:

  • green algae, an informal group containing about 8,000 recognised species.[381] Many species live most of their lives as single cells or are filamentous, while others form colonies made up from long chains of cells, or are highly differentiated macroscopic seaweeds.
  • red algae, a (disputed) phylum containing about 7,000 recognised species,[382] mostly multicellular and including many notable seaweeds.[382][383]
  • brown algae, a class containing about 2,000 recognised species,[384] mostly multicellular and including many seaweeds, including kelp
  • diatoms, a (disputed) phylum containing about 100,000 recognised species of mainly unicellular algae. Diatoms generate about 20 percent of the oxygen produced on the planet each year,[151] take in over 6.7 billion metric tons of silicon each year from the waters in which they live,[385] and contribute nearly half of the organic material found in the oceans. The shells (frustules) of dead diatoms can reach as much as half a mile deep on the ocean floor.[386]
  • dinoflagellates, a phylum of unicellular flagellates with about 2,000 marine species.[387] Many dinoflagellates are known to be photosynthetic, but a large fraction of these are in fact mixotrophic, combining photosynthesis with ingestion of prey (phagotrophy).[388] Some species are endosymbionts of marine animals and play an important part in the biology of coral reefs. Others predate other protozoa, and a few forms are parasitic.
  • euglenophytes, a phylum of unicellular flagellates with only a few marine members

Unlike higher plants, algae lack roots, stems, or leaves. They can be classified by size as microalgae or macroalgae.

Microalgae are the microscopic types of algae, not visible to the naked eye. They are mostly unicellular species which exist as individuals or in chains or groups, though some are multicellular. Microalgae are important components of the marine protists (discussed above), as well as the phytoplankton (discussed below). They are very diverse. It has been estimated there are 200,000-800,000 species of which about 50,000 species have been described.[389] Depending on the species, their sizes range from a few micrometers (µm) to a few hundred micrometers. They are specially adapted to an environment dominated by viscous forces.

  • Chlamydomonas globosa, a unicellular green alga with two flagella just visible at bottom left

  • Chlorella vulgaris, a common green microalgae, in endosymbiosis with a ciliate[390]

  • Centric diatom

  • Dinoflagellates

Macroalgae are the larger, multicellular and more visible types of algae, commonly called seaweeds. Seaweeds usually grow in shallow coastal waters where they are anchored to the seafloor by a holdfast. Seaweed that becomes adrift can wash up on beaches. Kelp is a large brown seaweed that forms large underwater forests covering about 25% of the world coastlines.[391] They are among the most productive and dynamic ecosystems on Earth.[392] Some Sargassum seaweeds are planktonic (free-floating). Like microalgae, macroalgae (seaweeds) are technically marine protists since they are not true plants.

  • A seaweed is a macroscopic form of
    red or brown or green algae.

  • Sargassum seaweed is a planktonic brown alga with air bladders that help it float.

  • Sargassum fish are camouflaged to live among drifting Sargassum seaweed.

Kelp forests are among the most productive ecosystems on the planet.

  • Unicellular macroalgae (see also macroscopic protists ←)
  • The unicellular bubble algae lives in tidal zones. It can have a 4 cm diameter.[393]

  • The unicellular mermaid's wineglass are mushroom-shaped algae that grow up to 10 cm high.

  • Killer algae are single-celled organisms, but look like ferns and grow stalks up to 80 cm long.[394]

Unicellular organisms are usually microscopic, less than one tenth of a millimeter long. There are exceptions. Mermaid's wineglass, a genus of subtropical green algae, is single-celled but remarkably large and complex in form with a single large nucleus, making it a model organism for studying cell biology.[395] Another single celled algae, Caulerpa taxifolia, has the appearance of a vascular plant including "leaves" arranged neatly up stalks like a fern. Selective breeding in aquariums to produce hardier strains resulted in an accidental release into the Mediterranean where it has become an invasive species known colloquially as killer algae.[396]

Origin of plants[edit]

Evolution of mangroves and seagrasses

Back in the Silurian, some phytoplankton evolved into red, brown and green algae. These algae then invaded the land and started evolving into the land plants we know today. Later, in the Cretaceous, some of these land plants returned to the sea as marine plants, such as mangroves and seagrasses.[397]

Marine plants can be found in intertidal zones and shallow waters, such as seagrasses like eelgrass and turtle grass, Thalassia. These plants have adapted to the high salinity of the ocean environment. Plant life can also flourish in the brackish waters of estuaries, where mangroves or cordgrass or beach grass beach grass might grow.

  • Mangroves

  • Seagrass meadow

  • Sea dragons camouflaged to look like floating seaweed live in kelp forests and seagrass meadows.[398]

The total world area of mangrove forests was estimated in 2010 as 134,257 square kilometres (51,837 sq mi) (based on satellite data).[399][400] The total world area of seagrass meadows is more difficult to determine, but was conservatively estimated in 2003 as 177,000 square kilometres (68,000 sq mi).[401]

Mangroves and seagrasses provide important nursery habitats for marine life, acting as hiding and foraging places for larval and juvenile forms of larger fish and invertebrates.

  • Spalding, M. (2010) World atlas of mangroves, Routledge. ISBN 9781849776608. doi:10.4324/9781849776608.

Plankton and trophic interactions[edit]

Plankton are drifting or floating organisms that cannot swim against a current, and include organisms from most areas of life: bacteria, archaea, algae, protozoa and animals.

Plankton (from Greek for wanderers) are a diverse group of organisms that live in the water column of large bodies of water but cannot swim against a current. As a result, they wander or drift with the currents.[402] Plankton are defined by their ecological niche, not by any phylogenetic or taxonomic classification. They are a crucial source of food for many marine animals, from forage fish to whales. Plankton can be divided into a plant-like component and an animal component.

Phytoplankton[edit]

Phytoplankton are the plant-like components of the plankton community ("phyto" comes from the Greek for plant). They are autotrophic (self-feeding), meaning they generate their own food and do not need to consume other organisms.

Phytoplankton consist mainly of microscopic photosynthetic eukaryotes which inhabit the upper sunlit layer in all oceans. They need sunlight so they can photosynthesize. Most phytoplankton are single-celled algae, but other phytoplankton are bacteria and some are protists.[403] Phytoplankton groups include cyanobacteria (above), diatoms, various other types of algae (red, green, brown, and yellow-green), dinoflagellates, euglenoids, coccolithophorids, cryptomonads, chrysophytes, chlorophytes, prasinophytes, and silicoflagellates. They form the base of the primary production that drives the ocean food web, and account for half of the current global primary production, more than the terrestrial forests.[404]

Coccolithophores
...have plates called coccoliths
...extinct fossil
Coccolithophores build calcite skeletons important to the marine carbon cycle.[405]
  • Phytoplankton
  • Phytoplankton are the foundation of the ocean food chain.

  • Phytoplankton come in many shapes and sizes.

  • Diatoms are one of the most common types of phytoplankton.

  • Colonial phytoplankton

  • The cyanobacterium Prochlorococcus accounts for much of the ocean's primary production.

  • Green cyanobacteria scum washed up on a rock in California

  • Gyrodinium, one of the few naked dinoflagellates which lack armour

  • Zoochlorellae (green) living inside the ciliate Stichotricha secunda

There are over 100,000 species of diatoms which account for 50% of the ocean's primary production.
Play media
Red, orange, yellow and green represent areas where algal blooms abound. Blue areas represent nutrient-poor zones where phytoplankton exist in lower concentrations.
  • Coccolithophores named after the BBC documentary series
    The Blue Planet
  • The coccolithophore Emiliania huxleyi

  • Algae bloom of Emiliania huxleyi off the southern coast of England

  • Guinardia delicatula, a diatom responsible for algal blooms in the North Sea and the English Channel[406]

Zooplankton[edit]

Radiolarians
          Drawings by Haeckel 1904 (click for details)

Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek for animal). They are heterotrophic (other-feeding), meaning they cannot produce their own food and must consume instead other plants or animals as food. In particular, this means they eat phytoplankton.

Foraminiferans
...can have more than one nucleus
...and defensive spines
Foraminiferans are important unicellular zooplankton protists, with calcium shells.
Turing and radiolarian morphology
Shell of a spherical radiolarian
Shell micrographs
Computer simulations of Turing patterns on a sphere
closely replicate some radiolarian shell patterns.[407]

Zooplankton are generally larger than phytoplankton, mostly still microscopic but some can be seen with the naked eye. Many protozoans (single-celled protists that prey on other microscopic life) are zooplankton, including zooflagellates, foraminiferans, radiolarians and some dinoflagellates. Other dinoflagellates are mixotrophic and could also be classified as phytoplankton; the distinction between plants and animals often breaks down in very small organisms. Other zooplankton include pelagic cnidarians, ctenophores, molluscs, arthropods and tunicates, as well as planktonic arrow worms and bristle worms.

Radiolarians are unicellular protists with elaborate silica shells

Microzooplankton: major grazers of the plankton

  • Radiolarians come in many shapes.

  • Group of planktic foraminiferans

  • Copepods eat phytoplankton. This one is carrying eggs.

  • The dinoflagellate, Protoperidinium extrudes a large feeding veil to capture prey.

Larger zooplankton can be predatory on smaller zooplankton.

Macrozooplankton


  • Moon jellyfish

  • Venus girdle, a ctenophore

  • Arrow worm

  • Tomopteris, a planktonic segmented worm with unusual yellow bioluminescence[408]

  • Marine amphipod

  • Krill

  • Pelagic sea cucumber

Many marine animals begin life as zooplankton in the form of eggs or larvae, before they develop into adults. These are meroplanktic, that is, they are planktonic for only part of their life.

  • Larvae and juveniles
  • Salmon larva hatching from its egg

  • Ocean sunfish larva

  • Juvenile planktonic squid

  • Larva stage of a spiny lobster

Mixotrophic plankton[edit]

A surf wave at night sparkles with blue light due to the presence of a bioluminescent dinoflagellate, such as Lingulodinium polyedrum
A suggested explanation for glowing seas[409]

Dinoflagellates are often mixotrophic or live in symbiosis with other organisms.

  • Mixoplankton
  • Tintinnid ciliate Favella

  • Euglena mutabilis, a photosynthetic flagellate

  • Noctiluca scintillans, a bioluminescence dinoflagellate

Some dinoflagellates are bioluminescent. At night, ocean water can light up internally and sparkle with blue light because of these dinoflagellates.[410][411] Bioluminescent dinoflagellates possess scintillons, individual cytoplasmic bodies which contain dinoflagellate luciferase, the main enzyme involved in the luminescence. The luminescence, sometimes called the phosphorescence of the sea, occurs as brief (0.1 sec) blue flashes or sparks when individual scintillons are stimulated, usually by mechanical disturbances from, for example, a boat or a swimmer or surf.[412]

Marine food web[edit]

Pelagic food web

Compared to terrestrial environments, marine environments have biomass pyramids which are inverted at the base. In particular, the biomass of consumers (copepods, krill, shrimp, forage fish) is larger than the biomass of primary producers. This happens because the ocean's primary producers are tiny phytoplankton which tend to be r-strategists that grow and reproduce rapidly, so a small mass can have a fast rate of primary production. In contrast, terrestrial primary producers, such as mature forests, are often K-strategists that grow and reproduce slowly, so a much larger mass is needed to achieve the same rate of primary production.

Because of this inversion, it is the zooplankton that make up most of the marine animal biomass. As primary consumers, they are the crucial link between the primary producers (mainly phytoplankton) and the rest of the marine food web (secondary consumers).[413]

If phytoplankton dies before it is eaten, it descends through the euphotic zone as part of the marine snow and settles into the depths of sea. In this way, phytoplankton sequester about 2 billion tons of carbon dioxide into the ocean each year, causing the ocean to become a sink of carbon dioxide holding about 90% of all sequestered carbon.[414]

In 2010 researchers found whales carry nutrients from the depths of the ocean back to the surface using a process they called the whale pump.[415] Whales feed at deeper levels in the ocean where krill is found, but return regularly to the surface to breathe. There whales defecate a liquid rich in nitrogen and iron. Instead of sinking, the liquid stays at the surface where phytoplankton consume it. In the Gulf of Maine the whale pump provides more nitrogen than the rivers.[416]

Sediments and biogenic ooze[edit]

Thickness of marine sediments

Sediments at the bottom of the ocean have two main origins, terrigenous and biogenous. Terrigenous sediments account for about 45% of the total marine sediment, and originate in the erosion of rocks on land, transported by rivers and land runoff, windborne dust, volcanoes, or grinding by glaciers.

Biogenous sediments account for the other 55% of the total sediment, and originate in the skeletal remains of marine protists (single-celled plankton and benthos organisms). Much smaller amounts of precipitated minerals and meteoric dust can also be present. Ooze, in the context of a marine sediment, does not refer to the consistency of the sediment but to its biological origin. The term ooze was originally used by John Murray, the "father of modern oceanography", who proposed the term radiolarian ooze for the silica deposits of radiolarian shells brought to the surface during the Challenger Expedition.[417] A biogenic ooze is a pelagic sediment containing at least 30 percent from the skeletal remains of marine organisms.

  • An elaborate mineral skeleton of a radiolarian made of silica.

  • Diatoms, major components of marine plankton, also have silica skeletons called frustules.

  • Coccolithophores have plates or scales made with calcium carbonate called coccoliths

  • Calcified test of a planktic foraminiferan

  • A diatom microfossil from 40 million years ago

  • Diatomaceous earth is a soft, siliceous, sedimentary rock made up of microfossils in the form of the frustules (shells) of single cell diatoms (click to magnify).

  • Illustration of a Globigerina ooze

  • Shells (tests), usually made of calcium carbonate, from a foraminiferal ooze on the deep ocean floor

Biogeochemical cycles[edit]

Marine biogeochemical cycles
The dominant feature of the planet viewed from space is water – oceans of liquid water flood most of the surface while water vapour swirls in atmospheric clouds and the poles are capped with ice.

Taken as a whole, the oceans form a single marine system where water – the "universal solvent" [422] – dissolves nutrients and substances containing elements such as oxygen, carbon, nitrogen and phosphorus. These substances are endlessly cycled and recycled, chemically combined and then broken down again, dissolved and then precipitated or evaporated, imported from and exported back to the land and the atmosphere and the ocean floor. Powered both by the biological activity of marine organisms and by the natural actions of the sun and tides and movements within the Earth's crust, these are the marine biogeochemical cycles.[423][424]

  • Marine carbon cycle[425]

  • Oxygen cycle

  • Marine nitrogen cycle
  • Marine phosphorus cycle

Land interactions[edit]

The drainage basins of the principal oceans and seas of the world are marked by continental divides. The grey areas are endorheic basins that do not drain to the ocean.

Land interactions impact marine life in many ways. Coastlines typically have continental shelves extending some way from the shore. These provide extensive shallows sunlit down to the seafloor, allowing for photosynthesis and enabling habitats for seagrass meadows, coral reefs, kelp forests and other benthic life. Further from shore the continental shelf slopes towards deep water. Wind blowing at the ocean surface or deep ocean currents can result in cold and nutrient rich waters from abyssal depths moving up the continental slopes. This can result in upwellings along the outer edges of continental shelves, providing conditions for phytoplankton blooms.

Water evaporated by the sun from the surface of the ocean can precipitate on land and eventually return to the ocean as runoff or discharge from rivers, enriched with nutrients as well as pollutants. As rivers discharge into estuaries, freshwater mixes with saltwater and becomes brackish. This provides another shallow water habitat where mangrove forests and estuarine fish thrive. Overall, life in inland lakes can evolve with greater diversity than happens in the sea, because freshwater habitats are themselves diverse and compartmentalised in a way marine habitats are not. Some aquatic life, such as salmon and eels, migrate back and forth between freshwater and marine habitats. These migrations can result in exchanges of pathogens and have impacts on the way life evolves in the ocean.

