''Limacina'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of swimming

predatory Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill ...

sea snail Sea snails are slow-moving marine (ocean), marine gastropod Mollusca, molluscs, usually with visible external shells, such as whelk or abalone. They share the Taxonomic classification, taxonomic class Gastropoda with slugs, which are distinguishe ...

s commonly known as

sea butterflies The Thecosomata (collective/plural: ''thecosomes'', meaning "case/shell-body"), or sea butterflies, are a taxonomic suborder of small, pelagic, free-swimming sea snails known as holoplanktonic opisthobranch gastropod mollusks, in the order ...

in the family

Limacinidae The Limacinidae are a family of small sea snails, pteropods, pelagic marine gastropod mollusks in the clade Thecosomata (sea butterflies The Thecosomata (collective/plural: ''thecosomes'', meaning "case/shell-body"), or sea butterflies, are ...

. This genus contains some of the world's most abundant gastropod species.Bouchet, P.; Gofas, S. (2012). Limacina. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=138122 on 2012-07-18

Etymological Etymology ( ) is the study of the origin and evolution of words—including their constituent units of sound and meaning—across time. In the 21st century a subfield within linguistics, etymology has become a more rigorously scientific study. ...

meaning of the generic name ''Limacina'' is "snail-like". As

pelagic The pelagic zone consists of the water column of the open ocean and can be further divided into regions by depth. The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or water column between the sur ...

marine

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

s, ''Limacina'' swim by flapping their

parapodia In invertebrates, the term parapodium ( Gr. ''para'', beyond or beside + ''podia'', feet; : parapodia) refers to lateral outgrowths or protrusions from the body. Parapodia are predominantly found in annelids, where they are paired, unjointed late ...

, inspiring the

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 con ...

. Sea butterflies are part of the

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

Thecosomata The Thecosomata (collective/plural: ''thecosomes'', meaning "case/shell-body"), or sea butterflies, are a taxonomic suborder of small, pelagic, free-swimming sea snails known as holoplanktonic opisthobranch gastropod mollusks, in the order Pt ...

Sea angels A sea is a large body of salt water. There are particular seas and the sea. The sea commonly refers to the ocean, the interconnected body of seawaters that spans most of Earth. Particular seas are either marginal seas, second-order section ...

, similar to ''Limacina'', are in the order

Gymnosomata Sea angels (clade Gymnosomata) are a large group of small free-swimming sea slugs, classified into six separate families. They are pelagic opisthobranchs in the clade Gymnosomata within the larger mollusc clade Heterobranchia. Sea angels were pre ...

. Both of these orders are still referred to as "

pteropods Pteropoda (common name pteropods, from the Greek meaning "wing-foot") are specialized free-swimming pelagic sea snails and sea slugs, marine opisthobranch gastropods. Most live in the top 10 m of the ocean and are less than 1 cm long. ...

". Sea butterflies of the order Thecosomata have a shell, while sea angels in the order Gymnosomata do not.

Shell description

The shells of ''Limacina'' are well developed, sinistrally coiled, turret-like, and include an operculum. Shell size and thickness vary within the genus. At high latitudes, the diameter of the shell does not exceed 15 mm. At lower latitudes, the diameter varies from 1 to 3 mm.

Description of the soft parts

Two large winglike parapodia, derived from foot tissue, propel these

invertebrates Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordate subphylum ...

through the water column to overcome negative buoyancy due to the animal's shell. As diel vertical migrators, ''Limacina'' inhabit deeper waters during the day and travel to the surface at night to feed.

Life habits

Feeding habits of ''Limacina'' are characterized by actively feeding on planktonic organisms such as

bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...

