''Limacina helicina'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of small swimming

planktonic Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucia ...

sea snail Sea snail is a common name for slow-moving marine gastropod molluscs, usually with visible external shells, such as whelk or abalone. They share the taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the ...

in the family

Limacinidae The Limacinidae are a family of small sea snails, pteropods, pelagic marine gastropod mollusks in the clade Thecosomata ( sea butterflies).Bouchet, P. (2012). Limacinidae. Accessed through: World Register of Marine Species at http://www.marinesp ...

, which belong to the group commonly known as

sea butterflies Sea butterflies, scientific name Thecosomata (thecosomes, "case / shell-body"), are a taxonomic suborder of small pelagic swimming sea snails. They are holoplanktonic opisthobranch gastropod mollusks. Most Thecosomata have some form of calcifi ...

(

Thecosomata Sea butterflies, scientific name Thecosomata (thecosomes, "case / shell-body"), are a taxonomic suborder of small pelagic swimming sea snails. They are holoplanktonic opisthobranch gastropod mollusks. Most Thecosomata have some form of calcified ...

). ''Limacina helicina'' is a

keystone species A keystone species is a species which has a disproportionately large effect on its natural environment relative to its abundance, a concept introduced in 1969 by the zoologist Robert T. Paine. Keystone species play a critical role in maintaini ...

mesozooplankton Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...

Arctic The Arctic ( or ) is a polar regions of Earth, polar region located at the northernmost part of Earth. The Arctic consists of the Arctic Ocean, adjacent seas, and parts of Canada (Yukon, Northwest Territories, Nunavut), Danish Realm (Greenla ...

pelagic The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or wa ...

ecosystems. The first written record of this species was by Friderich Martens from

Spitsbergen Spitsbergen (; formerly known as West Spitsbergen; Norwegian: ''Vest Spitsbergen'' or ''Vestspitsbergen'' , also sometimes spelled Spitzbergen) is the largest and the only permanently populated island of the Svalbard archipelago in northern Norw ...

in 1675. ''Limacina helicina'' was also observed during a 1773 expedition to the

led by Constantine John Phipps on the ships HMS ''Racehorse'' and on HMS ''Carcass'' and the species was described one year later, in 1774. ''Limacina helicina'' is the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

of the genus ''Limacina''. In contrast to the traditional view, it was shown in 2010 that the distribution of this species is not bipolar; Arctic and Antarctic individuals belong to two genetically distinct species: ''Limacina helicina'' in the Arctic, and ''

Limacina antarctica ''Limacina rangii'' is a species of swimming sea snail in the family Limacinidae,Bouchet, P. (2014). Limacina rangii (d'Orbigny, 1834). Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id ...

'' in the Antarctic.

Subspecies

* ''Limacina helicina helicina'' (Phipps, 1774)Bouchet, P.; Gofas, S. (2011). Limacina helicina (Phipps, 1774). Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=140223 on 2011-01-29 * ''Limacina helicina acuta'' Van Der Spoel, 1967 * ''Limacina helicina ochotensis'' Shkoldina, 1999 * ''Limacina helicina pacifica'' Dall, 1871 ''Limacina helicina'' has been recognised as a species complex comprising two sub-species and at least five

forms Form is the shape, visual appearance, or configuration of an object. In a wider sense, the form is the way something happens. Form also refers to: *Form (document), a document (printed or electronic) with spaces in which to write or enter data * ...

