The Exocoetidae are a family of marine fish in the order Beloniformes class Actinopterygii, known colloquially as flying fish or flying cod. About 64 species are grouped in seven to nine genera. While they cannot fly in the same way a bird does, flying fish can make powerful, self-propelled leaps out of the water where their long wing-like fins enable gliding for considerable distances above the water's surface. The main reason for this behavior is thought to be to escape from underwater predators,[3][4][5] which include swordfish, mackerel, tuna, and marlin, among others,[6] though their periods of flight expose them to attack by avian predators such as frigate birds.
Barbados is known as "the land of the flying fish", and the fish is one of the national symbols of the country. The Exocet missile is named after them, as variants are launched from underwater, and take a low trajectory, skimming the surface, before striking their targets.
The oldest known fossil of a flying or gliding fish, Potanichthys xingyiensis, dates back to the Middle Triassic, 235–242 million years ago.[7] However, this fossil is probably not related to modern flying fish, which are thought to have evolved independently about 66 million years ago[citation needed].[8]
The term Exocoetidae is both the scientific name and the general name in Latin for a flying fish. The suffix -idae, common for indicating a family, follows the root of the Latin word exocoetus, a transliteration of the Ancient Greek name ἐξώκοιτος. This means literally "sleeping outside", from ἔξω "outside" and κοῖτος "bed", "resting place", verb root κει- "to lie down" (not "untruth"),[9] so named as flying fish were believed to leave the water to sleep ashore,[10] or due to flying fish flying and thus stranding themselves in boats.
Flying fish live in all of the oceans, particularly in tropical and warm subtropical waters. They are commonly found in the epipelagic zone, the top layer of the ocean to a depth of about 200 m (656 ft).
Numerous morphological features give flying fish the ability to leap above the surface of the ocean. One such feature is fully broadened neural arches, which act as insertion sites for connective tissues and ligaments in a fish's skeleton. Fully broadened neural arches act as more stable and sturdier sites for these connections, creating a strong link between the vertebral column and cranium.[13] This ultimately allows a rigid and sturdy vertebral column (body) that is beneficial in flight. Having a rigid body during glided flight gives the flying fish aerodynamic advantages, increasing its speed and improving its aim.[13] Furthermore, flying fish have developed vertebral columns and ossified caudal complexes.[14] These features provide the majority of strength to the flying fish, allowing them to physically lift their bodies out of water and glide remarkable distances. These additions also reduce the flexibility of the flying fish, allowing them to perform powerful leaps without weakening midair.[14] At the end of a glide, they fold their pectoral fins to re-enter the sea, or drop their tails into the water to push against the water to lift for another glide, possibly changing direction.[15][16] The curved profile of the "wing" is comparable to the aerodynamic shape of a bird wing.[17] The fish is able to increase its time in the air by flying straight into or at an angle to the direction of updrafts created by a combination of air and ocean currents.[15][16]