, small

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

s, gastropod

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

dinoflagellate The Dinoflagellates (), also called Dinophytes, are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered protists. Dinoflagellates are mostly marine plankton, but they are also commo ...

s and

diatom A diatom (Neo-Latin ''diatoma'') is any member of a large group comprising several Genus, genera of algae, specifically microalgae, found in the oceans, waterways and soils of the world. Living diatoms make up a significant portion of Earth's B ...

s. These prey items become entangled in a mucosal web (up to 5 cm wide) excreted by the animal that is, in turn, eaten along with the prey items. This net also provides positive buoyancy. Ciliated posterior footlobes and lateral footlobes move food collected by the mucosal web into the mouth. Large aggregations of ''Limacina'' migrating to the surface of the water attract predators such as ''Clione'' (family

Clionidae The Clionidae are a family of sea angels, which are a group of pelagic marine gastropods. They resemble angels, complete with flapping "wings", hence their common name. They are gelatinous, mostly transparent pteropods, and they only have sh ...

, suborder

baleen whale Baleen whales (), also known as whalebone whales, are marine mammals of the order (biology), parvorder Mysticeti in the infraorder Cetacea (whales, dolphins and porpoises), which use baleen plates (or "whalebone") in their mouths to sieve plankt ...

s, various species of

salmonid Salmonidae (, ) is a family of ray-finned fish, the only extant member of the suborder Salmonoidei, consisting of 11 extant genera and over 200 species collectively known as "salmonids" or "salmonoids". The family includes salmon (both Atlantic a ...

s, herring, and

seabird Seabirds (also known as marine birds) are birds that are adaptation, adapted to life within the marine ecosystem, marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent ...

Species

Species within the genus ''Limacina'' include: * † ''

Limacina atypica ''Limacina'' is a genus of swimming predatory sea snails commonly known as sea butterflies in the family Limacinidae. This genus contains some of the world's most abundant gastropod species.Bouchet, P.; Gofas, S. (2012). Limacina. Accessed throu ...

'' (Laws, 1944) * (recent) '' Limacina bulimoides'' (

d'Orbigny Alcide Charles Victor Marie Dessalines d'Orbigny (6 September 1802 – 30 June 1857) was a French naturalist who made major contributions in many areas, including zoology (including malacology), palaeontology, geology, archaeology and anthropol ...

, 1836) - Bulimoid pteropod. Distribution: Red Sea, Pacific. Length: 1.2 mm. * † '' Limacina erasmiana'' Janssen, 2010Janssen A. W. (2010). "Pteropods (Mollusca, Euthecosomata) from the Early Eocene of Rotterdam (The Netherlands)". ''

Scripta Geologica ''Scripta Geologica'' is a peer-reviewed scientific journal that publishes on vertebrate and invertebrate palaeontology, palaeobotany/palynology, stratigraphy, petrology, and mineralogy, including gemmology with a focus on systematics. It is publis ...

'' 07 http://www.scriptageologica.nl/10/nr007/a09 * † '' Limacina dilatata'' (Koenen, 1892) * † '' Limacina ferax'' (Laws, 1944) * † '' Limacina gormani'' (Curry, 1982) * † '' Limacina guersi'' Janssen, 2010 * (recent) ''

Limacina helicina ''Limacina helicina'' is a species of small swimming planktonic sea snail, in the family Limacinidae. It belongs to the group commonly known as Sea butterfly, sea butterflies (Thecosomata). ''Limacina helicina'' is a keystone species of mesozoo ...

'' (Phipps, 1774) - Helicid pteropod. Type species.Janssen A. W. (2007). "Holoplanktonic Mollusca (Gastropoda: Pterotracheoidea, Janthinoidea, Thecosomata and Gymnosomata) from the Pliocene of Pangasinan (Luzon, Philippines)". ''

