''Oenopota violacea'' 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

It is extremely difficult to characterise this species, because both its form and

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 ...

are more variable than in any other of the whole genus. Sometimes the form is oval, with 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 ...

about the same length as the

aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. An opt ...

, and sometimes it is fusiform, witli a long, strongly acuminate spire. The

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 are sometimes angulated and sometimes cylindrically rounded. The sculpture is, often, by far the most prominent in the axial direction, and often, it is so transversally. The typical shell has, thus, very prominent spiral ribs devoid of other sculpture than lines of growth, whilst the varieties ''violacea'' and ''cylindracea'', frequently, have quite prominent axial ribs, and these are invariably – even if they only occur as lines of growth – curved. The most characteristic feature is the, not very long, cauda, and the deep wide

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 apex gives no assistance as a specific feature, because it varies according to the sculptural character of the shell. The shell of the variety ''gemminolineata'' is fusiform. The spire is strongly acuminate, and longer than the aperture. The axial sculpture consists of, only faint lines of growth, whilst the spiral sculpture consists of lines occurring in pairs. In the penultimate whorl there are 4 pairs of such lines.Friele H., 1877: Preliminary report on the Mollusca from the Norwegian North Atlantic Expedition in 1876; Nyt Magazin for Naturvidenskaberne 23: 1–10, 1 pl.

Distribution

This species occurs in Northeast Atlantic Ocean and off the

British Isles The British Isles are a group of islands in the North Atlantic Ocean off the north-western coast of continental Europe, consisting of the islands of Great Britain, Ireland, the Isle of Man, the Inner and Outer Hebrides, the Northern Isles, ...

at depths between 80 m and 505 m

References

* 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 * Sysoev A.V. (2014). ''Deep-sea fauna of European seas: An annotated species check-list of benthic invertebrates living deeper than 2000 m in the seas bordering Europe. Gastropoda''. Invertebrate Zoology. Vol.11. No.1: 134–155

External links

Friele H., 1877: Preliminary report on the Mollusca from the Norwegian North Atlantic Expedition in 1876; Nyt Magazin for Naturvidenskaberne 23: 1–10, 1 pl.
* * {{DEFAULTSORT:Oenopota Violacea violacea Gastropods described in 1842