. In addition, the taxonomic category “forma” has been applied to designate at least three morphotypes of ''Limacina helicina helicina'' (''acuta'', ''helicina'' and ''pacifica'') and two morphotypes of ''Limacina helicina antarctica'' (''antarctica'' and ''rangi''). It is also known as ''Limacina helicina rangii'' (d'Orbigny, 1835). These forms typically have different geographical ranges, but it remains unclear as to whether forms represent morphological responses to different environmental conditions or are indeed taxonomically distinct, and if the latter, their level of taxonomic separation. However, at the species level the geographical distribution is considered to be bipolar, as it occurs in both the Arctic and

Antarctic The Antarctic ( or , American English also or ; commonly ) is a polar region around Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica, the Kerguelen Plateau and other ...

oceans. Remigio and Hebert (2003) provided initial evidence for the genetic separation of ''Limacina helicina helicina'' and ''Limacina helicina antarctica''. Hunt et al. (2010) have quantified

genetic distance Genetic distance is a measure of the genetic divergence between species or between populations within a species, whether the distance measures time from common ancestor or degree of differentiation. Populations with many similar alleles have sma ...

within these taxa. Hunt 2010 found a 33.56% difference in

cytochrome c oxidase subunit I Cytochrome c oxidase I (COX1) also known as mitochondrially encoded cytochrome c oxidase I (MT-CO1) is a protein that in humans is encoded by the ''MT-CO1'' gene. In other eukaryotes, the gene is called ''COX1'', ''CO1'', or ''COI''. Cytochro ...

(COI) gene sequences between the "''Limacina helicina''" which were collected from the Arctic and the Antarctic oceans. This degree of separation is sufficient for ordinal level taxonomic separation in other organisms, and provides strong evidence for the Arctic and Antarctic populations of ''Limacina helicina'' differing at least at the

level. Subspecies ''Limacina helicina antarctica'' Woodward, 1854 can be considered as a separate species ''

'' Woodward, 1854. A conservative divergence time estimate of 31 Ma (95% HPD interval 12–53 Ma) for Arctic and Antarctic taxa, indicates that they have undergone rapid independent

evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...

since the establishment of cold water provinces in the

early Oligocene The Rupelian is, in the geologic timescale, the older of two ages or the lower of two stages of the Oligocene Epoch/Series. It spans the time between . It is preceded by the Priabonian Stage (part of the Eocene) and is followed by the Chatti ...

. Also there is different structure of the shell between ''Limacina helicina'' and ''Limacina antarctica''.

Distribution

The type locality of ''Limacina helicina'' is "Arctic seas". ''Limacina helicina'' is the only thecosome pteropod in Arctic waters. The distribution of ''Limacina helicina'' is

arctic The Arctic ( or ) is a polar regions of Earth, polar region located at the northernmost part of Earth. The Arctic consists of the Arctic Ocean, adjacent seas, and parts of Canada (Yukon, Northwest Territories, Nunavut), Danish Realm (Greenla ...

and

subarctic The subarctic zone is a region in the Northern Hemisphere immediately south of the true Arctic, north of humid continental regions and covering much of Alaska, Canada, Iceland, the north of Scandinavia, Siberia, and the Cairngorms. Generally, ...

( subpolar–

polar Polar may refer to: Geography Polar may refer to: * Geographical pole, either of two fixed points on the surface of a rotating body or planet, at 90 degrees from the equator, based on the axis around which a body rotates * Polar climate, the c ...

) especially in the

Arctic Ocean The Arctic Ocean is the smallest and shallowest of the world's five major oceans. It spans an area of approximately and is known as the coldest of all the oceans. The International Hydrographic Organization (IHO) recognizes it as an ocean, a ...

and countries include: * Northern Atlantic Ocean between 50–60 °N,

Norwegian Sea The Norwegian Sea ( no, Norskehavet; is, Noregshaf; fo, Norskahavið) is a marginal sea, grouped with either the Atlantic Ocean or the Arctic Ocean, northwest of Norway between the North Sea and the Greenland Sea, adjoining the Barents Sea to ...

Faroe Islands The Faroe Islands ( ), or simply the Faroes ( fo, Føroyar ; da, Færøerne ), are a North Atlantic island group and an autonomous territory of the Kingdom of Denmark. They are located north-northwest of Scotland, and about halfway bet ...

, North of

Iceland Iceland ( is, Ísland; ) is a Nordic island country in the North Atlantic Ocean and in the Arctic Ocean. Iceland is the most sparsely populated country in Europe. Iceland's capital and largest city is Reykjavík, which (along with its s ...

