Marine snails

Sea snail is a common name for snails that normally live in saltwater, in other words marine gastropods. The taxonomic class Gastropoda also includes snails that live in other habitats, such as land snails and freshwater snails. Many species of sea snails are edible and exploited as food sources by humans.

Sea snails are marine gastropods with shells. Those marine gastropods with no shells, or only internal shells, are variously known by other common names, including sea slug, sea hare, nudibranch, etc. The diversity within sea snails is enormous. Many very different clades of gastropods are either dominated by, or consist exclusively of, sea snails. Because of this great variability, generalization about the feeding, reproduction, habitat, or other traits of sea snails is not possible. Instead, individual clades, families, genera, or species must be assessed.

The shells of most species of sea snails are spirally coiled. Some, though, have conical shells, and these are often referred to by the common name of limpets. In one unusual family (Juliidae), the shell of the snail has become two hinged plates closely resembling those of a bivalve; this family is sometimes called the "bivalved gastropods".

Their shells are found in a variety of shapes and sizes, but are normally very small. Those of living species of sea snails range in size from Syrinx aruanus, the largest living shelled gastropod species at 91 cm, to minute species whose shells are less than 1 mm at adult size. Because the shells of sea snails are strong and durable in many cases, as a group they are well represented in the fossil record.

Sea snails are a very large group of animals and a very diverse one. Most snails that live in saltwater respire using a gill or gills, a few species, though, have a lung, are intertidal, and are active only at low tide when they can move around in the air. These air-breathing species include false limpets in the family Siphonariidae and another group of false limpets in the family Trimusculidae.

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