Sea snail is a

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...

for slow-moving

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military ...

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

molluscs, usually with visible external shells, such as whelk or

abalone Abalone ( or ; via Spanish , from Rumsen ''aulón'') is a common name for any of a group of small to very large marine gastropod molluscs in the family Haliotidae. Other common names are ear shells, sea ears, and, rarely, muttonfish or mutto ...

. They share the taxonomic class Gastropoda with

slugs Slug, or land slug, is a common name for any apparently shell-less terrestrial molluscs, terrestrial gastropod mollusc. The word ''slug'' is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced ...

, which are distinguished from snails primarily by the absence of a visible shell.

Definition

Determining whether some gastropods should be called sea snails is not always easy. Some species that live in brackish water (such as certain neritids) can be listed as either

freshwater snails Freshwater snails are gastropod mollusks which live in fresh water. There are many different families. They are found throughout the world in various habitats, ranging from ephemeral pools to the largest lakes, and from small seeps and springs ...

or marine snails, and some species that live at or just above the high tide level (for example species in the genus '' Truncatella'') are sometimes considered to be sea snails and sometimes listed as land snails.

Anatomy

Sea snails are a very large group of animals and a very diverse one. Most snails that live in

salt water Saline water (more commonly known as salt water) is water that contains a high concentration of dissolved salts (mainly sodium chloride). On the United States Geological Survey (USGS) salinity scale, saline water is saltier than brackish w ...

respire using a

gill A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they ar ...

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 ''Trimusculus'' is a genus of medium-sized air-breathing sea snails or false limpets, marine pulmonate gastropod molluscs in the family Trimusculidae. ''Trimusculus'' is the only genus in the family Trimusculidae. Trimusculidae, the butt ...

. Many, but not all, sea snails have an operculum.

Shell

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 Juliidae, common name the bivalved gastropods, is a family of minute sea snails, marine gastropod mollusks or micromollusks in the superfamily Oxynooidea, an opisthobranch group. MolluscaBase eds. (2021). MolluscaBase. Juliidae E. A. Smith, ...

), the shell of the snail has become two hinged plates closely resembling those of a

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of marine and freshwater Mollusca, molluscs that have laterally compressed bodies enclosed by a shell consisting of two hing ...

; 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 ''Syrinx aruanus'', common name the Australian trumpet or false trumpet, is a species of extremely large sea snail measuring up to 91 cm long and weighing up to 18 kg. It is a marine gastropod mollusk in the family Turbinellidae, ...

'', the largest living shelled gastropod species at , 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. The shells of snails are complex and grow at different speeds. The speed of growth is affected by a few variables such as the temperature of the water, depth of the water, food present for the snail, as well as isotopic oxygen levels. By looking at the composition of aragonite in the growth layers of

mollusks Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

you can predict the size the mollusk shell can reach.

Taxonomy

2005 taxonomy

The following cladogram is an overview of the main clades of living gastropods based on the taxonomy of Bouchet & Rocroi (2005), with taxa that contain saltwater or brackish water species marked in boldface (some of the highlighted taxa consist entirely of marine species, but some of them also contain freshwater or land species.) * Clade Patellogastropoda * Clade Vetigastropoda * Clade

Cocculiniformia The Cocculinoidea is a superfamily of deepwater limpets (marine gastropods), the only superfamily in the order Cocculinida , one of the main orders of gastropods according to the taxonomy as set up by ( Bouchet & Rocroi, 2005). The clade Coccilin ...

* Clade Neritimorpha ** Clade

Cycloneritimorpha Cycloneritida (nerites and false-limpets) is an order of land snails, freshwater snails, and sea snails.MolluscaBase eds. (2020). MolluscaBase. Cycloneritida. Accessed through: World Register of Marine Species at: http://www.marinespecies.org/aph ...

* Clade

Caenogastropoda Caenogastropoda is a taxonomic clade, a large diverse group which are mostly sea snails and other marine gastropod mollusks, but also includes some freshwater snails and some land snails. The clade is the most diverse and ecologically successfu ...

** Informal group

Architaenioglossa Architaenioglossa is a taxonomic group of snails which have gills and often an operculum. They are primarily land and freshwater gastropod mollusks within the clade Caenogastropoda. This " informal group" has been shown to be polyphyletic in a ...

** Clade Sorbeoconcha ** Clade Hypsogastropoda *** Clade Littorinimorpha *** Informal group

Ptenoglossa The Ptenoglossa is an informal taxonomic group of sea snails. This group was considered paraphyletic or polyphyletic by Ponder and Lindberg (1997) in their classification of gastropod The gastropods (), commonly known as snails and slugs, belo ...

*** Clade Neogastropoda * Clade Heterobranchia ** Informal group Lower Heterobranchia ** Informal group

Opisthobranchia Opisthobranchs () is now an informal name for a large and diverse group of specialized complex gastropods which used to be united in the subclass Opisthobranchia. That taxon is no longer considered to represent a monophyletic grouping. Euopi ...

