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 ...
, a marine
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 ...
South Orkney Islands
The South Orkney Islands are a group of islands in the Southern Ocean, about north-east of the tip of the Antarctic PeninsulaSouth Shetland Islands, the
Antarctic Peninsula
The Antarctic Peninsula, known as O'Higgins Land in Chile and Tierra de San Martín in Argentina, and originally as Graham Land in the United Kingdom and the Palmer Peninsula in the United States, is the northernmost part of mainland Antarctic ...
It is orange-yellow, with two pairs of cephalic tentacles with large black eyes.
The shell is small, and wider than it is high.Bouchet, P. (2010). ''Margarella whiteana'' Linse, 2002. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=197259 on 2011-03-17
The orbicular, deeply umbilicated shell has an obtuse-conical shape. It contains four convex
whorl
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 ...
s, the last of which is adorned only by growth lines. The oblique aperture is sub-circular and pearly inside. In, adults its edges are joined by a callus . The operculum is polygyrous spiral. The color of the shell is bluish gray or greenish.Charcot, Lamy et al. (1906), Expédition antarctique française (1903–1905) fasc. 3 (1906) /ref> The maximum recorded shell length is 12.5 mm.Welch J. J. (2010). "The "Island Rule" and Deep-Sea Gastropods: Re-Examining the Evidence". '' PLoS ONE'' 5(1): e8776. .
Habitat
Minimum recorded depth is 0 m. Maximum recorded depth is 24 m.
References
* Zelaya D.G. (2004) ''The genus Margarella Thiele, 1893 (Gastropoda: Trochidae) in the southwestern Atlantic Ocean''. The Nautilus 118(3): 112–120
* Engl W. (2012) ''Shells of Antarctica''. Hackenheim: Conchbooks. 402 pp