Anthropogenic impacts[edit]

Global cumulative human impact on the ocean[426]

Human activities affect marine life and marine habitats through overfishing, pollution, acidification and the introduction of invasive species. These impact marine ecosystems and food webs and may result in consequences as yet unrecognised for the biodiversity and continuation of marine life forms.[427]

Biodiversity and extinction events[edit]

Apparent marine fossil diversity during the Phanerozoic[428]
CambrianOrdovicianSilurianDevonianCarboniferousPermianTriassicJurassicCretaceousPaleogeneNeogene
Marine extinction intensity during the Phanerozoic
%
Millions of years ago
(H)
K–Pg
Tr–J
P–Tr
Cap
Late D
O–S
CambrianOrdovicianSilurianDevonianCarboniferousPermianTriassicJurassicCretaceousPaleogeneNeogene
Apparent extinction intensity, i.e. the fraction of genera going extinct at any given time as reconstructed from the fossil record (excluding the current Holocene extinction event)

Biodiversity is the result of over three billion years of evolution. Until approximately 600 million years ago, all life consisted of archaea, bacteria, protozoans and similar single-celled organisms. The history of biodiversity during the Phanerozoic (the last 540 million years), starts with rapid growth during the Cambrian explosion – a period during which nearly every phylum of multicellular organisms first appeared. Over the next 400 million years or so, invertebrate diversity showed little overall trend and vertebrate diversity shows an overall exponential trend.[429]

However, more than 99 percent of all species that ever lived on Earth, amounting to over five billion species,[430] are estimated to be extinct.[431][432] These extinctions occur at an uneven rate. The dramatic rise in diversity has been marked by periodic, massive losses of diversity classified as mass extinction events.[429] Mass extinction events occur when life undergoes precipitous global declines. Most diversity and biomass on earth is found among the microorganisms, which are difficult to measure. Recorded extinction events are therefore based on the more easily observed changes in the diversity and abundance of larger multicellular organisms, rather than the total diversity and abundance of life.[433] Marine fossils are mostly used to measure extinction rates because of their superior fossil record and stratigraphic range compared to land organisms.

Based on the fossil record, the background rate of extinctions on Earth is about two to five taxonomic families of marine animals every million years. The Great Oxygenation Event was perhaps the first major extinction event. Since the Cambrian explosion five further major mass extinctions have significantly exceeded the background extinction rate.[434] The worst was the Permian-Triassic extinction event, 251 million years ago. Vertebrates took 30 million years to recover from this event.[435] In addition to these major mass extinctions there are numerous minor ones, as well as the current ongoing mass-extinction caused by human activity, the Holocene extinction sometimes called the "sixth extinction".

See also[edit]

  • Blue Planet – British nature documentary series - David Attenborough
    • Blue Planet II
  • Census of Marine Life
  • Colonization of land
  • Taxonomy of invertebrates – System of classification of animals with emphasis on the invertebrates

Notes[edit]

  1. ^ This is the measurement taken by the vessel Kaikō in March 1995 and is considered the most accurate measurement to date. See the Challenger Deep article for more details.
  2. ^ Myxozoa were thought to be an exception, but are now thought to be heavily modified members of the Cnidaria. Jímenez-Guri, Eva; Philippe, Hervé; Okamura, Beth; Holland, Peter W. H. (6 July 2007). "Buddenbrockia Is a Cnidarian Worm". Science. 317 (5834): 116–118. Bibcode:2007Sci...317..116J. doi:10.1126/science.1142024. ISSN 0036-8075. PMID 17615357. S2CID 5170702.

References[edit]