'' 137 http://www.scriptageologica.nl/07/nr135/a02 * (recent) '' Limacina lesueurii'' (d'Orbigny, 1836) - Distribution: North America, Western Atlantic. * † '' Limacina limata'' (Marwick, 1926) * † '' Limacina pygmaea'' (Lamarck, 1805) * (recent) '' Limacina rangii'' (d'Orbigny, 1834) * (recent) '' Limacina retroversa'' (Fleming, 1823) - Retrovert pteropod. Distribution: North America, Western Atlantic, Arctic Ocean. * † '' Limacina sculptilis'' (Maxwell, 1992) * † '' Limacina taylori'' (Curry, 1965) * (recent) '' Limacina trochiformis'' (d'Orbigny, 1836) - Trochiform pteropod. Distribution: North America, Western Atlantic, Red Sea, Pacific. Length: 1 mm. * † '' Limacina valvatina'' (Reuss, 1867) * † '' Limacina? vegrandis'' Cahuzac & Janssen, 2010Cahuzac B. & Janssen A. W. (2010). "Eocene to Miocene holoplanktonic Mollusca (Gastropoda) of the Aquitaine Basin, southwest France". ''

'' 141: http://www.scriptageologica.nl/10/nr141/a01 ;Species brought into synonymy: * (recent) ''Limacina antarctica'' Woodward, 1854:WoRMS (2010). ''Limacina antarctica'' Woodward, 1854. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=509607 on 2011-01-29 synonym of ''Limacina rangii'' f. ''antarctica'' Woodward, 1854: synonym of ''Limacina rangii'' (d'Orbigny, 1834) * ''Limacina balea'' Møller, 1841: synonym of ''Limacina retroversa'' (Fleming, 1823) * ''Limacina contorta'' Sykes, 1905: synonym of ''Limacina trochiformis'' (d'Orbigny, 1834) * ''Limacina crossei'' Pelseneer, 1888: synonym of ''Limacina lesueurii'' (d'Orbigny, 1835) * ''Limacina cucullata'' Gould, 1852: synonym of ''Limacina rangii'' f. ''antarctica'' Woodward, 1854: synonym of ''Limacina rangii'' (d'Orbigny, 1834) * ''Limacina helicialis'' Lamarck, 1819: synonym of ''Limacina helicina'' (Phipps, 1774) * (recent) ''Limacina helicoides'' Jeffreys, 1877 - synonym of '' Thielea helicoides'' (Jeffreys, 1877) * (recent) ''Limacina inflata'' (d'Orbigny, 1836) - Planorbid pteropod. Distribution: circumglobal, Red Sea, Pacific. Length: 1 mm. Description: the shell is flatly twisted, resembling the shell of the cephalopod

Nautilus A nautilus (; ) is any of the various species within the cephalopod family Nautilidae. This is the sole extant family of the superfamily Nautilaceae and the suborder Nautilina. It comprises nine living species in two genera, the type genus, ty ...

. - synonym: '' Heliconoides inflata'' (d'Orbigny, 1836) * ''Limacina naticoides'' Souleyet, 1852: synonym of ''Limacina trochiformis'' (d'Orbigny, 1834) * ''Limacina pacifica'' Dall, 1871: synonym of ''Limacina helicina pacifica'' Dall, 1871 * ''Limacina scaphoidea'' Gould, 1852: synonym of ''

Heliconoides inflatus Heliconoides inflatus is a species of sea butterfly, a type of pteropod. Description Sinistrally coiled, involute pigmented shell. Has large paired fins. Right tentacle is much larger than the left. Distribution The species is found in the ...

'' (d'Orbigny, 1834)

References

* Vaught, K.C. (1989). ''A classification of the living Mollusca''. American Malacologists: Melbourne, FL (USA). . XII, 195 pp. * Gofas, S.; Le Renard, J.; Bouchet, P. (2001). Mollusca, in: Costello, M.J. et al. (Ed.) (2001). ''European register of marine species: a check-list of the marine species in Europe and a bibliography of guides to their identification''. Collection Patrimoines Naturels, 50: pp. 180–213 {{Taxonbar, from=Q3202503 Limacinidae Gastropod genera Taxa named by Louis Augustin Guillaume Bosc