* Greenland:

Denmark Strait The Denmark Strait () or Greenland Strait ( , 'Greenland Sound') is an oceanic strait between Greenland to its northwest and Iceland to its southeast. The Norwegian island of Jan Mayen lies northeast of the strait. Geography The strait connect ...

and

Davis Strait Davis Strait is a northern arm of the Atlantic Ocean that lies north of the Labrador Sea. It lies between mid-western Greenland and Baffin Island in Nunavut, Canada. To the north is Baffin Bay. The strait was named for the English explorer Jo ...

* Canada:

Anticosti Island ; moe, Notiskuan; mic, Natigostec , sobriquet = , image_name = RiviereHuileAnticosti.jpg , image_caption = Salmon fisherman on Rivière à l'Huile , image_map ...

Laurentian Channel The Laurentian Channel is a deep submarine valley off the coast of eastern Canada in the Gulf of Saint Lawrence. The channel is of glacial origin and is the submerged valley of the historic Saint Lawrence River, running from a sharp escarpment ...

Magdalen Islands The Magdalen Islands (french: Îles de la Madeleine ) are a small archipelago in the Gulf of Saint Lawrence with a land area of . While part of the Province of Quebec, the islands are in fact closer to the Maritime provinces and Newfoundland th ...

Prince Edward Island Prince Edward Island (PEI; ) is one of the thirteen Provinces and territories of Canada, provinces and territories of Canada. It is the smallest province in terms of land area and population, but the most densely populated. The island has seve ...

Newfoundland Newfoundland and Labrador (; french: Terre-Neuve-et-Labrador; frequently abbreviated as NL) is the easternmost province of Canada, in the country's Atlantic region. The province comprises the island of Newfoundland and the continental region ...

Strait of Belle Isle The Strait of Belle Isle (; french: Détroit de Belle Isle ) is a waterway in eastern Canada that separates the Labrador Peninsula from the island of Newfoundland, in the province of Newfoundland and Labrador. Location The strait is the northern o ...

. * USA: area between

Cape Hatteras Cape Hatteras is a cape located at a pronounced bend in Hatteras Island, one of the barrier islands of North Carolina. Long stretches of beach, sand dunes, marshes, and maritime forests create a unique environment where wind and waves shape ...

(

North Carolina North Carolina () is a state in the Southeastern region of the United States. The state is the 28th largest and 9th-most populous of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, Georgia and So ...

, USA) and Newfoundland island; from the

Gulf of Alaska The Gulf of Alaska (Tlingit: ''Yéil T'ooch’'') is an arm of the Pacific Ocean defined by the curve of the southern coast of Alaska, stretching from the Alaska Peninsula and Kodiak Island in the west to the Alexander Archipelago in the east, ...

to Friday Harbor,

Washington state Washington (), officially the State of Washington, is a state in the Pacific Northwest region of the Western United States. Named for George Washington—the first U.S. president—the state was formed from the western part of the Washington ...

* Russia:

White Sea The White Sea (russian: Белое море, ''Béloye móre''; Karelian and fi, Vienanmeri, lit. Dvina Sea; yrk, Сэрако ямʼ, ''Serako yam'') is a southern inlet of the Barents Sea located on the northwest coast of Russia. It is su ...

and

Novaya Zemlya Novaya Zemlya (, also , ; rus, Но́вая Земля́, p=ˈnovəjə zʲɪmˈlʲa, ) is an archipelago in northern Russia. It is situated in the Arctic Ocean, in the extreme northeast of Europe, with Cape Flissingsky, on the northern island, ...

Sea of Okhotsk The Sea of Okhotsk ( rus, Охо́тское мо́ре, Ohótskoye móre ; ja, オホーツク海, Ohōtsuku-kai) is a marginal sea of the western Pacific Ocean. It is located between Russia's Kamchatka Peninsula on the east, the Kuril Islands ...