  1. ^ a b Cavicchioli, Ricardo; Ripple, William J.; Timmis, Kenneth N.; Azam, Farooq; Bakken, Lars R.; Baylis, Matthew; Behrenfeld, Michael J.; Boetius, Antje; Boyd, Philip W.; Classen, Aimée T.; Crowther, Thomas W.; Danovaro, Roberto; Foreman, Christine M.; Huisman, Jef; Hutchins, David A.; Jansson, Janet K.; Karl, David M.; Koskella, Britt; Mark Welch, David B.; Martiny, Jennifer B. H.; Moran, Mary Ann; Orphan, Victoria J.; Reay, David S.; Remais, Justin V.; Rich, Virginia I.; Singh, Brajesh K.; Stein, Lisa Y.; Stewart, Frank J.; Sullivan, Matthew B.; et al. (2019). "Scientists' warning to humanity: Microorganisms and climate change". Nature Reviews Microbiology. 17 (9): 569–586. doi:10.1038/s41579-019-0222-5. PMC 7136171. PMID 31213707. Material was copied from this source, which is available under a Creative Commons Attribution 4.0 International License.
  2. ^ a b c "National Oceanic and Atmospheric Administration – Ocean". NOAA. Retrieved 20 February 2019.
  3. ^ Tiny Fish May Be Ancestor of Nearly All Living Vertebrates Live Science, 11 June 2014.
  4. ^ Drogin, Bob (2 August 2009). "Mapping an ocean of species". Los Angeles Times. Retrieved 18 August 2009.
  5. ^ Paul, Gregory S. (2010). "The Evolution of Dinosaurs and their World". The Princeton Field Guide to Dinosaurs. Princeton: Princeton University Press. p. 19.
  6. ^ Bortolotti, Dan (2008). Wild Blue: A Natural History of the World's Largest Animal. St. Martin's Press.
  7. ^ a b c Bar-On, YM; Phillips, R; Milo, R (2018). "The biomass distribution on Earth". PNAS. 115 (25): 6506–6511. doi:10.1073/pnas.1711842115. PMC 6016768. PMID 29784790.
  8. ^ Census Of Marine Life Accessed 29 October 2020.
  9. ^ Xiao-feng, Pang (2014) Water: Molecular Structure And Properties, chapter 5, pp. 390–461, World Scientific. ISBN 9789814440448
  10. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 620. ISBN 978-0-08-037941-8.
  11. ^ "Water, the Universal Solvent". USGS. Archived from the original on 9 July 2017. Retrieved 27 June 2017.
  12. ^ Reece, Jane B. (31 October 2013). Campbell Biology (10 ed.). Pearson. p. 48. ISBN 9780321775658.
  13. ^ Reece, Jane B. (31 October 2013). Campbell Biology (10 ed.). Pearson. p. 44. ISBN 9780321775658.
  14. ^ Collins J. C. (1991) The Matrix of Life: A View of Natural Molecules from the Perspective of Environmental Water Molecular Presentations. ISBN 9780962971907.
  15. ^ "7,000 m Class Remotely Operated Vehicle KAIKO 7000". Japan Agency for Marine-Earth Science and Technology (JAMSTEC). Retrieved 7 June 2008.
  16. ^ How many oceans are there? NOAA. Updated: 9 April 2020.
  17. ^ Charette, Matthew A.; Smith, Walter H. F. (June 2010). "The Volume of Earth's Ocean" (PDF). Oceanography. 23 (2): 112–14. doi:10.5670/oceanog.2010.51. Archived from the original (PDF) on 2 August 2013. Retrieved 6 June 2013.
  18. ^ "sphere depth of the ocean – hydrology". Encyclopædia Britannica. Retrieved 12 April 2015.
  19. ^ "Third rock from the Sun – restless Earth". NASA's Cosmos. Retrieved 12 April 2015.
  20. ^ Perlman, Howard (17 March 2014). "The World's Water". USGS Water-Science School. Retrieved 12 April 2015.
  21. ^ Kennish, Michael J. (2001). Practical handbook of marine science. Marine science series (3rd ed.). CRC Press. p. 35. ISBN 978-0-8493-2391-1.
  22. ^ "Why is the ocean salty?".
  23. ^ Mullen, Leslie (11 June 2002). "Salt of the Early Earth". NASA Astrobiology Magazine. Archived from the original on 22 July 2007. Retrieved 14 March 2007.
  24. ^ Morris, Ron M. "Oceanic Processes". NASA Astrobiology Magazine. Archived from the original on 15 April 2009. Retrieved 14 March 2007.
  25. ^ Scott, Michon (24 April 2006). "Earth's Big heat Bucket". NASA Earth Observatory. Retrieved 14 March 2007.
  26. ^ Sample, Sharron (21 June 2005). "Sea Surface Temperature". NASA. Archived from the original on 3 April 2013. Retrieved 21 April 2007.
  27. ^ "Volumes of the World's Oceans from ETOPO1". NOAA. Archived from the original on 11 March 2015. Retrieved 20 February 2019.CS1 maint: bot: original URL status unknown (link)
  28. ^ Planet "Earth": We Should Have Called It "Sea" Quote Invertigator, 25 January 2017.
  29. ^ Unveiling Planet Ocean NASA Science, 14 March 2002.
  30. ^ Dyches, Preston; Brown, Dwayne (12 May 2015). "NASA Research Reveals Europa's Mystery Dark Material Could Be Sea Salt". NASA. Retrieved 12 May 2015.
  31. ^ "Water near surface of a Jupiter moon only temporary".
  32. ^ Tritt, Charles S. (2002). "Possibility of Life on Europa". Milwaukee School of Engineering. Archived from the original on 9 June 2007. Retrieved 10 August 2007.
  33. ^ Schulze-Makuch, Dirk; Irwin, Louis N. (2001). "Alternative Energy Sources Could Support Life on Europa" (PDF). Departments of Geological and Biological Sciences, University of Texas at El Paso. Archived from the original (PDF) on 3 July 2006. Retrieved 21 December 2007.
  34. ^ Friedman, Louis (14 December 2005). "Projects: Europa Mission Campaign". The Planetary Society. Archived from the original on 11 August 2011. Retrieved 8 August 2011.
  35. ^ Ocean Within Enceladus May Harbor Hydrothermal Activity, NASA Press Release. 11 March 2015.
  36. ^ "Age of the Earth". United States Geological Survey. 9 July 2007. Retrieved 31 May 2015.
  37. ^ Dalrymple 2001, pp. 205–221
  38. ^ Manhesa, Gérard; Allègre, Claude J.; Dupréa, Bernard; Hamelin, Bruno (May 1980). "Lead isotope study of basic-ultrabasic layered complexes: Speculations about the age of the earth and primitive mantle characteristics". Earth and Planetary Science Letters. 47 (3): 370–382. Bibcode:1980E&PSL..47..370M. doi:10.1016/0012-821X(80)90024-2. ISSN 0012-821X.
  39. ^ Schopf, J. William; Kudryavtsev, Anatoliy B.; Czaja, Andrew D.; Tripathi, Abhishek B. (5 October 2007). "Evidence of Archean life: Stromatolites and microfossils". Precambrian Research. 158 (3–4): 141–155. Bibcode:2007PreR..158..141S. doi:10.1016/j.precamres.2007.04.009. ISSN 0301-9268.
  40. ^ Raven & Johnson 2002, p. 68
  41. ^ Baumgartner, R. J.; et al. (2019). "Nano−porous pyrite and organic matter in 3.5-billion-year-old stromatolites record primordial life" (PDF). Geology. 47 (11): 1039–1043. Bibcode:2019Geo....47.1039B. doi:10.1130/G46365.1.
  42. ^ Earliest signs of life: Scientists find microbial remains in ancient rocks Phys.org. 26 September 2019.
  43. ^ Ohtomo, Yoko; Kakegawa, Takeshi; Ishida, Akizumi; et al. (January 2014). "Evidence for biogenic graphite in early Archaean Isua metasedimentary rocks". Nature Geoscience. 7 (1): 25–28. Bibcode:2014NatGe...7...25O. doi:10.1038/ngeo2025. ISSN 1752-0894.
  44. ^ a b Borenstein, Seth (19 October 2015). "Hints of life on what was thought to be desolate early Earth". Associated Press. Retrieved 9 October 2018.
  45. ^ Bell, Elizabeth A.; Boehnike, Patrick; Harrison, T. Mark; et al. (24 November 2015). "Potentially biogenic carbon preserved in a 4.1 billion-year-old zircon" (PDF). Proceedings of the National Academy of Sciences of the United States of America. 112 (47): 14518–14521. Bibcode:2015PNAS..11214518B. doi:10.1073/pnas.1517557112. ISSN 0027-8424. PMC 4664351. PMID 26483481. Retrieved 30 December 2015.
  46. ^ Penny, David; Poole, Anthony (December 1999). "The nature of the last universal common ancestor". Current Opinion in Genetics & Development. 9 (6): 672–677. doi:10.1016/S0959-437X(99)00020-9. ISSN 0959-437X. PMID 10607605.
  47. ^ Theobald, Douglas L. (13 May 2010). "A formal test of the theory of universal common ancestry". Nature. 465 (7295): 219–222. Bibcode:2010Natur.465..219T. doi:10.1038/nature09014. ISSN 0028-0836. PMID 20463738. S2CID 4422345.
  48. ^ Doolittle, W. Ford (February 2000). "Uprooting the Tree of Life" (PDF). Scientific American. 282 (2): 90–95. Bibcode:2000SciAm.282b..90D. doi:10.1038/scientificamerican0200-90. ISSN 0036-8733. PMID 10710791. Archived from the original (PDF) on 7 September 2006. Retrieved 5 April 2015.
  49. ^ Peretó, Juli (March 2005). "Controversies on the origin of life" (PDF). International Microbiology. 8 (1): 23–31. ISSN 1139-6709. PMID 15906258. Archived from the original (PDF) on 24 August 2015.
  50. ^ Joyce, Gerald F. (11 July 2002). "The antiquity of RNA-based evolution". Nature. 418 (6894): 214–221. Bibcode:2002Natur.418..214J. doi:10.1038/418214a. ISSN 0028-0836. PMID 12110897. S2CID 4331004.
  51. ^ Trevors, Jack T.; Psenner, Roland (December 2001). "From self-assembly of life to present-day bacteria: a possible role for nanocells". FEMS Microbiology Reviews. 25 (5): 573–582. doi:10.1111/j.1574-6976.2001.tb00592.x. ISSN 1574-6976. PMID 11742692.
  52. ^ Wade, Nicholas (25 July 2016). "Meet Luca, the Ancestor of All Living Things". New York Times. Retrieved 25 July 2016.
  53. ^ Bapteste, Eric; Walsh, David A. (June 2005). "Does the 'Ring of Life' ring true?". Trends in Microbiology. 13 (6): 256–261. doi:10.1016/j.tim.2005.03.012. ISSN 0966-842X. PMID 15936656.
  54. ^ Darwin 1859, p. 1
  55. ^ Doolittle, W. Ford; Bapteste, Eric (13 February 2007). "Pattern pluralism and the Tree of Life hypothesis". Proceedings of the National Academy of Sciences of the United States of America. 104 (7): 2043–2049. Bibcode:2007PNAS..104.2043D. doi:10.1073/pnas.0610699104. ISSN 0027-8424. PMC 1892968. PMID 17261804.
  56. ^ Kunin, Victor; Goldovsky, Leon; Darzentas, Nikos; Ouzounis, Christos A. (July 2005). "The net of life: Reconstructing the microbial phylogenetic network". Genome Research. 15 (7): 954–959. doi:10.1101/gr.3666505. ISSN 1088-9051. PMC 1172039. PMID 15965028.
  57. ^ Jablonski, David (25 June 1999). "The Future of the Fossil Record". Science. 284 (5423): 2114–2116. doi:10.1126/science.284.5423.2114. ISSN 0036-8075. PMID 10381868. S2CID 43388925.
  58. ^ Ciccarelli, Francesca D.; Doerks, Tobias; von Mering, Christian; et al. (3 March 2006). "Toward Automatic Reconstruction of a Highly Resolved Tree of Life". Science. 311 (5765): 1283–1287. Bibcode:2006Sci...311.1283C. CiteSeerX 10.1.1.381.9514. doi:10.1126/science.1123061. ISSN 0036-8075. PMID 16513982. S2CID 1615592.
  59. ^ Mason, Stephen F. (6 September 1984). "Origins of biomolecular handedness". Nature. 311 (5981): 19–23. Bibcode:1984Natur.311...19M. doi:10.1038/311019a0. ISSN 0028-0836. PMID 6472461. S2CID 103653.
  60. ^ Wolf, Yuri I.; Rogozin, Igor B.; Grishin, Nick V.; Koonin, Eugene V. (1 September 2002). "Genome trees and the tree of life". Trends in Genetics. 18 (9): 472–479. doi:10.1016/S0168-9525(02)02744-0. ISSN 0168-9525. PMID 12175808.
  61. ^ Varki, Ajit; Altheide, Tasha K. (December 2005). "Comparing the human and chimpanzee genomes: searching for needles in a haystack" (PDF). Genome Research. 15 (12): 1746–1758. doi:10.1101/gr.3737405. ISSN 1088-9051. PMID 16339373.
  62. ^ a b Cavalier-Smith, Thomas (29 June 2006). "Cell evolution and Earth history: stasis and revolution". Philosophical Transactions of the Royal Society B: Biological Sciences. 361 (1470): 969–1006. doi:10.1098/rstb.2006.1842. ISSN 0962-8436. PMC 1578732. PMID 16754610.
  63. ^ Schopf, J. William (29 June 2006). "Fossil evidence of Archaean life". Philosophical Transactions of the Royal Society B: Biological Sciences. 361 (1470): 869–885. doi:10.1098/rstb.2006.1834. ISSN 0962-8436. PMC 1578735. PMID 16754604.
    • Altermann, Wladyslaw; Kazmierczak, Józef (November 2003). "Archean microfossils: a reappraisal of early life on Earth". Research in Microbiology. 154 (9): 611–617. doi:10.1016/j.resmic.2003.08.006. ISSN 0923-2508. PMID 14596897.
  64. ^ Schopf, J. William (19 July 1994). "Disparate rates, differing fates: tempo and mode of evolution changed from the Precambrian to the Phanerozoic". Proceedings of the National Academy of Sciences of the United States of America. 91 (15): 6735–6742. Bibcode:1994PNAS...91.6735S. doi:10.1073/pnas.91.15.6735. ISSN 0027-8424. PMC 44277. PMID 8041691.
  65. ^ Poole, Anthony M.; Penny, David (January 2007). "Evaluating hypotheses for the origin of eukaryotes". BioEssays. 29 (1): 74–84. doi:10.1002/bies.20516. ISSN 0265-9247. PMID 17187354.
  66. ^ a b Dyall, Sabrina D.; Brown, Mark T.; Johnson, Patricia J. (9 April 2004). "Ancient Invasions: From Endosymbionts to Organelles". Science. 304 (5668): 253–257. Bibcode:2004Sci...304..253D. doi:10.1126/science.1094884. ISSN 0036-8075. PMID 15073369. S2CID 19424594.
  67. ^ Martin, William (October 2005). "The missing link between hydrogenosomes and mitochondria". Trends in Microbiology. 13 (10): 457–459. doi:10.1016/j.tim.2005.08.005. ISSN 0966-842X. PMID 16109488.
  68. ^ Lang, B. Franz; Gray, Michael W.; Burger, Gertraud (December 1999). "Mitochondrial genome evolution and the origin of eukaryotes". Annual Review of Genetics. 33: 351–397. doi:10.1146/annurev.genet.33.1.351. ISSN 0066-4197. PMID 10690412.
    • McFadden, Geoffrey Ian (1 December 1999). "Endosymbiosis and evolution of the plant cell". Current Opinion in Plant Biology. 2 (6): 513–519. doi:10.1016/S1369-5266(99)00025-4. ISSN 1369-5266. PMID 10607659.
  69. ^ DeLong, Edward F.; Pace, Norman R. (1 August 2001). "Environmental Diversity of Bacteria and Archaea". Systematic Biology. 50 (4): 470–478. CiteSeerX 10.1.1.321.8828. doi:10.1080/106351501750435040. ISSN 1063-5157. PMID 12116647.
  70. ^ Kaiser, Dale (December 2001). "Building a multicellular organism". Annual Review of Genetics. 35: 103–123. doi:10.1146/annurev.genet.35.102401.090145. ISSN 0066-4197. PMID 11700279. S2CID 18276422.
  71. ^ Zimmer, Carl (7 January 2016). "Genetic Flip Helped Organisms Go From One Cell to Many". The New York Times. Retrieved 7 January 2016.
  72. ^ Valentine, James W.; Jablonski, David; Erwin, Douglas H. (1 March 1999). "Fossils, molecules and embryos: new perspectives on the Cambrian explosion". Development. 126 (5): 851–859. doi:10.1242/dev.126.5.851. ISSN 0950-1991. PMID 9927587. Retrieved 30 December 2014.
  73. ^ Ohno, Susumu (January 1997). "The reason for as well as the consequence of the Cambrian explosion in animal evolution". Journal of Molecular Evolution. 44 (Suppl. 1): S23–S27. Bibcode:1997JMolE..44S..23O. doi:10.1007/PL00000055. ISSN 0022-2844. PMID 9071008. S2CID 21879320.
    • Valentine, James W.; Jablonski, David (2003). "Morphological and developmental macroevolution: a paleontological perspective". The International Journal of Developmental Biology. 47 (7–8): 517–522. ISSN 0214-6282. PMID 14756327. Retrieved 30 December 2014.