*** Clade Cephalaspidea *** Clade Thecosomata *** Clade Gymnosomata *** Clade Aplysiomorpha *** Group Acochlidiacea *** Clade Sacoglossa *** Group Cylindrobullida *** Clade Umbraculida *** Clade Nudipleura **** Clade

Pleurobranchomorpha The Pleurobranchidae are a taxonomic family of sea slugs, marine gastropod molluscs in the clade Pleurobranchomorpha. Characteristics Species in the family Pleurobranchidae have a prominent mantle and an internal shell that becomes reduc ...

**** Clade Nudibranchia ***** Clade Euctenidiacea ***** Clade Dexiarchia ****** Clade Pseudoeuctenidiacea ****** Clade Cladobranchia ******* Clade Euarminida ******* Clade

Dendronotida Dendronotoidea is a Taxonomy (biology), taxonomic superfamily (zoology), superfamily of small colorful sea slugs or nudibranchs, aeolid nudibranchs. MolluscaBase eds. (2022). MolluscaBase. Dendronotoidea Allman, 1845. Accessed through: World Re ...

******* Clade

Aeolidida The Aeolidida is a taxonomic clade of sea slugs, specifically aeolid nudibranchs, marine gastropod molluscs in the clade Cladobranchia. They are distinguished from other nudibranchs by their possession of cerata containing cnidosacs. Ta ...

** Informal group Pulmonata *** Informal group

Basommatophora Basommatophora was a term that was previously used as a taxonomic informal group, a group of snails within the informal group Pulmonata, the air-breathing slugs and snails. According to the taxonomy of the Gastropoda (Bouchet & Rocroi, 2005), whe ...

*** Clade Eupulmonata **** Clade Systellommatophora **** Clade

Stylommatophora Stylommatophora is an orderPhilippe Bouchet, Jean-Pierre Rocroi, Bernhard Hausdorf, Andrzej Kaim, Yasunori Kano, Alexander Nützel, Pavel Parkhaev, Michael Schrödl and Ellen E. Strong. 2017. Revised Classification, Nomenclator and Typification ...

***** Clade Elasmognatha ***** Clade

Orthurethra Orthurethra is a clade of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the clade Stylommatophora. In the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005, Orthurethra is treated as an informal group and subcl ...

***** Informal group

Sigmurethra Sigmurethra is a taxonomic category of air-breathing land snails and slugs, terrestrial pulmonate gastropod molluscs. This is an informal group which includes most land snails and slugs. The two strong synapomorphies of Sigmurethra are a lo ...

Uses

By humans

A number of species of sea snails are harvested in

aquaculture Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. lot ...

and used by humans for food, including

conch Conch () is a common name of a number of different medium-to-large-sized sea snails. Conch shells typically have a high spire and a noticeable siphonal canal (in other words, the shell comes to a noticeable point at both ends). In North Am ...

, limpets, whelks (such as the North American ''

Busycon ''Busycon'' is a genus of very large edible sea snails in the subfamily Busyconinae. These snails are commonly known in the United States as ''whelks'' or ''Busycon whelks''. Less commonly they are loosely, and somewhat misleadingly, called "con ...

'' species and the North Atlantic ''

Buccinum undatum ''Buccinum undatum'', the common whelk or the waved buccinum, is a large, edible marine gastropod in the family Buccinidae, the "true whelks".Fraussen, K.; Gofas, S. (2014). Buccinum undatum Linnaeus, 1758. Accessed through: World Register of ...

'') and periwinkles including '' Littorina littorea''. The shells of sea snails are often found washed up on

beach A beach is a landform alongside a body of water which consists of loose particles. The particles composing a beach are typically made from rock, such as sand, gravel, shingle, pebbles, etc., or biological sources, such as mollusc s ...

es. Because many are attractive and durable, they have been used to make necklaces and other

jewelry Jewellery ( UK) or jewelry ( U.S.) consists of decorative items worn for personal adornment, such as brooches, rings, necklaces, earrings, pendants, bracelets, and cufflinks. Jewellery may be attached to the body or the clothes. From a w ...

since prehistoric times. The shells of a few species of large sea snails within the Vetigastropoda have a thick layer of

nacre Nacre ( , ), also known as mother of pearl, is an organicinorganic composite material produced by some molluscs as an inner shell layer; it is also the material of which pearls are composed. It is strong, resilient, and iridescent. Nacre is ...

and have been used as a source of mother of pearl. Historically, the button industry relied on these species for a number of years.

By non-human animals

The shells of sea snails are used for protection by many kinds of hermit crabs. A hermit crab carries the shell by grasping the central columella of the shell using claspers on the tip of its abdomen.

References

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