Sea of Japan The Sea of Japan is the marginal sea between the Japanese archipelago, Sakhalin, the Korean Peninsula, and the mainland of the Russian Far East. The Japanese archipelago separates the sea from the Pacific Ocean. Like the Mediterranean Sea, it h ...

Bering Sea The Bering Sea (, ; rus, Бе́рингово мо́ре, r=Béringovo móre) is a marginal sea of the Northern Pacific Ocean. It forms, along with the Bering Strait, the divide between the two largest landmasses on Earth: Eurasia and The Ameri ...

Chukchi Sea Chukchi Sea ( rus, Чуко́тское мо́ре, r=Chukotskoye more, p=tɕʊˈkotskəjə ˈmorʲɪ), sometimes referred to as the Chuuk Sea, Chukotsk Sea or the Sea of Chukotsk, is a marginal sea of the Arctic Ocean. It is bounded on the west b ...

Kurile Islands The Kuril Islands or Kurile Islands (; rus, Кури́льские острова́, r=Kuril'skiye ostrova, p=kʊˈrʲilʲskʲɪjə ɐstrɐˈva; Japanese: or ) are a volcanic archipelago currently administered as part of Sakhalin Oblast in the ...

Commander Islands The Commander Islands, Komandorski Islands, or Komandorskie Islands (russian: Командо́рские острова́, ''Komandorskiye ostrova'') are a series of treeless, sparsely populated Russian islands in the Bering Sea located about ea ...

* Japan: off

Kasumi, Hyōgo was a town located in Kinosaki District, Hyōgo, Japan. As of 2003, the town had an estimated population of 13,519 and a density of 98.49 persons per km2. The total area was 137.26 km2. On April 1, 2005, Kasumi, along with the towns of M ...

Description

''Limacina helicina'' has wing-like

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

which evolved from the original gastropod foot (as is the case in all other pteropods). In this species, the color of the soft parts is dark

purple Purple is any of a variety of colors with hue between red and blue. In the RGB color model used in computer and television screens, purples are produced by mixing red and blue light. In the RYB color model historically used by painters, pu ...

violet Violet may refer to: Common meanings * Violet (color), a spectral color with wavelengths shorter than blue * One of a list of plants known as violet, particularly: ** ''Viola'' (plant), a genus of flowering plants Places United States * Viol ...

, with paler pellucid (translucent) parapodia. Sars G. O. (1878). ''Bidrag til kundskaben om norges arktiske fauna. I. Mollusca regonis arcticae Norwegiae. Oversigt over de i norges arktiske region forekommende bløddyr''. Christiania, Brøgger
pages 328-329Plate 29
figure 1
Plate 16
figure 17. The

shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses ** Thin-shell structure Science Biology * Seashell, a hard o ...

is sinistral, subglobose, subdiscoidal,

hyaline A hyaline substance is one with a glassy appearance. The word is derived from el, ὑάλινος, translit=hyálinos, lit=transparent, and el, ὕαλος, translit=hýalos, lit=crystal, glass, label=none. Histopathology Hyaline cartilage is ...

and very thin. The

spire A spire is a tall, slender, pointed structure on top of a roof of a building or tower, especially at the summit of church steeples. A spire may have a square, circular, or polygonal plan, with a roughly conical or pyramidal shape. Spires are ...

is depressed but it can be considered rather high in comparison of other ''Limacina'' species. The shell has 5-6 transversally striated

whorls A whorl ( or ) is an individual circle, oval, volution or equivalent in a whorled pattern, which consists of a spiral or multiple concentric objects (including circles, ovals and arcs). Whorls in nature File:Photograph and axial plane floral ...