  74. ^ Wellman, Charles H.; Osterloff, Peter L.; Mohiuddin, Uzma (2003). "Fragments of the earliest land plants" (PDF). Nature. 425 (6955): 282–285. Bibcode:2003Natur.425..282W. doi:10.1038/nature01884. PMID 13679913. S2CID 4383813.
  75. ^ Barton, Nicholas (2007). Evolution. pp. 273–274. ISBN 9780199226320. Retrieved 30 September 2012.
  76. ^ Waters, Elizabeth R. (December 2003). "Molecular adaptation and the origin of land plants". Molecular Phylogenetics and Evolution. 29 (3): 456–463. doi:10.1016/j.ympev.2003.07.018. ISSN 1055-7903. PMID 14615186.
  77. ^ Mayhew, Peter J. (August 2007). "Why are there so many insect species? Perspectives from fossils and phylogenies". Biological Reviews. 82 (3): 425–454. doi:10.1111/j.1469-185X.2007.00018.x. ISSN 1464-7931. PMID 17624962. S2CID 9356614.
  78. ^ Carroll, Robert L. (May 2007). "The Palaeozoic Ancestry of Salamanders, Frogs and Caecilians". Zoological Journal of the Linnean Society. 150 (Supplement s1): 1–140. doi:10.1111/j.1096-3642.2007.00246.x. ISSN 1096-3642.
  79. ^ Wible, John R.; Rougier, Guillermo W.; Novacek, Michael J.; Asher, Robert J. (21 June 2007). "Cretaceous eutherians and Laurasian origin for placental mammals near the K/T boundary". Nature. 447 (7147): 1003–1006. Bibcode:2007Natur.447.1003W. doi:10.1038/nature05854. ISSN 0028-0836. PMID 17581585. S2CID 4334424.
  80. ^ Witmer, Lawrence M. (28 July 2011). "Palaeontology: An icon knocked from its perch". Nature. 475 (7357): 458–459. doi:10.1038/475458a. ISSN 0028-0836. PMID 21796198. S2CID 205066360.
  81. ^ Schloss, Patrick D.; Handelsman, Jo (December 2004). "Status of the Microbial Census". Microbiology and Molecular Biology Reviews. 68 (4): 686–691. doi:10.1128/MMBR.68.4.686-691.2004. ISSN 1092-2172. PMC 539005. PMID 15590780.
  82. ^ Miller & Spoolman 2012, p. 62
  83. ^ Mora, Camilo; Tittensor, Derek P.; Adl, Sina; et al. (23 August 2011). "How Many Species Are There on Earth and in the Ocean?". PLOS Biology. 9 (8): e1001127. doi:10.1371/journal.pbio.1001127. ISSN 1545-7885. PMC 3160336. PMID 21886479.
  84. ^ Madigan M; Martinko J, eds. (2006). Brock Biology of Microorganisms (13th ed.). Pearson Education. p. 1096. ISBN 978-0-321-73551-5.
  85. ^ Rybicki EP (1990). "The classification of organisms at the edge of life, or problems with virus systematics". South African Journal of Science. 86: 182–6. ISSN 0038-2353.
  86. ^ Lwoff A (1956). "The concept of virus". Journal of General Microbiology. 17 (2): 239–53. doi:10.1099/00221287-17-2-239. PMID 13481308.
  87. ^ 2002 WHO mortality data Accessed 20 January 2007
  88. ^ "Functions of global ocean microbiome key to understanding environmental changes". www.sciencedaily.com. University of Georgia. 10 December 2015. Retrieved 11 December 2015.
  89. ^ Suttle, C.A. (2005). "Viruses in the Sea". Nature. 437 (9): 356–361. Bibcode:2005Natur.437..356S. doi:10.1038/nature04160. PMID 16163346. S2CID 4370363.
  90. ^ Shors p. 5
  91. ^ Shors p. 593
  92. ^ a b c Suttle CA. Marine viruses—major players in the global ecosystem. Nature Reviews Microbiology. 2007;5(10):801–12. doi:10.1038/nrmicro1750. PMID 17853907.
  93. ^ Living Bacteria Are Riding Earth’s Air Currents Smithsonian Magazine, 11 January 2016.
  94. ^ Robbins, Jim (13 April 2018). "Trillions Upon Trillions of Viruses Fall From the Sky Each Day". The New York Times. Retrieved 14 April 2018.
  95. ^ Reche, Isabel; D’Orta, Gaetano; Mladenov, Natalie; Winget, Danielle M; Suttle, Curtis A (29 January 2018). "Deposition rates of viruses and bacteria above the atmospheric boundary layer". ISME Journal. 12 (4): 1154–1162. doi:10.1038/s41396-017-0042-4. PMC 5864199. PMID 29379178.
  96. ^ Staff (2014). "The Biosphere". Aspen Global Change Institute. Retrieved 10 November 2014.
  97. ^ a b c Choi, Charles Q. (17 March 2013). "Microbes Thrive in Deepest Spot on Earth". LiveScience. Retrieved 17 March 2013.
  98. ^ Glud, Ronnie; Wenzhöfer, Frank; Middelboe, Mathias; Oguri, Kazumasa; Turnewitsch, Robert; Canfield, Donald E.; Kitazato, Hiroshi (17 March 2013). "High rates of microbial carbon turnover in sediments in the deepest oceanic trench on Earth". Nature Geoscience. 6 (4): 284–288. Bibcode:2013NatGe...6..284G. doi:10.1038/ngeo1773.
  99. ^ Oskin, Becky (14 March 2013). "Intraterrestrials: Life Thrives in Ocean Floor". LiveScience. Retrieved 17 March 2013.
  100. ^ Morelle, Rebecca (15 December 2014). "Microbes discovered by deepest marine drill analysed". BBC News. Retrieved 15 December 2014.
  101. ^ Takai K; Nakamura K; Toki T; Tsunogai U; et al. (2008). "Cell proliferation at 122°C and isotopically heavy CH4 production by a hyperthermophilic methanogen under high-pressure cultivation". Proceedings of the National Academy of Sciences of the United States of America. 105 (31): 10949–54. Bibcode:2008PNAS..10510949T. doi:10.1073/pnas.0712334105. PMC 2490668. PMID 18664583.
  102. ^ Fox, Douglas (20 August 2014). "Lakes under the ice: Antarctica's secret garden". Nature. 512 (7514): 244–246. Bibcode:2014Natur.512..244F. doi:10.1038/512244a. PMID 25143097.
  103. ^ Mack, Eric (20 August 2014). "Life Confirmed Under Antarctic Ice; Is Space Next?". Forbes. Retrieved 21 August 2014.
  104. ^ Wimmer E, Mueller S, Tumpey TM, Taubenberger JK. Synthetic viruses: a new opportunity to understand and prevent viral disease. Nature Biotechnology. 2009;27(12):1163–72. doi:10.1038/nbt.1593. PMID 20010599.
  105. ^ Koonin EV, Senkevich TG, Dolja VV. The ancient Virus World and evolution of cells. Biology Direct. 2006;1:29. doi:10.1186/1745-6150-1-29. PMID 16984643.
  106. ^ Collier, Leslie; Balows, Albert; Sussman, Max (1998) Topley and Wilson's Microbiology and Microbial Infections ninth edition, Volume 1, Virology, volume editors: Mahy, Brian and Collier, Leslie. Arnold. Pages 33–37. ISBN 0-340-66316-2.
  107. ^ Iyer LM, Balaji S, Koonin EV, Aravind L. Evolutionary genomics of nucleo-cytoplasmic large DNA viruses. Virus Research. 2006;117(1):156–84. doi:10.1016/j.virusres.2006.01.009. PMID 16494962.
  108. ^ Sanjuán R, Nebot MR, Chirico N, Mansky LM, Belshaw R. Viral mutation rates. Journal of Virology. 2010;84(19):9733–48. doi:10.1128/JVI.00694-10. PMID 20660197.
  109. ^ In: Mahy WJ, Van Regenmortel MHV. Desk Encyclopedia of General Virology. Oxford: Academic Press; 2009. ISBN 0-12-375146-2. p. 28.
  110. ^ a b Canchaya C, Fournous G, Chibani-Chennoufi S, Dillmann ML, Brüssow H. Phage as agents of lateral gene transfer. Current Opinion in Microbiology. 2003;6(4):417–24. doi:10.1016/S1369-5274(03)00086-9. PMID 12941415.
  111. ^ Are viruses alive? The replicator paradigm sheds decisive light on an old but misguided question. Studies in History and Philosophy of Biological and Biomedical Sciences. 2016. doi:10.1016/j.shpsc.2016.02.016. PMID 26965225.
  112. ^ Koonin, E. V.; Starokadomskyy, P. (7 March 2016). "Are viruses alive? The replicator paradigm sheds decisive light on an old but misguided question". Studies in History and Philosophy of Biological and Biomedical Sciences. 59: 125–34. doi:10.1016/j.shpsc.2016.02.016. PMC 5406846. PMID 26965225.
  113. ^ Rybicki, EP. The classification of organisms at the edge of life, or problems with virus systematics. South African Journal of Science. 1990;86:182–186.
  114. ^ a b Mann, NH (17 May 2005). "The Third Age of Phage". PLOS Biology. 3 (5): 753–755. doi:10.1371/journal.pbio.0030182. PMC 1110918. PMID 15884981.
  115. ^ Wommack KE, Colwell RR. Virioplankton: viruses in aquatic ecosystems. Microbiology and Molecular Biology Reviews. 2000;64(1):69–114. doi:10.1128/MMBR.64.1.69-114.2000. PMID 10704475.
  116. ^ Suttle CA. Viruses in the sea. Nature. 2005;437:356–361. doi:10.1038/nature04160. PMID 16163346. Bibcode:2005Natur.437..356S.
  117. ^ Bergh O, Børsheim KY, Bratbak G, Heldal M. High abundance of viruses found in aquatic environments. Nature. 1989;340(6233):467–8. doi:10.1038/340467a0. PMID 2755508. Bibcode:1989Natur.340..467B.
  118. ^ Wigington CH, Sonderegger D, Brussaard CPD, Buchan A, Finke JF, Fuhrman JA, Lennon JT, Middelboe M, Suttle CA, Stock C, Wilson WH, Wommack KE, Wilhelm SW, Weitz JS. Re-examination of the relationship between marine virus and microbial cell abundances. Nature Microbiology. 2016;1:15024. doi:10.1038/nmicrobiol.2015.24. PMID 27572161.
  119. ^ Krupovic M, Bamford DH (2007). "Putative prophages related to lytic tailless marine dsDNA phage PM2 are widespread in the genomes of aquatic bacteria". BMC Genomics. 8: 236. doi:10.1186/1471-2164-8-236. PMC 1950889. PMID 17634101.
  120. ^ Xue H, Xu Y, Boucher Y, Polz MF (2012). "High frequency of a novel filamentous phage, VCY φ, within an environmental Vibrio cholerae population". Applied and Environmental Microbiology. 78 (1): 28–33. doi:10.1128/AEM.06297-11. PMC 3255608. PMID 22020507.
  121. ^ Roux S, Krupovic M, Poulet A, Debroas D, Enault F (2012). "Evolution and diversity of the Microviridae viral family through a collection of 81 new complete genomes assembled from virome reads". PLOS ONE. 7 (7): e40418. Bibcode:2012PLoSO...740418R. doi:10.1371/journal.pone.0040418. PMC 3394797. PMID 22808158.
  122. ^ Suttle CA. Viruses in the sea. Nature. 2005;437(7057):356–61. doi:10.1038/nature04160. PMID 16163346. Bibcode:2005Natur.437..356S.
  123. ^ www.cdc.gov. Harmful Algal Blooms: Red Tide: Home [Retrieved 2014-12-19].
  124. ^ Lawrence CM, Menon S, Eilers BJ, et al.. Structural and functional studies of archaeal viruses. Journal of Biological Chemistry. 2009;284(19):12599–603. doi:10.1074/jbc.R800078200. PMID 19158076.
  125. ^ Prangishvili D, Forterre P, Garrett RA. Viruses of the Archaea: a unifying view. Nature Reviews Microbiology. 2006;4(11):837–48. doi:10.1038/nrmicro1527. PMID 17041631.
  126. ^ Prangishvili D, Garrett RA. Exceptionally diverse morphotypes and genomes of crenarchaeal hyperthermophilic viruses. Biochemical Society Transactions. 2004;32(Pt 2):204–8. doi:10.1042/BST0320204. PMID 15046572.
  127. ^ Forterre P, Philippe H. The last universal common ancestor (LUCA), simple or complex?. The Biological Bulletin. 1999;196(3):373–5; discussion 375–7. doi:10.2307/1542973. PMID 11536914.
  128. ^ Fredrickson JK, Zachara JM, Balkwill DL, Kennedy D, Li SM, Kostandarithes HM, Daly MJ, Romine MF, Brockman FJ (2004). "Geomicrobiology of high-level nuclear waste-contaminated vadose sediments at the Hanford site, Washington state". Applied and Environmental Microbiology. 70 (7): 4230–41. doi:10.1128/AEM.70.7.4230-4241.2004. PMC 444790. PMID 15240306.
  129. ^ Woese CR, Kandler O, Wheelis ML (1990). "Towards a natural system of organisms: proposal for the domains Archaea, Bacteria, and Eucarya". Proceedings of the National Academy of Sciences of the United States of America. 87 (12): 4576–9. Bibcode:1990PNAS...87.4576W. doi:10.1073/pnas.87.12.4576. PMC 54159. PMID 2112744.
  130. ^ Schopf JW (1994). "Disparate rates, differing fates: tempo and mode of evolution changed from the Precambrian to the Phanerozoic". Proceedings of the National Academy of Sciences of the United States of America. 91 (15): 6735–42. Bibcode:1994PNAS...91.6735S. doi:10.1073/pnas.91.15.6735. PMC 44277. PMID 8041691.
  131. ^ DeLong EF, Pace NR (2001). "Environmental diversity of bacteria and archaea". Systematic Biology. 50 (4): 470–8. CiteSeerX 10.1.1.321.8828. doi:10.1080/106351501750435040. PMID 12116647.
  132. ^ Brown JR, Doolittle WF (1997). "Archaea and the prokaryote-to-eukaryote transition". Microbiology and Molecular Biology Reviews. 61 (4): 456–502. doi:10.1128/.61.4.456-502.1997. PMC 232621. PMID 9409149.
  133. ^ Poole AM, Penny D (2007). "Evaluating hypotheses for the origin of eukaryotes". BioEssays. 29 (1): 74–84. doi:10.1002/bies.20516. PMID 17187354.
  134. ^ Lang BF, Gray MW, Burger G (1999). "Mitochondrial genome evolution and the origin of eukaryotes". Annual Review of Genetics. 33: 351–97. doi:10.1146/annurev.genet.33.1.351. PMID 10690412.
  135. ^ McFadden GI (1999). "Endosymbiosis and evolution of the plant cell". Current Opinion in Plant Biology. 2 (6): 513–9. doi:10.1016/S1369-5266(99)00025-4. PMID 10607659.
  136. ^ Patrick J. Keeling (2004). "Diversity and evolutionary history of plastids and their hosts". American Journal of Botany. 91 (10): 1481–1493. doi:10.3732/ajb.91.10.1481. PMID 21652304.
  137. ^ "The largest Bacterium: Scientist discovers new bacterial life form off the African coast", Max Planck Institute for Marine Microbiology, 8 April 1999, archived from the original on 20 January 2010
  138. ^ List of Prokaryotic names with Standing in Nomenclature - Genus Thiomargarita
  139. ^ Bang C, Schmitz RA (2015). "Archaea associated with human surfaces: not to be underestimated". FEMS Microbiology Reviews. 39 (5): 631–48. doi:10.1093/femsre/fuv010. PMID 25907112.
  140. ^ Archaea Online Etymology Dictionary. Retrieved 17 August 2016.
  141. ^ Pace NR (May 2006). "Time for a change". Nature. 441 (7091): 289. Bibcode:2006Natur.441..289P. doi:10.1038/441289a. PMID 16710401. S2CID 4431143.
  142. ^ Stoeckenius W (1 October 1981). "Walsby's square bacterium: fine structure of an orthogonal procaryote". Journal of Bacteriology. 148 (1): 352–60. doi:10.1128/JB.148.1.352-360.1981. PMC 216199. PMID 7287626.
  143. ^ Whittaker, R.H.; Margulis, L. (1978). "Protist classification and the kingdoms of organisms". Biosystems. 10 (1–2): 3–18. doi:10.1016/0303-2647(78)90023-0. PMID 418827.
  144. ^ Faure, E; Not, F; Benoiston, AS; Labadie, K; Bittner, L; Ayata, SD (2019). "Mixotrophic protists display contrasted biogeographies in the global ocean" (PDF). ISME Journal. 13 (4): 1072–1083. doi:10.1038/s41396-018-0340-5. PMC 6461780. PMID 30643201.
  145. ^ a b Leles, S.G.; Mitra, A.; Flynn, K.J.; Stoecker, D.K.; Hansen, P.J.; Calbet, A.; McManus, G.B.; Sanders, R.W.; Caron, D.A.; Not, F.; Hallegraeff, G.M. (1860). "Oceanic protists with different forms of acquired phototrophy display contrasting biogeographies and abundance". Proceedings of the Royal Society B: Biological Sciences. 284 (1860): 20170664. doi:10.1098/rspb.2017.0664. PMC 5563798. PMID 28768886.
  146. ^ Budd, Graham E; Jensen, Sören (2017). "The origin of the animals and a 'Savannah' hypothesis for early bilaterian evolution". Biological Reviews. 92 (1): 446–473. doi:10.1111/brv.12239. PMID 26588818.
  147. ^ Cavalier-Smith T (December 1993). "Kingdom protozoa and its 18 phyla". Microbiological Reviews. 57 (4): 953–94. doi:10.1128/MMBR.57.4.953-994.1993. PMC 372943. PMID 8302218.
