''Limacina rangii'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of swimming

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 ...

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 ...

,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=719583 on 2015-01-24 which belong to the group 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 ...

(

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 ...

). ''Limacina rangii'' is a

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

of the

mesozooplankton Zooplankton are the heterotrophic component of the planktonic community (the " zoo-" prefix comes from ), having to consume other organisms to thrive. Plankton are aquatic organisms that are unable to swim effectively against currents. Consequent ...

Antarctic The Antarctic (, ; commonly ) is the polar regions of Earth, polar region of Earth that surrounds the South Pole, lying within the Antarctic Circle. It is antipodes, diametrically opposite of the Arctic region around the North Pole. The Antar ...

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 ...

ecosystems. Until 2010 this taxon was known only as ''Limacina helicina antarctica'' or as ''Limacina helicina'' f. ''antarctica''. ''Limacina rangii'' is however now considered to be a separate species from ''

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 ...

'', based on

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 is encoded by the ''MT-CO1'' gene in eukaryotes. The gene is also called ''COX1'', ''CO1'', or ''COI''. Cytochrome c oxidase ...

(COI) gene sequences. Limacina antarctica 2

Distribution

The distribution of ''Limacina rangii'' is circumglobal south of 50°S. This species occurs in the

Weddell Sea The Weddell Sea is part of the Southern Ocean and contains the Weddell Gyre. Its land boundaries are defined by the bay formed from the coasts of Coats Land and the Antarctic Peninsula. The easternmost point is Cape Norvegia at Princess Martha C ...

and

Ross Sea The Ross Sea is a deep bay of the Southern Ocean in Antarctica, between Victoria Land and Marie Byrd Land and within the Ross Embayment, and is the southernmost sea on Earth. It derives its name from the British explorer James Clark Ross who ...

in the

and in

Cumberland Bay Cumberland Bay is a bay, wide at its entrance between Larsen Point and Barff Point, which separates into two extensive arms, Cumberland West Bay and Cumberland East Bay, which recede inland along the northern coast of South Georgia. It w ...

South Georgia South Georgia is an island in the Atlantic Ocean, South Atlantic Ocean that is part of the British Overseas Territories, British Overseas Territory of South Georgia and the South Sandwich Islands. It lies around east of the Falkland Islands. ...

. and other localities in the

Southern Ocean The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the world ocean, generally taken to be south of 60th parallel south, 60° S latitude and encircling Antarctica. With a size of , it is the seco ...

Description

''Limacina rangii'' has a sinistral and very thin shell. The shell thickness is approximately 2–9 μm. There are ribs on the surface of the shell. There are differences in the shell structure between ''Limacina rangii'' and ''

''. The width of the shell is 0.5–6 mm.

Ecology

''Limacina rangii'' 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 l ...

ic species. It is very abundant in the Southern Ocean, with up to 2681 individuals per m³. This species is abundant in the

, Antarctica. It is sometimes even more abundant than

krill Krill ''(Euphausiids)'' (: krill) are small and exclusively marine crustaceans of the order (biology), order Euphausiacea, found in all of the world's oceans. The name "krill" comes from the Norwegian language, Norwegian word ', meaning "small ...

. ''Limacina rangii'' feeds mainly on

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

and also on

zooplankton Zooplankton are the heterotrophic component of the planktonic community (the " zoo-" prefix comes from ), having to consume other organisms to thrive. Plankton are aquatic organisms that are unable to swim effectively against currents. Consequent ...

, but less so. It catches its prey using

mucus Mucus (, ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both Serous fluid, serous and muc ...

webs. This snail is a

primary consumer A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat no ...

and directly depends on phytoplankton. When the phytoplankton is reduced, the population of ''Limacina rangii'' is also reduced, and it can even disappear as happened in

McMurdo Sound The McMurdo Sound is a sound in Antarctica, known as the southernmost passable body of water in the world, located approximately from the South Pole. Captain James Clark Ross discovered the sound in February 1841 and named it after Lieutenant ...

in the summer of 2000–2001. It is considered an

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 the health of the ecosystem. Under different conditions in McMurdo Sound there can be over 300 individuals per m³, which is over 20% of the

biomass Biomass is a term used in several contexts: in the context of ecology it means living organisms, and in the context of bioenergy it means matter from recently living (but now dead) organisms. In the latter context, there are variations in how ...

Fecal pellet Feces (also known as faeces or fæces; : faex) 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 relatively small amount of ...

s of ''Limacina rangii'' and its quantity have been firstly described by Manno et al. (2010). Fecal pellets are oval, greenish brown and with

peritrophic membrane The peritrophic matrix (from the prefix ''peri-'', meaning around, and ''-trophic'', referring to nutrition(food)) or peritrophic membrane is a semi-permeable, non-cellular structure which surrounds the food bolus in an organism's midgut. Although ...

. A size of a single pellet varies from 103 μm (286600 μm³) to 120 μm (440,610 μm³). A single ''Limacina rangii'' produces about 6-11 pellets daily. Population of ''Limacina rangii'' in the studied area in the Ross Sea produced from about 71,000 pellets per square meter per year to about 362,000 pellets per square meter per year. Fecal pellets of ''Limacina rangii'' has contributed to about 19% of flux of

organic carbon Total organic carbon (TOC) is an analytical parameter representing the concentration of organic carbon in a sample. TOC determinations are made in a variety of application areas. For example, TOC may be used as a non-specific indicator of wa ...

. Fecal pellets of ''Limacina rangii'' together with dead ''Limacina rangii'' can cover up to 72% (estimation) of organic

carbon flux The carbon cycle is a part of the biogeochemical cycle where carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of Earth. Other major biogeochemical cycles include the nitrogen cycle and the water cycl ...

to the deep water. ''Limacina rangii'' probably affect

carbon cycle The carbon cycle is a part of the biogeochemical cycle where carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of Earth. Other major biogeochemical cycles include the nitrogen cycle and the water cycl ...

