''Oenopota casentina'' is a species of

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 ...

mollusk 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 e ...

in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Mangeliidae Mangeliidae is a monophyletic family of small to medium-sized, predatory sea snails, marine gastropod mollusks in the superfamily Conoidea. Bouchet, P. (2011). Mangeliidae P. Fischer, 1883. In: MolluscaBase (2016). Accessed through: World Regis ...

Description

The length of the shell varies between 8 mm and 13 mm, its diameter 5 mm. (Original description) The small, white shell contains about five

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

protoconch A protoconch (meaning first or earliest or original shell) is an embryonic or larval shell which occurs in some classes of molluscs, e.g., the initial chamber of an ammonite or the larval shell of a gastropod. In older texts it is also called ...

decorticated. The whorls show a subangular shoulder in front of the anal fasciole. The axial

sculpture Sculpture is the branch of the visual arts that operates in three dimensions. Sculpture is the three-dimensional art work which is physically presented in the dimensions of height, width and depth. It is one of the plastic arts. Durable sc ...

consists of (on the penultimate whorl about 20) low, threadlike ribs extending from the shoulder to the succeeding suture, but more or less obsolete on the

body whorl The body whorl is part of the morphology of the 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. In gastropods In gastropods, the b ...

. The spiral sculpture consists of faint feeble striae on the fasciole. In front of the shoulder are numerous close-set flattish small threads, extending uniformly to the

siphonal canal The siphonal canal is an anatomical feature of the shells of certain groups of sea snails within the clade Neogastropoda. Some sea marine gastropods have a soft tubular anterior extension of the mantle called a siphon through which water is ...

. The

anal sulcus The anal sulcus, also called the anal sinus or anal canal, in Gastropods is a notch, a shelly tube at the top of the aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and fo ...

is shallow. The outer lip is slightly arcuate, the inner lip is erased. The columella is short, and straight. The siphonal canal is hardly differentiated.Dall (1919) Descriptions of new species of Mollusca from the North Pacific Ocean; Proceedings of the U.S. National Museum, vol. 56 (1920)

Distribution

This species was found in the

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 ...

, north of Unalaska.

References

External links

* * {{DEFAULTSORT:Oenopota Casentina casentina Gastropods described in 1919