  148. ^ Corliss JO (1992). "Should there be a separate code of nomenclature for the protists?". BioSystems. 28 (1–3): 1–14. doi:10.1016/0303-2647(92)90003-H. PMID 1292654.
  149. ^ Slapeta J, Moreira D, López-García P (2005). "The extent of protist diversity: insights from molecular ecology of freshwater eukaryotes". Proceedings of the Royal Society B: Biological Sciences. 272 (1576): 2073–81. doi:10.1098/rspb.2005.3195. PMC 1559898. PMID 16191619.
  150. ^ Moreira D, López-García P (2002). "The molecular ecology of microbial eukaryotes unveils a hidden world" (PDF). Trends in Microbiology. 10 (1): 31–8. doi:10.1016/S0966-842X(01)02257-0. PMID 11755083.
  151. ^ a b The Air You're Breathing? A Diatom Made That
  152. ^ "More on Diatoms". University of California Museum of Paleontology. Archived from the original on 4 October 2012. Retrieved 27 June 2019.
  153. ^ Devreotes P (1989). "Dictyostelium discoideum: a model system for cell-cell interactions in development". Science. 245 (4922): 1054–8. Bibcode:1989Sci...245.1054D. doi:10.1126/science.2672337. PMID 2672337.
  154. ^ Matz, Mikhail V.; Tamara M. Frank; N. Justin Marshall; Edith A. Widder; Sonke Johnsen (9 December 2008). "Giant Deep-Sea Protist Produces Bilaterian-like Traces" (PDF). Current Biology. Elsevier Ltd. 18 (23): 1849–1854. doi:10.1016/j.cub.2008.10.028. PMID 19026540. S2CID 8819675.
  155. ^ Gooday, A. J.; Aranda da Silva, A.; Pawlowski, J. (1 December 2011). "Xenophyophores (Rhizaria, Foraminifera) from the Nazaré Canyon (Portuguese margin, NE Atlantic)". Deep-Sea Research Part II: Topical Studies in Oceanography. The Geology, Geochemistry, and Biology of Submarine Canyons West of Portugal. 58 (23–24): 2401–2419. Bibcode:2011DSRII..58.2401G. doi:10.1016/j.dsr2.2011.04.005.
  156. ^ Neil A C, Reece J B, Simon E J (2004) Essential biology with physiology Pearson/Benjamin Cummings, Page 291. ISBN 9780805375039
  157. ^ O'Malley MA, Simpson AG, Roger AJ (2012). "The other eukaryotes in light of evolutionary protistology". Biology & Philosophy. 28 (2): 299–330. doi:10.1007/s10539-012-9354-y. S2CID 85406712.
  158. ^ Adl SM, Simpson AG, Farmer MA, Andersen RA, Anderson OR, Barta JR, Bowser SS, Brugerolle G, Fensome RA, Fredericq S, James TY, Karpov S, Kugrens P, Krug J, Lane CE, Lewis LA, Lodge J, Lynn DH, Mann DG, McCourt RM, Mendoza L, Moestrup O, Mozley-Standridge SE, Nerad TA, Shearer CA, Smirnov AV, Spiegel FW, Taylor MF (2005). "The new higher level classification of eukaryotes with emphasis on the taxonomy of protists". The Journal of Eukaryotic Microbiology. 52 (5): 399–451. doi:10.1111/j.1550-7408.2005.00053.x. PMID 16248873. S2CID 8060916.
  159. ^ Margulis L, Chapman MJ (19 March 2009). Kingdoms and Domains: An Illustrated Guide to the Phyla of Life on Earth. Academic Press. ISBN 9780080920146.
  160. ^ Janet Fang (6 April 2010). "Animals thrive without oxygen at sea bottom". Nature. 464 (7290): 825. doi:10.1038/464825b. PMID 20376121.
  161. ^ "Briny deep basin may be home to animals thriving without oxygen". Science News. 23 September 2013.
  162. ^ Hyde, K.D.; E.B.J. Jones; E. Leaño; S.B. Pointing; A.D. Poonyth; L.L.P. Vrijmoed (1998). "Role of fungi in marine ecosystems". Biodiversity and Conservation. 7 (9): 1147–1161. doi:10.1023/A:1008823515157. S2CID 22264931.
  163. ^ Kirk, P.M., Cannon, P.F., Minter, D.W. and Stalpers, J. "Dictionary of the Fungi". Edn 10. CABI, 2008
  164. ^ Hyde, K.D.; E.B.J. Jones (1989). "Spore attachment in marine fungi". Botanica Marina. 32 (3): 205–218. doi:10.1515/botm.1989.32.3.205. S2CID 84879817.
  165. ^ Le Calvez T, Burgaud G, Mahé S, Barbier G, Vandenkoornhuyse P (October 2009). "Fungal diversity in deep-sea hydrothermal ecosystems". Applied and Environmental Microbiology. 75 (20): 6415–21. doi:10.1128/AEM.00653-09. PMC 2765129. PMID 19633124.
  166. ^ San-Martín, A.; S. Orejanera; C. Gallardo; M. Silva; J. Becerra; R. Reinoso; M.C. Chamy; K. Vergara; J. Rovirosa (2008). "Steroids from the marine fungus Geotrichum sp". Journal of the Chilean Chemical Society. 53 (1): 1377–1378. doi:10.4067/S0717-97072008000100011.
  167. ^ Jones, E.B.G., Hyde, K.D., & Pang, K.-L., eds. (2014). Freshwater fungi: and fungal-like organisms. Berlin/Boston: De Gruyter.
  168. ^ Jones, E.B.G.; Pang, K.-L., eds. (2012). Marine Fungi, and Fungal-like Organisms. Marine and Freshwater Botany. Berlin, Boston: De Gruyter (published August 2012). doi:10.1515/9783110264067. ISBN 978-3-11-026406-7. Retrieved 3 September 2015.
  169. ^ Wang, Xin; Singh, Purnima; Gao, Zheng; Zhang, Xiaobo; Johnson, Zackary I.; Wang, Guangyi (2014). "Distribution and Diversity of Planktonic Fungi in the West Pacific Warm Pool". PLOS ONE. 9 (7): e101523. Bibcode:2014PLoSO...9j1523W. doi:10.1371/journal.pone.0101523.s001. PMC 4081592. PMID 24992154.
  170. ^ Wang, G.; Wang, X.; Liu, X.; Li, Q. (2012). "Diversity and biogeochemical function of planktonic fungi in the ocean". In Raghukumar, C. (ed.). Biology of marine fungi. Berlin, Heidelberg: Springer-Verlag. pp. 71–88. doi:10.1007/978-3-642-23342-5. ISBN 978-3-642-23341-8. S2CID 39378040. Retrieved 3 September 2015.
  171. ^ Damare, Samir; Raghukumar, Chandralata (11 November 2007). "Fungi and Macroaggregation in Deep-Sea Sediments". Microbial Ecology. 56 (1): 168–177. doi:10.1007/s00248-007-9334-y. ISSN 0095-3628. PMID 17994287. S2CID 21288251.
  172. ^ Kubanek, Julia; Jensen, Paul R.; Keifer, Paul A.; Sullards, M. Cameron; Collins, Dwight O.; Fenical, William (10 June 2003). "Seaweed resistance to microbial attack: A targeted chemical defense against marine fungi". Proceedings of the National Academy of Sciences. 100 (12): 6916–6921. Bibcode:2003PNAS..100.6916K. doi:10.1073/pnas.1131855100. ISSN 0027-8424. PMC 165804. PMID 12756301.
  173. ^ a b Gao, Zheng; Johnson, Zackary I.; Wang, Guangyi (30 July 2009). "Molecular characterization of the spatial diversity and novel lineages of mycoplankton in Hawaiian coastal waters". The ISME Journal. 4 (1): 111–120. doi:10.1038/ismej.2009.87. ISSN 1751-7362. PMID 19641535.
  174. ^ Panzer, Katrin; Yilmaz, Pelin; Weiß, Michael; Reich, Lothar; Richter, Michael; Wiese, Jutta; Schmaljohann, Rolf; Labes, Antje; Imhoff, Johannes F. (30 July 2015). "Identification of Habitat-Specific Biomes of Aquatic Fungal Communities Using a Comprehensive Nearly Full-Length 18S rRNA Dataset Enriched with Contextual Data". PLOS ONE. 10 (7): e0134377. Bibcode:2015PLoSO..1034377P. doi:10.1371/journal.pone.0134377. PMC 4520555. PMID 26226014.
  175. ^ Gutierrez, Marcelo H; Pantoja, Silvio; Quinones, Renato a and Gonzalez, Rodrigo R. First record of flamentous fungi in the coastal upwelling ecosystem off central Chile. Gayana (Concepc.) [online]. 2010, vol.74, n.1, pp. 66-73. ISSN 0717-6538.
  176. ^ a b Sridhar, K.R. (2009). "10. Aquatic fungi – Are they planktonic?". Plankton Dynamics of Indian Waters. Jaipur, India: Pratiksha Publications. pp. 133–148.
  177. ^ Species of Higher Marine Fungi Archived 22 April 2013 at the Wayback Machine University of Mississippi. Retrieved 2012-02-05.
  178. ^ Freshwater and marine lichen-forming fungi Retrieved 2012-02-06.
  179. ^ "Lichens". National Park Service, US Department of the Interior, Government of the United States. 22 May 2016. Retrieved 4 April 2018.
  180. ^ a b "The Earth Life Web, Growth and Development in Lichens". earthlife.net.
  181. ^ Silliman B. R. & S. Y. Newell (2003). "Fungal farming in a snail". PNAS. 100 (26): 15643–15648. Bibcode:2003PNAS..10015643S. doi:10.1073/pnas.2535227100. PMC 307621. PMID 14657360.
  182. ^ Yuan X, Xiao S (2005). "Lichen-Like Symbiosis 600 Million Years Ago". Science. 308 (5724): 1017–1020. Bibcode:2005Sci...308.1017Y. doi:10.1126/science.1111347. PMID 15890881. S2CID 27083645.
  183. ^ Jones, E. B. Gareth; Pang, Ka-Lai (31 August 2012). Marine Fungi: and Fungal-like Organisms. Walter de Gruyter. ISBN 9783110264067.
  184. ^ Davidson, Michael W. (26 May 2005). "Animal Cell Structure". Molecular Expressions. Tallahassee, Fla.: Florida State University. Retrieved 3 September 2008.
  185. ^ Vogel, Gretchen (20 September 2018). "This fossil is one of the world's earliest animals, according to fat molecules preserved for a half-billion years". Science. AAAS. Retrieved 21 September 2018.
  186. ^ Bobrovskiy, Ilya (2018). "Ancient steroids establish the Ediacaran fossil Dickinsonia as one of the earliest animals". Science. 361 (6408): 1246–1249. Bibcode:2018Sci...361.1246B. doi:10.1126/science.aat7228. PMID 30237355.
  187. ^ Retallack, G.J. (2007). "Growth, decay and burial compaction of Dickinsonia, an iconic Ediacaran fossil" (PDF). Alcheringa: An Australasian Journal of Palaeontology. 31 (3): 215–240. doi:10.1080/03115510701484705. S2CID 17181699.
  188. ^ Sperling, Erik; Vinther, Jakob; Pisani, Davide; Peterson, Kevin (2008). "A placozoan affinity for Dickinsonia and the evolution of Late Precambrian metazoan feeding modes" (PDF). In Cusack, M; Owen, A; Clark, N (eds.). Programme with Abstracts. Palaeontological Association Annual Meeting. 52. Glasgow, UK. p. 81.
  189. ^ Gold, D. A.; Runnegar, B.; Gehling, J. G.; Jacobs, D. K. (2015). "Ancestral state reconstruction of ontogeny supports a bilaterian affinity for Dickinsonia". Evolution & Development. 17 (6): 315–397. doi:10.1111/ede.12168. PMID 26492825. S2CID 26099557.
  190. ^ Jun-Yuan Chen; Oliveri, Paola; Feng Gao; et al. (1 August 2002). "Precambrian Animal Life: Probable Developmental and Adult Cnidarian Forms from Southwest China" (PDF). Developmental Biology. 248 (1): 182–196. doi:10.1006/dbio.2002.0714. ISSN 0012-1606. PMID 12142030. Archived from the original (PDF) on 26 May 2013. Retrieved 4 February 2015.
  191. ^ Grazhdankin, Dima (June 2004). "Patterns of distribution in the Ediacaran biotas: facies versus biogeography and evolution". Paleobiology. 30 (2): 203–221. doi:10.1666/0094-8373(2004)030<0203:PODITE>2.0.CO;2. ISSN 0094-8373.
  192. ^ Seilacher, Adolf (August 1992). "Vendobionta and Psammocorallia: lost constructions of Precambrian evolution". Journal of the Geological Society. 149 (4): 607–613. Bibcode:1992JGSoc.149..607S. doi:10.1144/gsjgs.149.4.0607. ISSN 0016-7649. S2CID 128681462. Retrieved 4 February 2015.
  193. ^ Martin, Mark W.; Grazhdankin, Dmitriy V.; Bowring, Samuel A.; et al. (5 May 2000). "Age of Neoproterozoic Bilaterian Body and Trace Fossils, White Sea, Russia: Implications for Metazoan Evolution". Science. 288 (5467): 841–845. Bibcode:2000Sci...288..841M. doi:10.1126/science.288.5467.841. ISSN 0036-8075. PMID 10797002. S2CID 1019572.
  194. ^ Fedonkin, Mikhail A.; Waggoner, Benjamin M. (28 August 1997). "The late Precambrian fossil Kimberella is a mollusc-like bilaterian organism". Nature. 388 (6645): 868–871. Bibcode:1997Natur.388..868F. doi:10.1038/42242. ISSN 0028-0836. S2CID 4395089.
  195. ^ Mooi, Rich; David, Bruno (December 1998). "Evolution Within a Bizarre Phylum: Homologies of the First Echinoderms". American Zoologist. 38 (6): 965–974. doi:10.1093/icb/38.6.965. ISSN 1540-7063.
  196. ^ McMenamin, Mark A. S. (September 2003). Spriggina is a trilobitoid ecdysozoan. Geoscience Horizons Seattle 2003. Abstracts with Programs. 35. Boulder, Colo.: Geological Society of America. p. 105. OCLC 249088612. Archived from the original on 12 April 2016. Retrieved 24 November 2007. Paper No. 40-2 presented at the Geological Society of America's 2003 Seattle Annual Meeting (2–5 November 2003) on 2 November 2003, at the Washington State Convention Center.
  197. ^ Jih-Pai Lin; Gon, Samuel M., III; Gehling, James G.; et al. (2006). "A Parvancorina-like arthropod from the Cambrian of South China". Historical Biology: An International Journal of Paleobiology. 18 (1): 33–45. doi:10.1080/08912960500508689. ISSN 1029-2381. S2CID 85821717.
  198. ^ Butterfield, Nicholas J. (December 2006). "Hooking some stem-group 'worms': fossil lophotrochozoans in the Burgess Shale". BioEssays. 28 (12): 1161–1166. doi:10.1002/bies.20507. ISSN 0265-9247. PMID 17120226. S2CID 29130876.
  199. ^ a b Bengtson 2004, pp. 67–78
  200. ^ Valentine, James W. (2004). On the Origin of Phyla. Chicago: University Of Chicago Press. p. 7. ISBN 978-0-226-84548-7. Classifications of organisms in hierarchical systems were in use by the seventeenth and eighteenth centuries. Usually organisms were grouped according to their morphological similarities as perceived by those early workers, and those groups were then grouped according to their similarities, and so on, to form a hierarchy.
  201. ^ a b Valentine, James W (18 June 2004). On the Origin of Phyla. ISBN 9780226845487.
  202. ^ WoRMS Editorial Board. World Register of Marine Species. Available online: http://www.marinespecies.org at VLIZ. Accessed: 18 October 2019.
  203. ^ Novak, B.J.; Fraser, D.; Maloney, T.H. (2020). "Transforming ocean conservation: applying the genetic rescue toolkit". Genes. 11 (2): 209. doi:10.3390/genes11020209. PMC 7074136. PMID 32085502.
  204. ^ Gould, Stephen Jay (1990) Wonderful Life: The Burgess Shale and the Nature of History W. W. Norton. ISBN 9780393307009.
  205. ^ Erwin, Douglas; Valentine, James; Jablonski, David (1997). "Recent fossil finds and new insights into animal development are providing fresh perspectives on the riddle of the explosion of animals during the Early Cambrian". American Scientist (March–April).
  206. ^ a b Budd, G.E.; Jensen, S. (May 2000). "A critical reappraisal of the fossil record of the bilaterian phyla". Biological Reviews. 75 (2): 253–295. doi:10.1111/j.1469-185X.1999.tb00046.x. PMID 10881389. S2CID 39772232.
  207. ^ Gould 1989
  208. ^ Budd, Graham E. (February 2003). "The Cambrian Fossil Record and the Origin of the Phyla" (PDF). Integrative and Comparative Biology. 43 (1): 157–165. doi:10.1093/icb/43.1.157. ISSN 1557-7023. PMID 21680420.
  209. ^ Budd, Graham E. (March 1996). "The morphology of Opabinia regalis and the reconstruction of the arthropod stem-group". Lethaia. 29 (1): 1–14. doi:10.1111/j.1502-3931.1996.tb01831.x. ISSN 0024-1164.
  210. ^ Marshall, Charles R. (May 2006). "Explaining the Cambrian 'Explosion' of Animals". Annual Review of Earth and Planetary Sciences. 34: 355–384. Bibcode:2006AREPS..34..355M. doi:10.1146/annurev.earth.33.031504.103001. ISSN 1545-4495. S2CID 85623607.
  211. ^ King, N.; Rokas, A. (2017). "Embracing uncertainty in reconstructing early animal evolution". Current Biology. 27 (19): R1081–R1088. doi:10.1016/j.cub.2017.08.054. PMC 5679448. PMID 29017048.