. The suture is distinct. The

last whorl The body whorl is part of the morphology (biology), morphology of the gastropod shell, shell in those gastropod mollusks that possess a coiled shell. The term is also sometimes used in a similar way to describe the shell of a cephalopod mollusk ...

is large and with very obscure keel next to its umbilicus. The shell has a wide umbilicus. The aperture is higher than it is wide. The width of the shell is 5–10 mm or up to 13 mm. The height of the shell is up to 6 mm (when maximum width was 8 mm).Spoel S. van der (1972)
"Pteropoda Thecosomata"
''Zooplankton'', Conseil International Pour L’Exploration de la Mer, sheet 140-142. Limacina helicina operculum

Adult specimens in the genus ''Limacina'' have usually lost the operculum. The

radula The radula (, ; plural radulae or radulas) is an anatomical structure used by molluscs for feeding, sometimes compared to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food ...

consist of 10 rows. Each row consist of one central tooth and two lateral teeth. The

Digestive system The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver, and gallbladder). Digestion involves the breakdown of food into smaller and smaller compone ...

also includes an esophagus, gizzard sac and gut.

Ecology

Habitat

Pteropods are strict

mollusks that are highly adapted to life in the

open ocean The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or wa ...

. They are actively swimming in the water. ''Limacina helicina'' is a

holoplankton Holoplankton are organisms that are planktic (they live in the water column and cannot swim against a current) for their entire life cycle. Holoplankton can be contrasted with meroplankton, which are planktic organisms that spend part of their lif ...

ic species. Habitat of ''Limacina helicina'' is upper

epipelagic The photic zone, euphotic zone, epipelagic zone, or sunlight zone is the uppermost layer of a body of water that receives sunlight, allowing phytoplankton to perform photosynthesis. It undergoes a series of physical, chemical, and biological proc ...

and

glacial A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betw ...

. It lives in temperatures from -0.4 °C to +4.0 °C or rarely up to 7 °C. Vertical distribution is affected by the size and also by other factors. ''Limacina helicina'' of the size from 0.2 to 0.4 mm lives mainly in depths from 0 m to 50 m. Larger pteropods lives from 0 m to 150 m. For example, Gilmer & Harbison (1991) have found larger specimen of ''Limacina helicina'' to occur mainly in depths 5–25 m with abundance up to 2.5 adults in m³. They do not occur much in upper 4 m probably because of turbulence. Already Constantine John Phipps mentioned its "innumerable quantities" in arctic seas in 1774. ''Limacina helicina'' is a major component of the polar

zooplankton Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...

. It can comprise >50% of total zooplankton abundance (number of individuals per unit volume). Species of the clade

produce a fragile external calcium carbonate shell, which could serve as a

ballast Ballast is material that is used to provide stability to a vehicle or structure. Ballast, other than cargo, may be placed in a vehicle, often a ship or the gondola of a balloon or airship, to provide stability. A compartment within a boat, ship, ...

enabling large vertical migrations and as a protection against predators. The

aragonitic Aragonite is a carbonate mineral, one of the three most common naturally occurring crystal forms of calcium carbonate, (the other forms being the minerals calcite and vaterite). It is formed by biological and physical processes, including pre ...

composition of the shell makes it very sensitive to dissolution.

Aragonite Aragonite is a carbonate mineral, one of the three most common naturally occurring crystal forms of calcium carbonate, (the other forms being the minerals calcite and vaterite). It is formed by biological and physical processes, including prec ...

is a metastable form of calcium carbonate and it is more soluble in seawater than

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

. Because of its highly soluble aragonite shell and polar distribution, ''Limacina helicina'' may be one of the first organisms affected by

ocean acidification Ocean acidification is the reduction in the pH value of the Earth’s ocean. Between 1751 and 2021, the average pH value of the ocean surface has decreased from approximately 8.25 to 8.14. The root cause of ocean acidification is carbon dioxid ...

, and it is therefore a key

indicator species A bioindicator is any species (an indicator species) or group of species whose function, population, or status can reveal the qualitative status of the environment. The most common indicator species are animals. For example, copepods and other sma ...

of this process. As a key indicator of the acidification process, and a major component of polar ecosystems, ''Limacina helicina'' has become a focus for acidification research. Based on laboratory experiments, they are able to precipitate calcium carbonate at low aragonite saturation state. ''Limacina helicina'' seems to be relatively more resilient to elevated concentration of

carbon dioxide Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...