, resources of

and

dimethyl sulfide Dimethyl sulfide (DMS) or methylthiomethane is an organosulfur compound with the formula . It is the simplest thioether and has a characteristic disagreeable odor. It is a flammable liquid that boils at . It is a component of the smell produc ...

(emission by phytoplankton), that may have impact on the Earth's

climate Climate is the long-term weather pattern in a region, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteoro ...

. Many predators depend on ''Limacina rangii'' as their food source: * The gastropod ''

Clione antarctica ''Clione antarctica'' is a species of "sea angel", a sea slug, a pelagic marine (ocean), marine gastropod mollusk in the family Clionidae, the "sea angels". Distribution The distribution of ''Clione antarctica'' is within the Southern Hemisphe ...

'' feeds only on ''Limacina rangii''. There is a

coevolution In biology, coevolution occurs when two or more species reciprocally affect each other's evolution through the process of natural selection. The term sometimes is used for two traits in the same species affecting each other's evolution, as well a ...

ary relationship between this specialized predator and its prey; their life cycles are parallel. * The medusae '' Solmundella bitentaculata'' and '' Diplulmaris antarctica'' * Fish in the family Myctophidae heavily depend on ''Limacina rangii''. ''Limacina'' are food for a number of myctophid fishes in the Southern Ocean: '' Electrona antarctica'', ''

Electrona paucirastra ''Electrona paucirastra'', the belted lanternfish, is a lanternfish found around the globe in the southern hemisphere between 35° S and 48° S. It grows to a length of SL. It is a mesopelagic The mesopelagic zone (Greek language, Greek μ� ...

'', ''

Electrona subaspera ''Electrona subaspera'', also known as the rough lanternfish, is a marine, mesopelagic The mesopelagic zone (Greek language, Greek μέσον, middle), also known as the middle pelagic or twilight zone, is the part of the pelagic zone that lie ...

'', ''

Metelectrona herwigi ''Metelectrona'' is a genus of lanternfishes. Species There are currently three recognized species in this genus: * ''Metelectrona ahlstromi'' Wisner, 1963 * '' Metelectrona herwigi'' Hulley, 1981 (Herwig's lanternfish) * '' Metelectrona ventr ...

'', ''

Protomyctophum normani ''Protomyctophum normani'' is a species of lanternfish Lanternfish (or myctophids, from the Greek language, Greek μυκτήρ ''myktḗr'', "nose" and ''ophis'', "serpent") are small mesopelagic fish of the large family (biology), family Myc ...

'', ''

Diaphus taaningi ''Diaphus taaningi'', the slopewater lanternfish, is a species of lanternfish found in the eastern Atlantic Ocean. Description This species reaches a length of . Etymology The fish is named in honor of Danish lanternfish expert Åge Vedel Tåni ...

'', '' Diaphus hudsoni'', ''

Gymnoscopelus nicholsi ''Gymnoscopelus'' is a genus of lanternfishes. The name is from the Greek ''gymnos'', "naked" and ''skopelos'', "lanternfish." They can live in extremely cold water; two species, '' Gymnoscopelus nicholsi'' and '' Gymnoscopelus braueri'', have b ...

'', ''

Ceratoscopelus warmingii ''Ceratoscopelus'' is a genus of lanternfish. Species There are currently three recognized species in this genus: * ''Ceratoscopelus maderensis'' ( R. T. Lowe, 1839) (Madeira lanternfish) * ''Ceratoscopelus townsendi ''Ceratoscopelus'' is a ...

'' and ''

Symbolophorus boops ''Symbolophorus boops'' is a species of fish in the family Myctophidae. References Myctophidae Fish described in 1845 {{Myctophiformes-stub ...

''. * Also notothenioid fish (family

Nototheniidae : ''In some scientific literature, the term "cod icefish" is used to identify members of this family. This should not be confused with the term "icefish," which refers to the "white-blooded" fishes of the family Channichthyidae. See Icefish (disam ...

) heavily depend on ''Limacina rangii'' as food. For example, fishes: ''

Trematomus newnesi ''Trematomus'' is a genus of marine ray-finned fishes, belonging to the family Nototheniidae, the notothens or cod icefishes. These fishes occur in the Southern Ocean. Taxonomy ''Trematomus'' was first described as a genus in 1902 by the Belgian ...

'', '' Trematomus bernacchii'', '' Trematomus hansoni'', ''

Trematomus centronotus ''Trematomus'' is a genus of marine ray-finned fishes, belonging to the Family (biology), family Nototheniidae, the notothens or cod icefishes. These fishes occur in the Southern Ocean. Taxonomy ''Trematomus'' was first described as a genus in 1 ...

'' and '' Pagothenia borchgrevink''. *

Whales Whales are a widely distributed and diverse group of fully Aquatic animal, aquatic placental mammal, placental marine mammals. As an informal and Colloquialism, colloquial grouping, they correspond to large members of the infraorder Cetacea ...

heavily depend on this species

References

* Hunt B., Strugnell J., Bednarsek N., Linse K., Nelson R.J., Pakhomov E., Seibel B., Steinke D. & Würzberg L. (2010). ''Poles apart: The "bipolar" pteropod species Limacina helicina is genetically distinct between the Arctic and Antarctic Oceans.'' PLoS One 5(3):e9835

External links

Map of distribution of ''Limacina antarctica''
at Marine Species Identification Portal. {{Taxonbar, from=Q13762958 Limacinidae Gastropods described in 1854