  212. ^ Feuda, R.; Dohrmann, M.; Pett, W.; Philippe, H.; Rota-Stabelli, O.; Lartillot, N.; Wörheide, G.; Pisani, D. (2017). "Improved modeling of compositional heterogeneity supports sponges as sister to all other animals". Current Biology. 27 (24): 3864–3870. doi:10.1016/j.cub.2017.11.008. PMID 29199080.
  213. ^ Nielsen, Claus (2019). ""Early animal evolution: a morphologist's view", review article". Royal Society Open Science. 6 (7): 7. doi:10.1098/rsos.190638. PMC 6689584. PMID 31417759.
  214. ^ Porifera (n.) Online Etymology Dictionary. Retrieved 18 August 2016.
  215. ^ a b Petralia, R.S.; Mattson, M.P.; Yao, P.J. (2014). "Aging and longevity in the simplest animals and the quest for immortality". Ageing Research Reviews. 16: 66–82. doi:10.1016/j.arr.2014.05.003. PMC 4133289. PMID 24910306.
  216. ^ Jochum, K.P.; Wang, X.; Vennemann, T.W.; Sinha, B.; Müller, W.E. (2012). "Siliceous deep-sea sponge Monorhaphis chuni: A potential paleoclimate archive in ancient animals". Chemical Geology. 300: 143–151. Bibcode:2012ChGeo.300..143J. doi:10.1016/j.chemgeo.2012.01.009.
  217. ^ Vacelet & Duport 2004, pp. 179–190.
  218. ^ "Spongia Linnaeus, 1759". World Register of Marine Species. Retrieved 18 July 2012.
  219. ^ Rowland, S. M. & Stephens, T. (2001). "Archaeocyatha: A history of phylogenetic interpretation". Journal of Paleontology. 75 (6): 1065–1078. doi:10.1666/0022-3360(2001)075<1065:AAHOPI>2.0.CO;2. JSTOR 1307076.
  220. ^ Sperling, E. A.; Pisani, D.; Peterson, K. J. (1 January 2007). "Poriferan paraphyly and its implications for Precambrian palaeobiology" (PDF). Geological Society, London, Special Publications. 286 (1): 355–368. Bibcode:2007GSLSP.286..355S. doi:10.1144/SP286.25. S2CID 34175521. Archived from the original (PDF) on 20 December 2009. Retrieved 22 August 2012.
  221. ^ Ruppert, E.E.; Fox, R.S. & Barnes, R.D. (2004). Invertebrate Zoology (7 ed.). Brooks / Cole. pp. 182–195. ISBN 978-0-03-025982-1.
  222. ^ Mills, C.E. "Ctenophores – some notes from an expert". Retrieved 5 February 2009.
  223. ^ a b Brusca R. C. and Brusca G. J. (2003) Invertebrates, Second Edition, Sinauer Associates. ISBN 9780878930975.
  224. ^ Michael Le Page (March 2019). "Animal with an anus that comes and goes could reveal how ours evolved". New Scientist.
  225. ^ Martindale, Mark; Finnerty, J.R.; Henry, J.Q. (September 2002). "The Radiata and the evolutionary origins of the bilaterian body plan". Molecular Phylogenetics and Evolution. 24 (3): 358–365. doi:10.1016/s1055-7903(02)00208-7. PMID 12220977.
  226. ^ Placozoa at the US National Library of Medicine Medical Subject Headings (MeSH)
  227. ^ Rüdiger Wehner & Walter Gehring (June 2007). Zoologie (in German) (24th ed.). Stuttgart: Thieme. p. 696.
  228. ^ F. E. Schulze "Trichoplax adhaerens n. g., n. s.", Zoologischer Anzeiger (Elsevier, Amsterdam and Jena) 6 (1883), p. 92.
  229. ^ Eitel, Michael; Francis, Warren; Osigus, Hans-Jürgen; Krebs, Stefan; Vargas, Sergio; Blum, Helmut; Williams, Gray Argust; Schierwater, Bernd; Wörheide, Gert (13 October 2017). "A taxogenomics approach uncovers a new genus in the phylum Placozoa". bioRxiv: 202119. doi:10.1101/202119. S2CID 89829846.
  230. ^ Schierwater, Bernd; Kamm, Kai; Herzog, Rebecca; Rolfes, Sarah; Osigus, Hans-Jürgen (4 March 2019). "Polyplacotoma mediterranea is a new ramified placozoan species". Current Biology. 29 (5): R148–R149. doi:10.1016/j.cub.2019.01.068. ISSN 0960-9822. PMID 30836080.
  231. ^ Trichoplax adhaerens, WoRMS, 2009.
  232. ^ Smith, Carolyn L.; Varoqueaux, Frédérique; Kittelmann, Maike; Azzam, Rita N.; Cooper, Benjamin; Winters, Christine A.; Eitel, Michael; Fasshauer, Dirk; Reese, Thomas S. (2014). "Novel Cell Types, Neurosecretory Cells, and Body Plan of the Early-Diverging Metazoan Trichoplax adhaerens". Current Biology. 24 (14): 1565–1572. doi:10.1016/j.cub.2014.05.046. ISSN 0960-9822. PMC 4128346. PMID 24954051.
  233. ^ Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia: Holt-Saunders International. pp. 84–85. ISBN 978-0-03-056747-6.
  234. ^ Zhang, Z.-Q. (2011). "Animal biodiversity: An introduction to higher-level classification and taxonomic richness" (PDF). Zootaxa. 3148: 7–12. doi:10.11646/zootaxa.3148.1.3.
  235. ^ "Nematostella vectensis v1.0". Genome Portal. University of California. Retrieved 19 January 2014.
  236. ^ "Nematostella". Nematostella.org. Archived from the original on 8 May 2006. Retrieved 18 January 2014.
  237. ^ a b Genikhovich, G. & U. Technau (2009). "The Starlet sea anemone Nematostella vectensis: An anthozoan model organism for studies in comparative genomics and functional evolutionary developmental biology". Cold Spring Harbor Protocols. 2009 (9): pdb.emo129. doi:10.1101/pdb.emo129. PMID 20147257.
  238. ^ "Where Does Our Head Come From? Brainless Sea Anemone Sheds New Light on the Evolutionary Origin of the Head". Science Daily. 12 February 2013. Retrieved 18 January 2014.
  239. ^ Sinigaglia, C.; et al. (2013). "The bilaterian head patterning gene six3/6 controls aboral domain development in a cnidarian". PLOS Biology. 11 (2): e1001488. doi:10.1371/journal.pbio.1001488. PMC 3586664. PMID 23483856.
  240. ^ "Red Paper Lantern Jellyfish". Real Monstrosities. Retrieved 25 October 2015.
  241. ^ "Blue Buttons in Florida."
  242. ^ Karleskint G, Richard Turner R and, James Small J (2012) Introduction to Marine Biology Cengage Learning, edition 4, page 445. ISBN 9781133364467.
  243. ^ Bavestrello, Giorgio; Christian Sommer; Michele Sarà (1992). "Bi-directional conversion in Turritopsis nutricula (Hydrozoa)". Scientia Marina. 56 (2–3): 137–140.
  244. ^ Piraino, Stefano; F. Boero; B. Aeschbach; V. Schmid (1996). "Reversing the life cycle: medusae transforming into polyps and cell transdifferentiation in Turritopsis nutricula (Cnidaria, Hydrozoa)". Biological Bulletin. 190 (3): 302–312. doi:10.2307/1543022. JSTOR 1543022. PMID 29227703. S2CID 3956265.
  245. ^ Fenner PJ, Williamson JA (1996). "Worldwide deaths and severe envenomation from jellyfish stings". The Medical Journal of Australia. 165 (11–12): 658–61. doi:10.5694/j.1326-5377.1996.tb138679.x. PMID 8985452. S2CID 45032896.
  246. ^ a b Cannon, Johanna Taylor; Vellutini, Bruno Cossermelli; Smith, Julian; Ronquist, Fredrik; Jondelius, Ulf; Hejnol, Andreas (2016). "Xenacoelomorpha is the sister group to Nephrozoa". Nature. 530 (7588): 89–93. Bibcode:2016Natur.530...89C. doi:10.1038/nature16520. PMID 26842059. S2CID 205247296.
  247. ^ a b Minelli, Alessandro (2009). Perspectives in Animal Phylogeny and Evolution. Oxford University Press. p. 53. ISBN 978-0-19-856620-5.
  248. ^ a b c Brusca, Richard C. (2016). Introduction to the Bilateria and the Phylum Xenacoelomorpha | Triploblasty and Bilateral Symmetry Provide New Avenues for Animal Radiation (PDF). Invertebrates. Sinauer Associates. pp. 345–372. ISBN 978-1605353753.
  249. ^ Finnerty, John R. (November 2005). "Did internal transport, rather than directed locomotion, favor the evolution of bilateral symmetry in animals?" (PDF). BioEssays. 27 (11): 1174–1180. doi:10.1002/bies.20299. PMID 16237677. Archived from the original (PDF) on 10 August 2014. Retrieved 27 August 2019.
  250. ^ Quillin, K. J. (May 1998). "Ontogenetic scaling of hydrostatic skeletons: geometric, static stress and dynamic stress scaling of the earthworm lumbricus terrestris". The Journal of Experimental Biology. 201 (12): 1871–83. doi:10.1242/jeb.201.12.1871. PMID 9600869.
  251. ^ This primeval worm may be the ancestor of all animals Live Science, 26 March 2020.
  252. ^ Cannon, J.T.; Vellutini, B.C.; Smith, J.; Ronquist, F.; Jondelius, U.; Hejnol, A. (2016). "Xenacoelomorpha is the sister group to Nephrozoa". Nature. 530 (7588): 89–93. Bibcode:2016Natur.530...89C. doi:10.1038/nature16520. PMID 26842059. S2CID 205247296.
  253. ^ a b Wade, Nicholas (30 January 2017). "This Prehistoric Human Ancestor Was All Mouth". The New York Times. Retrieved 31 January 2017.
  254. ^ a b Han, Jian; Morris, Simon Conway; Ou, Qiang; Shu, Degan; Huang, Hai (2017). "Meiofaunal deuterostomes from the basal Cambrian of Shaanxi (China)". Nature. 542 (7640): 228–231. Bibcode:2017Natur.542..228H. doi:10.1038/nature21072. ISSN 0028-0836. PMID 28135722. S2CID 353780.
  255. ^ "Cornwall – Nature – Superstar Worm". BBC.
  256. ^ Mark Carwardine (1995) The Guinness Book of Animal Records. Guinness Publishing. p. 232.
  257. ^ "The Persistent Parasites". Time. 8 April 1957.
  258. ^ Hargis, William J. (1985). "Parasitology and pathology of marine organisms of the world ocean". National Oceanic and Atmospheric Administration. Cite journal requires |journal= (help)
  259. ^ http://plpnemweb.ucdavis.edu/nemaplex/General/animpara.htm
  260. ^ Lynne S. Garcia (1999). "Classification of Human Parasites, Vectors, and Similar Organisms". Clin Infect Dis. 29 (4): 734–6. doi:10.1086/520425. PMID 10589879.
  261. ^ Hodda, M (2011). "Phylum Nematoda Cobb, 1932. In: Zhang, Z.-Q. Animal biodiversity: An outline of higher-level classification and survey of taxonomic richness". Zootaxa. 3148: 63–95. doi:10.11646/zootaxa.3148.1.11.
  262. ^ Zhang, Z (2013). "Animal biodiversity: An update of classification and diversity in 2013. In: Zhang, Z.-Q. (Ed.) Animal Biodiversity: An Outline of Higher-level Classification and Survey of Taxonomic Richness (Addenda 2013)". Zootaxa. 3703 (1): 5–11. doi:10.11646/zootaxa.3703.1.3. S2CID 85252974.
  263. ^ Lambshead PJD (1993). "Recent developments in marine benthic biodiversity research". Oceanis. 19 (6): 5–24.
  264. ^ Borgonie G, García-Moyano A, Litthauer D, Bert W, Bester A, van Heerden E, Möller C, Erasmus M, Onstott TC (June 2011). "Nematoda from the terrestrial deep subsurface of South Africa". Nature. 474 (7349): 79–82. Bibcode:2011Natur.474...79B. doi:10.1038/nature09974. hdl:1854/LU-1269676. PMID 21637257. S2CID 4399763.
  265. ^ Danovaro R, Gambi C, Dell'Anno A, Corinaldesi C, Fraschetti S, Vanreusel A, Vincx M, Gooday AJ (January 2008). "Exponential decline of deep-sea ecosystem functioning linked to benthic biodiversity loss". Current Biology. 18 (1): 1–8. doi:10.1016/j.cub.2007.11.056. PMID 18164201. S2CID 15272791. Lay summary – EurekAlert!.
  266. ^ Platt HM (1994). "foreword". In Lorenzen S, Lorenzen SA (eds.). The phylogenetic systematics of freeliving nematodes. London: The Ray Society. ISBN 978-0-903874-22-9.
  267. ^ Barnes, R.S.K.; Calow, P.; Olive, P.J.W.; Golding, D.W. & Spicer, J.I. (2001). The Invertebrates, A Synthesis (3rd ed.). UK: Blackwell Science.
  268. ^ Tyrian Purple Green Lion, 28 February 2014.
  269. ^ Chapman, A.D. (2009). Numbers of Living Species in Australia and the World, 2nd edition. Australian Biological Resources Study, Canberra. Retrieved 12 January 2010. ISBN 978-0-642-56860-1 (printed); ISBN 978-0-642-56861-8 (online).
  270. ^ Hancock, Rebecca (2008). "Recognising research on molluscs". Australian Museum. Archived from the original on 30 May 2009. Retrieved 9 March 2009.
  271. ^ Ponder, W.F.; Lindberg, D.R., eds. (2008). Phylogeny and Evolution of the Mollusca. Berkeley: University of California Press. p. 481. ISBN 978-0-520-25092-5.
  272. ^ Munro, D.; Blier, P.U. (2012). "The extreme longevity of Arctica islandica is associated with increased peroxidation resistance in mitochondrial membranes". Aging Cell. 11 (5): 845–55. doi:10.1111/j.1474-9726.2012.00847.x. PMID 22708840. S2CID 205634828.
  273. ^ "Welcome to CephBase". CephBase. Retrieved 29 January 2016.
  274. ^ Wilbur, Karl M.; Clarke, M.R.; Trueman, E.R., eds. (1985), The Mollusca, 12. Paleontology and neontology of Cephalopods, New York: Academic Press, ISBN 0-12-728702-7
  275. ^ "Are there any freshwater cephalopods?". 16 January 2013.
  276. ^ Ewen Callaway (2 June 2008). "Simple-Minded Nautilus Shows Flash of Memory". New Scientist. Retrieved 7 March 2012.
  277. ^ Kathryn Phillips (15 June 2008). "Living Fossil Memories". Journal of Experimental Biology. 211 (12): iii. doi:10.1242/jeb.020370. S2CID 84279320.
  278. ^ Robyn Crook & Jennifer Basil (2008). "A biphasic memory curve in the chambered nautilus, Nautilus pompilius L. (Cephalopoda: Nautiloidea)". Journal of Experimental Biology. 211 (12): 1992–1998. doi:10.1242/jeb.018531. PMID 18515730. S2CID 6305526.
  279. ^ Black, Richard (26 April 2008). "Colossal squid out of the freezer". BBC News.
  280. ^ Ruppert, Edward E.; Fox, Richard, S.; Barnes, Robert D. (2004). Invertebrate Zoology (7th ed.). Cengage Learning. ISBN 978-81-315-0104-7.
  281. ^ Hayward, PJ (1996). Handbook of the Marine Fauna of North-West Europe. Oxford University Press. ISBN 978-0-19-854055-7.
  282. ^ Ruppert, Fox & Barnes (2004), pp. 518–522
  283. ^ Wilson, Heather M.; Anderson, Lyall I. (January 2004). "Morphology and taxonomy of Paleozoic millipedes (Diplopoda: Chilognatha: Archipolypoda) from Scotland". Journal of Paleontology. 78 (1): 169–184. doi:10.1666/0022-3360(2004)078<0169:MATOPM>2.0.CO;2.
  284. ^ Stephanie E. Suarez; Michael E. Brookfield; Elizabeth J. Catlos; Daniel F. Stöckli (2017). "A U-Pb zircon age constraint on the oldest-recorded air-breathing land animal". PLOS ONE. 12 (6): e0179262. Bibcode:2017PLoSO..1279262S. doi:10.1371/journal.pone.0179262. PMC 5489152. PMID 28658320.
  285. ^ Campbell, L.I.; Rota-Stabelli, O.; Edgecombe, G.D.; Marchioro, T.; Longhorn, S.J.; Telford, M.J.; Philippe, H.; Rebecchi, L.; Peterson, K.J.; Pisani, D. (2011). "MicroRNAs and phylogenomics resolve the relationships of Tardigrada and suggest that velvet worms are the sister group of Arthropoda". Proceedings of the National Academy of Sciences. 108 (38): 15920–15924. Bibcode:2011PNAS..10815920C. doi:10.1073/pnas.1105499108. PMC 3179045. PMID 21896763.
  286. ^ Smith, F.W.; Goldstein, B. (2017). "Segmentation in Tardigrada and diversification of segmental patterns in Panarthropoda". Arthropod Structure & Development. 46 (3): 328–340. doi:10.1016/j.asd.2016.10.005. PMID 27725256.
  287. ^ Budd, G. E. (2001). "Why are arthropods segmented?". Evolution and Development. 3 (5): 332–42. doi:10.1046/j.1525-142X.2001.01041.x. PMID 11710765. S2CID 37935884.
  288. ^ "Archived copy". Archived from the original on 26 January 2011. Retrieved 10 March 2011.CS1 maint: archived copy as title (link)
  289. ^ Braddy, Simon J.; Poschmann, Markus; Tetlie, O. Erik (2007). "Giant claw reveals the largest ever arthropod". Biology Letters. 4 (1): 106–109. doi:10.1098/rsbl.2007.0491. PMC 2412931. PMID 18029297.