(CO₂) than other aragonitic organisms such as

coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and sec ...

s. Laboratory experiments results support the current concern for the future of Arctic pteropods, as the production of their shell appears to be very sensitive to decreased pH. A decline of pteropod populations would likely cause dramatic changes to various pelagic ecosystems. However, in response to acute abiotic stress, ''Limacina helicina'' shows high transcriptomic

plasticity Plasticity may refer to: Science * Plasticity (physics), in engineering and physics, the propensity of a solid material to undergo permanent deformation under load * Neuroplasticity, in neuroscience, how entire brain structures, and the brain it ...

, suggesting this species may have a limited capacity to acclimate to the effects of ocean acidification and ocean warming. Shelled pteropods also play a geochemical role in

carbon cycle The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and Earth's atmosphere, atmosphere of the Earth. Carbon is the main component of biological compounds as well as ...

in the oceans, as they contribute to the export of calcium carbonate and can represent a major component of the carbon transport to the

deep ocean The deep sea is broadly defined as the ocean depth where light begins to fade, at an approximate depth of 200 metres (656 feet) or the point of transition from continental shelves to continental slopes. Conditions within the deep sea are a combin ...

. Researchers found 24-53% individuals of ''Limacina helicina'' with shells damaged by dissolution off the U.S. West Coast in 2011.

Feeding habits

They produce large mucus webs to filter-feed on phytoplankton but also small zooplankton. They eat the web with the captured prey and then re-reproduce a web net. The web is large and spherical and it is difficult to see during the day because of

diffuse reflection Diffuse reflection is the reflection (physics), reflection of light or other radiation, waves or particles from a surface such that a ray (optics), ray incident on the surface is scattering, scattered at many angles rather than at just one angle ...

. Webs are easier to see at night. ''Limacina helicina'' is easily disturbed (like all other

); when disturbed, it retracts into its shell and destroys its web. Gilmer & Harbison (1991) have assumed, that ''Limacina helicina'' feeds while motionless (without actively swimming). Its web enables them

neutral buoyancy Neutral buoyancy occurs when an object's average density is equal to the density of the fluid in which it is immersed, resulting in the buoyant force balancing the force of gravity that would otherwise cause the object to sink (if the body's dens ...

or allow them slow sinking only. ''Limacina helicina'' plays a significant ecological role as a

phytoplankton Phytoplankton () are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater ecosystems. The name comes from the Greek words (), meaning 'plant', and (), meaning 'wanderer' or 'drifter'. Ph ...

grazer. ''Limacina helicina'' is obligate ciliary feeder. Gilmer & Harbison (1991) hypothesized that ''Limacina helicina'' are "web trappers", who are also chemically attracting its motile prey. Major parts of the food of ''Limacina helicina'' include

tintinnid Tintinnids are ciliates of the choreotrich order Tintinnida, distinguished by vase-shaped shells, the name deriving from a Latin source meaning a small tinkling bell, that are called'' loricae'', which are mostly protein but may incorporate min ...

(Tintinnida), small crustaceans -

copepod Copepods (; meaning "oar-feet") are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (inhabiting sea waters), some are benthos, benthic (living on the ocean floor) ...

s (Copepoda) and juvenile specimen of its own species (

cannibalism Cannibalism is the act of consuming another individual of the same species as food. Cannibalism is a common ecological interaction in the animal kingdom and has been recorded in more than 1,500 species. Human cannibalism is well documented, b ...

). Danish zoologist Johan Erik Vesti Boas reported

diatom A diatom (Neo-Latin ''diatoma''), "a cutting through, a severance", from el, διάτομος, diátomos, "cut in half, divided equally" from el, διατέμνω, diatémno, "to cut in twain". is any member of a large group comprising sev ...

s (Bacillariophyceae),

dinoflagellate The dinoflagellates (Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates are ...

s (Dinoflagellata) and tintinnids in the

digestive system The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver, and gallbladder). Digestion involves the breakdown of food into smaller and smaller compone ...

of ''Limacina helicina'' in 1888 already. Diatoms and dinoflagellates appear to pass the digestive system of adults largely intact.

