Sea butterfly
Limacinidae
Cavoliniidae
Clionidae
Creseidae
Cuvierinidae
Praecuvierinidae
Peraclididae
Cymbuliidae
Desmopteridae
Sea butterflies, scientific name Thecosomata (thecosomes,[1] "case / shell-body"[2]), are a taxonomic suborder of small pelagic swimming sea snails. They are holoplanktonic opisthobranch gastropod mollusks. Most Thecosomata have some form of calcified shell, although it is often very light and / or transparent.[3]
The sea butterflies include some of the world's most abundant gastropod species,[1]and because of their large numbers are an essential part of the food chain, and a significant contributor to the oceanic carbon cycle.[3][4]
The sea butterflies are included in the Pteropoda order, and are also included in the informal group Opisthobranchia.
Sea butterflies float and swim freely in the water, and are carried along with the currents. This has led to a number of adaptations in their bodies. The shell and the gill have disappeared in several families. Their gastropodal foot has taken the form of two wing-like lobes, or parapodia, which propel the animal through the sea by slow flapping movements.
Most Thecosomata have some form of calcified shell, although often very light.[3]They are rather difficult to see, since their shell (if present) is mostly transparent, very fragile, and usually tiny: Less than 1 cm in length. Although their shell may be so fine as to be transparent, it is nevertheless calcareous, and an important part of the ocean calcite cycle.[4]Their shells are bilaterally symmetric and can vary widely in shape: coiled, needle-like, triangular, or globular.
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