  290. ^ Cressey, Daniel (21 November 2007). "Giant sea scorpion discovered". Nature. doi:10.1038/news.2007.272. Retrieved 10 June 2013.
  291. ^ "An ugly giant crab of Japan". Popular Science. 96 (6): 42. 1920.
  292. ^ D. R. Currie & T. M. Ward (2009). South Australian Giant Crab (Pseudocarcinus gigas) Fishery (PDF). South Australian Research and Development Institute. Fishery Assessment Report for PIRSA. Archived from the original (PDF) on 28 March 2012. Retrieved 9 December 2013.
  293. ^ Patrick Kilday (28 September 2005). "Mantis shrimp boasts most advanced eyes". The Daily Californian.
  294. ^ S. N. Patek & R. L. Caldwell (2005). "Extreme impact and cavitation forces of a biological hammer: strike forces of the peacock mantis shrimp". Journal of Experimental Biology. 208 (19): 3655–3664. doi:10.1242/jeb.01831. PMID 16169943. S2CID 312009.
  295. ^ Ghosh, Pallab (30 January 2017). "Scientists find 'oldest human ancestor'". BBC. Retrieved 30 January 2017.
  296. ^ "Animal Diversity Web - Echinodermata". University of Michigan Museum of Zoology. Retrieved 26 August 2012.
  297. ^ "Sea Lily". Science Encyclopedia. Retrieved 5 September 2014.
  298. ^ Fox, Richard. "Asterias forbesi". Invertebrate Anatomy OnLine. Lander University. Retrieved 14 June 2014.
  299. ^ Holsinger, K. (2005). Keystone species. Retrieved 10 May 2010, from "Archived copy". Archived from the original on 30 June 2010. Retrieved 12 May 2010.CS1 maint: archived copy as title (link)
  300. ^ Simakov, O.; Kawashima, T.; Marlétaz, F.; Jenkins, J.; Koyanagi, R.; Mitros, T.; Hisata, K.; Bredeson, J.; Shoguchi, E.; Gyoja, F.; Yue, J.X. (2015). "Hemichordate genomes and deuterostome origins". Nature. 527 (7579): 459–65. Bibcode:2015Natur.527..459S. doi:10.1038/nature16150. PMC 4729200. PMID 26580012.
  301. ^ How humans got a pharynx from this 'ugly beast', Futurity, 23 November 2015.
  302. ^ a b c d Clark, M.A., Choi, J. and Douglas, M. (2018) Chordates Biology 2e. OpenStax. ISBN 9781947172951. Material was copied from this source, which is available under a Creative Commons Attribution 4.0 International License
  303. ^ The secret to an Oesia life: Prehistoric worm built tube-like 'houses' on sea floor
  304. ^ Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. pp. 1018–1026. ISBN 978-0-03-056747-6.
  305. ^ Secondary organizers of the early brain and the location of the meso-diencephalic dopaminergic precursor cells Archived 10 March 2014 at the Wayback Machine Retrieved March 10, 2014
  306. ^ Rob Mitchum (15 March 2012). "The Secret Origin of the Vertebrate Brain". Nature. ScienceLife. 483 (7389): 289–94. doi:10.1038/nature10838. PMC 3719855. PMID 22422262. Retrieved 18 February 2014.
  307. ^ Chordates OpenStax, 9 May 2019.
  308. ^ Gewin, V (2005). "Functional genomics thickens the biological plot". PLOS Biology. 3 (6): e219. doi:10.1371/journal.pbio.0030219. PMC 1149496. PMID 15941356.
  309. ^ Lancelet (amphioxus) genome and the origin of vertebrates Ars Technica, 19 June 2008.
  310. ^ Lemaire, P (2011). "Evolutionary crossroads in developmental biology: the tunicates". Development. 138 (11): 2143–2152. doi:10.1242/dev.048975. PMID 21558365. S2CID 40452112.
  311. ^ "FishBase: A Global Information System on Fishes". FishBase. Retrieved 17 January 2017.
  312. ^ "How Many Fish In The Sea? Census Of Marine Life Launches First Report". Science Daily. Retrieved 17 January 2017.
  313. ^ Docker, Margaret F. (2006) "Bill Beamish's Contributions to Lamprey Research and Recent Advances in the Field", Guelph Ichthyology Reviews, 7.
  314. ^ Hardisty, M. W.; Potter, I. C. (1971). Hardisty, M. W.; Potter, I. C. (eds.). The Biology of Lampreys (1st ed.). Academic Press. ISBN 978-0-123-24801-5.
  315. ^ Gill, Howard S.; Renaud, Claude B.; Chapleau, François; Mayden, Richard L.; Potter, Ian C.; Douglas, M. E. (2003). "Phylogeny of Living Parasitic Lampreys (Petromyzontiformes) Based on Morphological Data". Copeia. 2003 (4): 687–703. doi:10.1643/IA02-085.1. S2CID 85969032.
  316. ^ "Myxini". University of California Museum of Paleontology. Archived from the original on 15 December 2017. Retrieved 17 January 2017.
  317. ^ Greena, Stephen A.; Bronner, Marianne E. (2014). "The Lamprey: A jawless vertebrate model system for examining origin of the neural crest and other vertebrate traits". Differentiation. 87 (1–2): 44–51. doi:10.1016/j.diff.2014.02.001. PMC 3995830. PMID 24560767.
  318. ^ Stock, D.; Whitt, G.S. (7 August 1992). "Evidence from 18S ribosomal RNA sequences that lampreys and hagfish form a natural group". Science. 257 (5071): 787–9. Bibcode:1992Sci...257..787S. doi:10.1126/science.1496398. PMID 1496398.
  319. ^ Nicholls, H. (10 September 2009). "Mouth to Mouth". Nature. 461 (7261): 164–166. doi:10.1038/461164a. PMID 19741680.
  320. ^ McCoy, Victoria E.; Saupe, Erin E.; Lamsdell, James C.; et al. (28 April 2016). "The 'Tully monster' is a vertebrate". Nature. 532 (7600): 496–499. Bibcode:2016Natur.532..496M. doi:10.1038/nature16992. PMID 26982721. S2CID 205247805.
  321. ^ Sallan, L.; Giles, S.; Sansom, R. S.; et al. (20 February 2017). "The 'Tully Monster' is not a vertebrate: characters, convergence and taphonomy in Palaeozoic problematic animals" (PDF). Palaeontology. 60 (2): 149–157. doi:10.1111/pala.12282.
  322. ^ Ancient 'Tully monster' was a vertebrate, not a spineless blob, study claims Live Science, 4 May 2020.
  323. ^ McCoy, V.E.; Wiemann, J.; Lamsdell, J.C.; Whalen, C.D.; Lidgard, S.; Mayer, P.; Petermann, H.; Briggs, D.E. (2020). "Chemical signatures of soft tissues distinguish between vertebrates and invertebrates from the Carboniferous Mazon Creek Lagerstätte of Illinois". Geobiology. 18 (5): 560–565. doi:10.1111/gbi.12397. PMID 32347003.
  324. ^ Kimmel, C. B.; Miller, C. T.; Keynes, R. J. (2001). "Neural crest patterning and the evolution of the jaw". Journal of Anatomy. 199 (1&2): 105–119. doi:10.1017/S0021878201008068. PMC 1594948. PMID 11523812.
  325. ^ Gai, Z.; Zhu, M. (2012). "The origin of the vertebrate jaw: Intersection between developmental biology-based model and fossil evidence". Chinese Science Bulletin. 57 (30): 3819–3828. Bibcode:2012ChSBu..57.3819G. doi:10.1007/s11434-012-5372-z.
  326. ^ Maisey, J. G. (2000). Discovering Fossil Fishes. Westview Press. pp. 1–223. ISBN 978-0-8133-3807-1.
  327. ^ a b Wroe, S.; Huber, D. R.; Lowry, M.; McHenry, C.; Moreno, K.; Clausen, P.; Ferrara, T. L.; Cunningham, E.; Dean, M. N.; Summers, A. P. (2008). "Three-dimensional computer analysis of white shark jaw mechanics: how hard can a great white bite?" (PDF). Journal of Zoology. 276 (4): 336–342. doi:10.1111/j.1469-7998.2008.00494.x.
  328. ^ Pimiento, Catalina; Dana J. Ehret; Bruce J. MacFadden; Gordon Hubbell (10 May 2010). Stepanova, Anna (ed.). "Ancient Nursery Area for the Extinct Giant Shark Megalodon from the Miocene of Panama". PLOS ONE. 5 (5): e10552. Bibcode:2010PLoSO...510552P. doi:10.1371/journal.pone.0010552. PMC 2866656. PMID 20479893.
  329. ^ Lambert, Olivier; Bianucci, Giovanni; Post, Klaas; de Muizon, Christian; Salas-Gismondi, Rodolfo; Urbina, Mario; Reumer, Jelle (1 July 2010). "The giant bite of a new raptorial sperm whale from the Miocene epoch of Peru". Nature. 466 (7302): 105–108. Bibcode:2010Natur.466..105L. doi:10.1038/nature09067. PMID 20596020. S2CID 4369352.
  330. ^ Nielsen, Julius; Hedeholm, Rasmus B.; Heinemeier, Jan; Bushnell, Peter G.; Christiansen, Jørgen S.; Olsen, Jesper; Ramsey, Christopher Bronk; Brill, Richard W.; Simon, Malene; Steffensen, Kirstine F.; Steffensen, John F. (2016). "Eye lens radiocarbon reveals centuries of longevity in the Greenland shark (Somniosus microcephalus)". Science. 353 (6300): 702–4. Bibcode:2016Sci...353..702N. doi:10.1126/science.aaf1703. PMID 27516602. S2CID 206647043. Lay summary – Sci News (12 August 2016).
  331. ^ Marshall, A.; Bennett, M.B.; Kodja, G.; Hinojosa-Alvarez, S.; Galvan-Magana, F.; Harding, M.; Stevens, G. & Kashiwagi, T. (2011). "Manta birostris". IUCN Red List of Threatened Species. 2011: e.T198921A9108067. doi:10.2305/IUCN.UK.2011-2.RLTS.T198921A9108067.en.
  332. ^ Black, Richard (11 June 2007). "Sawfish protection acquires teeth". BBC News.
  333. ^ Thomas J. Near; et al. (2012). "Resolution of ray-finned fish phylogeny and timing of diversification". PNAS. 109 (34): 13698–13703. Bibcode:2012PNAS..10913698N. doi:10.1073/pnas.1206625109. PMC 3427055. PMID 22869754.
  334. ^ a b Zhu, M; Zhao, W; Jia, L; Lu, J; Qiao, T; Qu, Q (2009). "The oldest articulated osteichthyan reveals mosaic gnathostome characters". Nature. 458 (7237): 469–474. Bibcode:2009Natur.458..469Z. doi:10.1038/nature07855. PMID 19325627. S2CID 669711.
  335. ^ Clack, J. A. (2002) Gaining Ground. Indiana University
  336. ^ "Chondrosteans: Sturgeon Relatives". paleos.com. Archived from the original on 25 December 2010.
  337. ^ López-Arbarello, A (2012). "Phylogenetic Interrelationships of Ginglymodian Fishes (Actinopterygii: Neopterygii)". PLOS ONE. 7 (7): e39370. Bibcode:2012PLoSO...739370L. doi:10.1371/journal.pone.0039370. PMC 3394768. PMID 22808031.
  338. ^ Berra, Tim M. (2008). Freshwater Fish Distribution. University of Chicago Press. p. 55. ISBN 978-0-226-04443-9.
  339. ^ Lackmann, Alec R.; Andrews, Allen H.; Butler, Malcolm G.; Bielak-Lackmann, Ewelina S.; Clark, Mark E. (23 May 2019). "Bigmouth Buffalo Ictiobus cyprinellus sets freshwater teleost record as improved age analysis reveals centenarian longevity". Communications Biology. 2 (1): 197. doi:10.1038/s42003-019-0452-0. ISSN 2399-3642. PMC 6533251. PMID 31149641.
  340. ^ a b Benton, Michael (2005). "The Evolution of Fishes After the Devonian". Vertebrate Palaeontology (3rd ed.). John Wiley & Sons. pp. 175–84. ISBN 978-1-4051-4449-0.
  341. ^ Bone, Q.; Moore, R. (2008). Biology of Fishes. Garland Science. p. 29. ISBN 978-0-415-37562-7.
  342. ^ Dorit, R. L.; Walker, W. F.; Barnes, R. D. (1991). Zoology. Saunders College Publishing. pp. 67–69. ISBN 978-0-03-030504-7.
  343. ^ "Scientists Describe the World's Smallest, Lightest Fish". Scripps Institution of Oceanography. 20 July 2004. Retrieved 9 April 2016.
  344. ^ Roach, John (13 May 2003). "World's Heaviest Bony Fish Discovered?". National Geographic News. Retrieved 9 January 2016.
  345. ^ The World Conservation Union. 2014. IUCN Red List of Threatened Species, 2014.3. Summary Statistics for Globally Threatened Species. Table 1: Numbers of threatened species by major groups of organisms (1996–2014).
  346. ^ Narkiewicz, Katarzyna; Narkiewicz, Marek (January 2015). "The age of the oldest tetrapod tracks from Zachełmie, Poland". Lethaia. 48 (1): 10–12. doi:10.1111/let.12083. ISSN 0024-1164.
  347. ^ Long JA, Gordon MS (September–October 2004). "The greatest step in vertebrate history: a paleobiological review of the fish-tetrapod transition". Physiol. Biochem. Zool. 77 (5): 700–19. doi:10.1086/425183. PMID 15547790. S2CID 1260442. as PDF
  348. ^ Shubin, N. (2008). Your Inner Fish: A Journey Into the 3.5-Billion-Year History of the Human Body. New York: Pantheon Books. ISBN 978-0-375-42447-2.
  349. ^ Laurin, M. (2010). How Vertebrates Left the Water. Berkeley, California, USA.: University of California Press. ISBN 978-0-520-26647-6.
  350. ^ Canoville, Aurore; Laurin, Michel (2010). "Evolution of humeral microanatomy and lifestyle in amniotes, and some comments on paleobiological inferences". Biological Journal of the Linnean Society. 100 (2): 384–406. doi:10.1111/j.1095-8312.2010.01431.x.
  351. ^ Laurin, Michel; Canoville, Aurore; Quilhac, Alexandra (2009). "Use of paleontological and molecular data in supertrees for comparative studies: the example of lissamphibian femoral microanatomy". Journal of Anatomy. 215 (2): 110–123. doi:10.1111/j.1469-7580.2009.01104.x. PMC 2740958. PMID 19508493.
  352. ^ Hopkins Gareth R.; Brodie Edmund D. Jr (2015). "Occurrence of Amphibians in Saline Habitats: A Review and Evolutionary Perspective". Herpetological Monographs. 29 (1): 1–27. doi:10.1655/HERPMONOGRAPHS-D-14-00006. S2CID 83659304.
  353. ^ Natchev, Nikolay; Tzankov, Nikolay; Geme, Richard (2011). "Green frog invasion in the Black Sea: habitat ecology of the Pelophylax esculentus complex (Anura, Amphibia) population in the region of Shablenska Tuzla lagoon in Bulgaria" (PDF). Herpetology Notes. 4: 347–351.
  354. ^ Sander, P. Martin (2012). "Reproduction in early amniotes". Science. 337 (6096): 806–808. Bibcode:2012Sci...337..806S. doi:10.1126/science.1224301. PMID 22904001. S2CID 7041966.
  355. ^ Modesto, S.P.; Anderson, J.S. (2004). "The phylogenetic definition of Reptilia". Systematic Biology. 53 (5): 815–821. doi:10.1080/10635150490503026. PMID 15545258.
  356. ^ Gauthier, J.A.; Kluge, A.G.; Rowe, T. (1988). "The early evolution of the Amniota". In Benton, M.J. (ed.). The Phylogeny and Classification of the Tetrapods. 1. Oxford: Clarendon Press. pp. 103–155. ISBN 978-0-19-857705-8.
  357. ^ Laurin, M.; Reisz, R. R. (1995). "A reevaluation of early amniote phylogeny" (PDF). Zoological Journal of the Linnean Society. 113 (2): 165–223. doi:10.1111/j.1096-3642.1995.tb00932.x. Archived from the original (PDF) on 8 June 2019. Retrieved 14 August 2016.
  358. ^ Modesto, S.P. (1999). "Observations of the structure of the Early Permian reptile Stereosternum tumidum Cope". Palaeontologia Africana. 35: 7–19.
  359. ^ Rasmussen, Arne Redsted; Murphy, John C.; Ompi, Medy; Gibbons, J. Whitfield; Uetz, Peter (8 November 2011). "Marine Reptiles". PLOS ONE. 6 (11): e27373. Bibcode:2011PLoSO...627373R. doi:10.1371/journal.pone.0027373. PMC 3210815. PMID 22087300.
  360. ^ Stidworthy J. 1974. Snakes of the World. Grosset & Dunlap Inc. 160 pp. ISBN 0-448-11856-4.
  361. ^ Sea snakes at Food and Agriculture Organization of the United Nations. Accessed 22 August 2020.
  362. ^ Rasmussen, A.R.; Murphy, J.C.; Ompi, M.; Gibbons, J.W.; Uetz, P. (2011). "Marine reptiles". PLOS ONE. 6 (11): e27373. Bibcode:2011PLoSO...627373R. doi:10.1371/journal.pone.0027373. PMC 3210815. PMID 22087300.
  363. ^ Martill D.M. (1993). "Soupy Substrates: A Medium for the Exceptional Preservation of Ichthyosaurs of the Posidonia Shale (Lower Jurassic) of Germany". Kaupia - Darmstädter Beiträge zur Naturgeschichte, 2 : 77-97.
  364. ^ Gould, Stephen Jay (1993) "Bent Out of Shape" in Eight Little Piggies: Reflections in Natural History. Norton, 179–94. ISBN 9780393311396.