Fecal pellet Feces ( or faeces), known colloquially and in slang as poo and poop, are the solid or semi-solid remains of food that was not digested in the small intestine, and has been broken down by bacteria in the large intestine. Feces contain a relati ...

s of ''Limacina helicina'' contains small cells, dinoflagellates and diatoms as main largely intact food items and also few small fragments of tintinnids, ''Limacina'' and copepods. All experiments performed on ''Limacina helicina'' in the laboratory were done on starved specimens, because they do not feed in unnatural conditions.

Ocean acidification Ocean acidification is the reduction in the pH value of the Earth’s ocean. Between 1751 and 2021, the average pH value of the ocean surface has decreased from approximately 8.25 to 8.14. The root cause of ocean acidification is carbon dioxid ...

and ocean warming may cause ''Limacina helicina'' to increase its metabolic rate and use more storage compounds, especially during the Arctic winter when food is limited. This may result in a decline in reproductive success and survival. Gilmer & Harbison (1991) also suggested that smaller specimens may be

herbivore A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...

s feeding preferentially on

and

protozoan Protozoa (singular: protozoan or protozoon; alternative plural: protozoans) are a group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic tissues and debris. Histo ...

s and that larger specimens became omnivores.

Life cycle

''Limacina helicina'' is a

protandric hermaphrodite In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes. Many taxonomic groups of animals (mostly invertebrates) do not have sepa ...

. Males are smaller, at sizes of 4–5 mm and then they change to females, which are larger than 5 mm. Sperm is transferred by

spermatophore A spermatophore or sperm ampulla is a capsule or mass containing spermatozoa created by males of various animal species, especially salamanders and arthropods, and transferred in entirety to the female's ovipore during reproduction. Spermatophores ...

s during copulation. They lay eggs in ribbon-like clusters mainly in summer, but also a little in winter. The size of the

veliger A veliger is the planktonic larva of many kinds of sea snails and freshwater snails, as well as most bivalve molluscs (clams) and tusk shells. Description The veliger is the characteristic larva of the gastropod, bivalve and scaphopod ...

larvae is about 0.15 mm.Hopcroft R. (created 31 January 2009)
"Sea Butterfly: ''Limacina helicina'' (Phipps, 1774)"
Arctic Ocean biodiversity, accessed 30 January 2011. When animals reached 0.7 mm in size,

gonad A gonad, sex gland, or reproductive gland is a mixed gland that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. The male gonad, the testicle, produces sper ...

s have been detected in them. Fully mature individuals are 0.8 mm in size. The life cycle of ''Limacina helicina'' lasts about 1 year or 1.5–2 years.

Predators

''Limacina helicina'' plays an important role in the marine

food web A food web is the natural interconnection of food chains and a graphical representation of what-eats-what in an ecological community. Another name for food web is consumer-resource system. Ecologists can broadly lump all life forms into one ...

as a major dietary component for predators such as large

herring Herring are forage fish, mostly belonging to the family of Clupeidae. Herring often move in large schools around fishing banks and near the coast, found particularly in shallow, temperate waters of the North Pacific and North Atlantic Oceans, i ...

''Clupea'' sp.,Wing B. (not dated)
"Auke Bay Laboratory (ABL). Ocean Carrying Capacity Program. Unusual Observations of Fish and Invertebrates From the Gulf of Alaska, 2004-05"
accessed 29 January 2011.

chum salmon The chum salmon (''Oncorhynchus keta''), also known as dog salmon or keta salmon, is a species of anadromous salmonid fish from the genus '' Oncorhynchus'' (Pacific salmon) native to the coastal rivers of the North Pacific and the Beringian A ...

''Oncorhynchus keta'',

pink salmon Pink salmon or humpback salmon (''Oncorhynchus gorbuscha'') is a species of anadromous fish in the salmon family. It is the smallest and most abundant of the Pacific salmon. The scientific species name is based on the Russian common name for ...

''Oncorhynchus gorbuscha'',

rorqual Rorquals () are the largest group of baleen whales, which comprise the family Balaenopteridae, containing ten extant species in three genera. They include the largest animal that has ever lived, the blue whale, which can reach , and the fin wha ...

s,"''Limacina helicina helicina helicina''"
Marine Species Identification Portal, accessed 8 February 2011. '' Phoca hispida'' and other

seals Seals may refer to: * Pinniped, a diverse group of semi-aquatic marine mammals, many of which are commonly called seals, particularly: ** Earless seal, or "true seal" ** Fur seal * Seal (emblem), a device to impress an emblem, used as a means of a ...

and birds. The pteropod ''

Clione limacina ''Clione limacina'', known as the naked sea butterfly, sea angel, and common clione, is a sea angel (pelagic sea slug) found from the surface to greater than depth.Gofas, S. (2012). ''Clione limacina''. Accessed through: World Register of Marine ...

'' feeds almost entirely on the genus ''Limacina'': on ''Limacina helicina'' and on ''

Limacina retroversa ''Limacina retroversa'' is a species of swimming predatory sea snail in the family Limacinidae, that belongs to the group commonly known as sea butterflies (Thecosomata). There is one subspecies, ''Limacina retroversa australis'' (Eydoux & Sou ...

''.Lalli C. M. & Gilmer R. W. (1989). ''Pelagic Snails. The biology of holoplanktonic gastropod molluscs.'' Stanford University Press: Stanford, California
page 185188
Also the pteropod ''

Paedoclione doliiformis ''Paedoclione doliiformis'' is a species of sea angel, a small floating sea slug, a pelagic marine gastropod mollusk in the family Clionidae. ''Paedoclione doliiformis'' is the only species in the genus ''Paedoclione''.

Locomotion

''Limacina helicina'' possesses a pair of flexible, wing-like appendages called parapodia which it beats in a complex 3D stroke pattern which resembles the

wing A wing is a type of fin that produces lift while moving through air or some other fluid. Accordingly, wings have streamlined cross-sections that are subject to aerodynamic forces and act as airfoils. A wing's aerodynamic efficiency is expres ...

kinematics of

flying insects The Pterygota ( grc, πτερυγωτός, pterugōtós, winged) are a subclass of insects that includes the winged insects. It also includes insect orders that are secondarily wingless (that is, insect groups whose ancestors once had wings b ...

. By doing so, the animal effectively flies through the water. The sea butterfly uses a high angle of attack of approximately 45-50 degrees to generate lift, and it beats its wings 4 to 10 times per second. It propels itself using a version of the clap and fling mechanism described by

Torkel Weis-Fogh Torkel Weis-Fogh (25 March 1922 – 13 November 1975) was a Danish zoologist and Professor at the University of Cambridge and the University of Copenhagen. He is best known for his contributions to the understanding of insect flight, especially ...

in small insects such as

thrips Thrips ( order Thysanoptera) are minute (mostly long or less), slender insects with fringed wings and unique asymmetrical mouthparts. Different thrips species feed mostly on plants by puncturing and sucking up the contents, although a few are ...

. Another aspect of locomotion by ''Limacina helicina'' is the extreme, forward-back pitching (called hyper-pitching) which it experiences during each half-stroke of its wings. The animal rocks forward and backward by up to 60 degrees during each half-stroke. No other species is known to experience such extreme hyper-pitching during normal locomotion.

References

This article incorporates CC-BY-2.5 text from the reference and public domain text from the reference Tryon G. W. (1873). ''American marine conchology: or, Descriptions of the shells of the Atlantic coast of the United States from Maine to Florida''. Philadelphia
page 121
122
plate 14
figure 253.

External links

distribution map
at Marine Species Identification Portal {{taxonbar, from=Q3023651 Gastropods described in 1774 Fauna of the Arctic Ocean Limacinidae Taxa named by Constantine Phipps, 2nd Baron Mulgrave