  365. ^ "Sardine Run Shark Feeding Frenzy Phenomenon in Africa". Archived from the original on 2 December 2008.
  366. ^ "The Society for Marine Mammalogy's Taxonomy Committee List of Species and subspecies". Society for Marine Mammalogy. October 2015. Archived from the original on 6 January 2015. Retrieved 23 November 2015.
  367. ^ Romer A. S. and Parsons T. S. (1986) The Vertebrate Body, page 96, Sanders College Publishing. ISBN 0030584469.
  368. ^ "Blue whale". World Wide Fund For Nature. Retrieved 15 August 2016.
  369. ^ Marino, Lori (2004). "Cetacean Brain Evolution: Multiplication Generates Complexity" (PDF). International Society for Comparative Psychology (17): 1–16. Archived from the original (PDF) on 16 September 2018. Retrieved 15 August 2016.
  370. ^ a b Campbell, Neil A.; Reece, Jane B.; Urry, Lisa Andrea; Cain, Michael L.; Wasserman, Steven Alexander; Minorsky, Peter V.; Jackson, Robert Bradley (2008). Biology (8 ed.). San Francisco: Pearson – Benjamin Cummings. ISBN 978-0-321-54325-7.
  371. ^ McNeill, J.; et al., eds. (2012). International Code of Nomenclature for algae, fungi, and plants (Melbourne Code), Adopted by the Eighteenth International Botanical Congress Melbourne, Australia, July 2011 (electronic ed.). International Association for Plant Taxonomy. Retrieved 14 May 2017.
  372. ^ Walsh PJ, Smith S, Fleming L, Solo-Gabriele H, Gerwick WH, eds. (2 September 2011). "Cyanobacteria and cyanobacterial toxins". Oceans and Human Health: Risks and Remedies from the Seas. Academic Press. pp. 271–296. ISBN 978-0-08-087782-2.
  373. ^ "The Rise of Oxygen - Astrobiology Magazine". Astrobiology Magazine. 30 July 2003. Retrieved 6 April 2016.
  374. ^ Flannery, D. T.; R.M. Walter (2012). "Archean tufted microbial mats and the Great Oxidation Event: new insights into an ancient problem". Australian Journal of Earth Sciences. 59 (1): 1–11. Bibcode:2012AuJES..59....1F. doi:10.1080/08120099.2011.607849. S2CID 53618061.
  375. ^ Rothschild, Lynn (September 2003). "Understand the evolutionary mechanisms and environmental limits of life". NASA. Archived from the original on 11 March 2012. Retrieved 13 July 2009.
  376. ^ Nadis S (December 2003). "The cells that rule the seas" (PDF). Scientific American. 289 (6): 52–3. Bibcode:2003SciAm.289f..52N. doi:10.1038/scientificamerican1203-52. PMID 14631732. Archived from the original (PDF) on 19 April 2014. Retrieved 2 June 2019.
  377. ^ "The Most Important Microbe You've Never Heard Of". npr.org.
  378. ^ Flombaum, P.; Gallegos, J. L.; Gordillo, R. A.; Rincon, J.; Zabala, L. L.; Jiao, N.; Karl, D. M.; Li, W. K. W.; Lomas, M. W.; Veneziano, D.; Vera, C. S.; Vrugt, J. A.; Martiny, A. C. (2013). "Present and future global distributions of the marine Cyanobacteria Prochlorococcus and Synechococcus". Proceedings of the National Academy of Sciences. 110 (24): 9824–9829. Bibcode:2013PNAS..110.9824F. doi:10.1073/pnas.1307701110. PMC 3683724. PMID 23703908.
  379. ^ Nabors, Murray W. (2004). Introduction to Botany. San Francisco, CA: Pearson Education, Inc. ISBN 978-0-8053-4416-5.
  380. ^ Allaby, M., ed. (1992). "Algae". The Concise Dictionary of Botany. Oxford: Oxford University Press.
  381. ^ Guiry MD (October 2012). "How many species of algae are there?". Journal of Phycology. 48 (5): 1057–63. doi:10.1111/j.1529-8817.2012.01222.x. PMID 27011267. S2CID 30911529.
  382. ^ a b Guiry, M.D.; Guiry, G.M. (2016). "Algaebase". www.algaebase.org. Retrieved 20 November 2016.
  383. ^ D. Thomas (2002). Seaweeds. Life Series. Natural History Museum, London. ISBN 978-0-565-09175-0.
  384. ^ Hoek, Christiaan; den Hoeck, Hoeck Van; Mann, David; Jahns, H.M. (1995). Algae : an introduction to phycology. Cambridge University Press. p. 166. ISBN 9780521316873. OCLC 443576944.
  385. ^ Treguer, P.; Nelson, D. M.; Van Bennekom, A. J.; Demaster, D. J.; Leynaert, A.; Queguiner, B. (1995). "The Silica Balance in the World Ocean: A Reestimate". Science. 268 (5209): 375–9. Bibcode:1995Sci...268..375T. doi:10.1126/science.268.5209.375. PMID 17746543. S2CID 5672525.
  386. ^ "King's College London - Lake Megachad". www.kcl.ac.uk. Retrieved 5 May 2018.
  387. ^ Gómez F (2012). "A checklist and classification of living dinoflagellates (Dinoflagellata, Alveolata)" (PDF). CICIMAR Océanides. 27 (1): 65–140. doi:10.37543/oceanides.v27i1.111. Archived from the original (PDF) on 27 November 2013.
  388. ^ Stoecker DK (1999). "Mixotrophy among Dinoflagellates". The Journal of Eukaryotic Microbiology. 46 (4): 397–401. doi:10.1111/j.1550-7408.1999.tb04619.x. S2CID 83885629.
  389. ^ Starckx, Senne (31 October 2012) A place in the sun - Algae is the crop of the future, according to researchers in Geel Flanders Today, Retrieved 8 December 2012
  390. ^ Duval, B.; Margulis, L. (1995). "The microbial community of Ophrydium versatile colonies: endosymbionts, residents, and tenants". Symbiosis. 18: 181–210. PMID 11539474.
  391. ^ Wernberg, T., Krumhansl, K., Filbee-Dexter, K. and Pedersen, M.F. (2019) "Status and trends for the world’s kelp forests". In: World seas: an environmental evaluation, pages 57–78). Academic Press. doi:10.1016/B978-0-12-805052-1.00003-6.
  392. ^ Mann, K.H. (1973). "Seaweeds: their productivity and strategy for growth". Science. 182 (4116): 975–981. Bibcode:1973Sci...182..975M. doi:10.1126/science.182.4116.975. PMID 17833778. S2CID 26764207.
  393. ^ Tunnell, John Wesley; Chávez, Ernesto A.; Withers, Kim (2007). Coral reefs of the southern Gulf of Mexico. Texas A&M University Press. p. 91. ISBN 978-1-58544-617-9.
  394. ^ Invasive Species Compendium: Caulerpa taxifolia (killer algae) Centre for Agriculture and Bioscience International. Updated: 6 November 2018.
  395. ^ Mandoli, DF (1998). "Elaboration of Body Plan and Phase Change during Development of Acetabularia: How Is the Complex Architecture of a Giant Unicell Built?". Annual Review of Plant Physiology and Plant Molecular Biology. 49: 173–198. doi:10.1146/annurev.arplant.49.1.173. PMID 15012232. S2CID 6241264.
  396. ^ Pierre Madl; Maricela Yip (2004). "Literature Review of Caulerpa taxifolia". BUFUS-Info. 19 (31).
  397. ^ Orth, R.J.; Carruthers, T.J.; Dennison, W.C.; Duarte, C.M.; Fourqurean, J.W.; Heck, K.L.; Hughes, A.R.; Kendrick, G.A.; Kenworthy, W.J.; Olyarnik, S.; Short, F.T. (2006). "A global crisis for seagrass ecosystems". BioScience. 56 (12): 987–996. doi:10.1641/0006-3568(2006)56[987:AGCFSE]2.0.CO;2. hdl:10261/88476.
  398. ^ Froese, Rainer and Pauly, Daniel, eds. (2009). "Phycodurus eques" in FishBase. July 2009 version.
  399. ^ Giri, C; Ochieng, E; Tieszen, LL; Zhu, Z; Singh, A; Loveland, T; et al. (2011). "Status and distribution of mangrove forests of the world using earth observation satellite data". Global Ecology and Biogeography. 20 (1): 154–159. doi:10.1111/j.1466-8238.2010.00584.x.
  400. ^ Thomas, N.; Lucas, R.; Bunting, P.; Hardy, A.; Rosenqvist, A.; Simard, M. (2017). "Distribution and drivers of global mangrove forest change, 1996–2010". PLOS ONE. 12 (6): e0179302. Bibcode:2017PLoSO..1279302T. doi:10.1371/journal.pone.0179302. PMC 5464653. PMID 28594908.
  401. ^ Short, F.T. and Frederick, T. (2003) World atlas of seagrasses, University of California Press, page 24. ISBN 9780520240476
  402. ^ Lalli, C.; Parsons, T. (1993). Biological Oceanography: An Introduction. Butterworth-Heinemann. ISBN 0-7506-3384-0.
  403. ^ Lindsey, R., Scott, M. and Simmon, R. (2010) "What are phytoplankton". NASA Earth Observatory.
  404. ^ Field, C. B.; Behrenfeld, M. J.; Randerson, J. T.; Falwoski, P. G. (1998). "Primary production of the biosphere: Integrating terrestrial and oceanic components". Science. 281 (5374): 237–240. Bibcode:1998Sci...281..237F. doi:10.1126/science.281.5374.237. PMID 9657713.
  405. ^ Rost, B. and Riebesell, U. (2004) "Coccolithophores and the biological pump: responses to environmental changes". In: Coccolithophores: From Molecular Processes to Global Impact, pages 99–125, Springer. ISBN 9783662062784.
  406. ^ Arsenieff, L.; Simon, N.; Rigaut-Jalabert, F.; Le Gall, F.; Chaffron, S.; Corre, E.; Com, E.; Bigeard, E.; Baudoux, A.C. (2018). "First Viruses Infecting the Marine Diatom Guinardia delicatula". Frontiers in Microbiology. 9: 3235. doi:10.3389/fmicb.2018.03235. PMC 6334475. PMID 30687251.
  407. ^ Varea, C.; Aragon, J.L.; Barrio, R.A. (1999). "Turing patterns on a sphere". Physical Review E. 60 (4): 4588–92. Bibcode:1999PhRvE..60.4588V. doi:10.1103/PhysRevE.60.4588. PMID 11970318.
  408. ^ Harvey, Edmund Newton (1952). Bioluminescence. Academic Press.
  409. ^ Suggested Explanation for Glowing Seas--Including Currently Glowing California Seas National Science Foundation, 18 October 2011.
  410. ^ Castro P, Huber ME (2010). Marine Biology (8th ed.). McGraw Hill. pp. 95. ISBN 978-0071113021.
  411. ^ Hastings JW (1996). "Chemistries and colors of bioluminescent reactions: a review". Gene. 173 (1 Spec No): 5–11. doi:10.1016/0378-1119(95)00676-1. PMID 8707056.
  412. ^ Haddock SH, Moline MA, Case JF (2009). "Bioluminescence in the sea". Annual Review of Marine Science. 2: 443–93. Bibcode:2010ARMS....2..443H. doi:10.1146/annurev-marine-120308-081028. PMID 21141672. S2CID 3872860.
  413. ^ U S Department of Energy (2008) Carbon Cycling and Biosequestration page 81, Workshop report DOE/SC-108, U.S. Department of Energy Office of Science.
  414. ^ Campbell, Mike (22 June 2011). "The role of marine plankton in sequestration of carbon". EarthTimes. Retrieved 22 August 2014.
  415. ^ Roman, J. & McCarthy, J.J. (2010). "The Whale Pump: Marine Mammals Enhance Primary Productivity in a Coastal Basin". PLOS ONE. 5 (10): e13255. Bibcode:2010PLoSO...513255R. doi:10.1371/journal.pone.0013255. PMC 2952594. PMID 20949007. e13255.CS1 maint: uses authors parameter (link)
  416. ^ Brown, Joshua E. (12 October 2010). "Whale poop pumps up ocean health". Science Daily. Retrieved 18 August 2014.
  417. ^ Thomson, Charles Wyville (2014) Voyage of the Challenger : The Atlantic Cambridge University Press, page235. ISBN 9781108074759.
  418. ^ Grethe R. Hasle; Erik E. Syvertsen; Karen A. Steidinger; Karl Tangen (25 January 1996). "Marine Diatoms". In Carmelo R. Tomas (ed.). Identifying Marine Diatoms and Dinoflagellates. Academic Press. pp. 5–385. ISBN 978-0-08-053441-1. Retrieved 13 November 2013.
  419. ^ Ald, S.M.; et al. (2007). "Diversity, Nomenclature, and Taxonomy of Protists" (PDF). Syst. Biol. 56 (4): 684–689. doi:10.1080/10635150701494127. PMID 17661235. Archived from the original (PDF) on 31 March 2011. Retrieved 1 October 2019.
  420. ^ Moheimani, N.R.; Webb, J.P.; Borowitzka, M.A. (2012), "Bioremediation and other potential applications of coccolithophorid algae: A review. . Bioremediation and other potential applications of coccolithophorid algae: A review", Algal Research, 1 (2): 120–133, doi:10.1016/j.algal.2012.06.002
  421. ^ Taylor, A.R.; Chrachri, A.; Wheeler, G.; Goddard, H.; Brownlee, C. (2011). "A voltage-gated H+ channel underlying pH homeostasis in calcifying coccolithophores". PLOS Biology. 9 (6): e1001085. doi:10.1371/journal.pbio.1001085. PMC 3119654. PMID 21713028.
  422. ^ "Water, the Universal Solvent". USGS. Archived from the original on 9 July 2017. Retrieved 27 June 2017.
  423. ^ Brum JR, Morris JJ, Décima M and Stukel MR (2014) "Mortality in the oceans: Causes and consequences". Eco-DAS IX Symposium Proceedings, Chapter 2, pages 16-48. Association for the Sciences of Limnology and Oceanography. ISBN 978-0-9845591-3-8.
  424. ^ Reece, Jane B. (2013). Campbell Biology (10 ed.). Pearson. ISBN 9780321775658.
  425. ^ Prentice, I.C. (2001). "The carbon cycle and atmospheric carbon dioxide". Climate change 2001: the scientific basis: contribution of Working Group I to the Third Assessment Report of the Intergouvernmental Panel on Climate Change / Houghton, J.T. [edit.] Retrieved 31 May 2012.
  426. ^ Halpern, B.S.; Frazier, M.; Afflerbach, J.; et al. (2019). "Recent pace of change in human impact on the world's ocean". Scientific Reports. 9 (1): 11609. Bibcode:2019NatSR...911609H. doi:10.1038/s41598-019-47201-9. PMC 6691109. PMID 31406130.
  427. ^ Human impacts on marine ecosystems GEOMAR Helmholtz Centre for Ocean Research. Retrieved 22 October 2019.
  428. ^ Rosing, M.; Bird, D.; Sleep, N.; Bjerrum, C. (2010). "No climate paradox under the faint early Sun". Nature. 464 (7289): 744–747. Bibcode:2010Natur.464..744R. doi:10.1038/nature08955. PMID 20360739. S2CID 205220182.
  429. ^ a b Sahney, S.; Benton, M.J.; Ferry, Paul (2010). "Links between global taxonomic diversity, ecological diversity and the expansion of vertebrates on land". Biology Letters. 6 (4): 544–7. doi:10.1098/rsbl.2009.1024. PMC 2936204. PMID 20106856.
  430. ^ McKinney 1997, p. 110
  431. ^ Stearns & Stearns 1999, p. x
  432. ^ Novacek, Michael J. (8 November 2014). "Prehistory's Brilliant Future". The New York Times. New York: The New York Times Company. ISSN 0362-4331. Retrieved 25 December 2014.
  433. ^ Nee, S. (2004). "Extinction, slime, and bottoms". PLOS Biology. 2 (8): E272. doi:10.1371/journal.pbio.0020272. PMC 509315. PMID 15314670.
  434. ^ Ward, Peter D (2006). "Impact from the Deep". Scientific American. 295 (4): 64–71. Bibcode:2006SciAm.295d..64W. doi:10.1038/scientificamerican1006-64. PMID 16989482.
  435. ^ Sahney, S. & Benton, M.J. (2008). "Recovery from the most profound mass extinction of all time". Proceedings of the Royal Society B: Biological Sciences. 275 (1636): 759–65. doi:10.1098/rspb.2007.1370. PMC 2596898. PMID 18198148.

Notes[edit]

  1. ^ The earliest Bilateria may have had only a single opening, and no coelom.[246]

Further references[edit]

  • Halpern, B.S.; Walbridge, S.; Selkoe, K.A.; Kappel, C.V.; Micheli, F.; D'Agrosa, C.; Bruno, J.F.; Casey, K.S.; Ebert, C.; Fox, H.E.; Fujita, R. (2008). "A global map of human impact on marine ecosystems". Science. 319 (5865): 948–952. Bibcode:2008Sci...319..948H. doi:10.1126/science.1149345. PMID 18276889. S2CID 26206024.
  • Paleczny, M.; Hammill, E.; Karpouzi, V.; Pauly, D. (2015). "Population trend of the world's monitored seabirds, 1950-2010". PLOS ONE. 10 (6): e0129342. Bibcode:2015PLoSO..1029342P. doi:10.1371/journal.pone.0129342. PMC 4461279. PMID 26058068.
  • After 60 million years of extreme living, seabirds are crashing The Guardian, 22 September 2015.
  • Ruppert, E.E.; Fox, R.S. & Barnes, R.D. (2004). Invertebrate Zoology (7th ed.). Brooks / Cole. ISBN 978-0-03-025982-1.