''Oenopota granitica'' 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 ...

.Dall (1919) Descriptions of new species of Mollusca from the North Pacific Ocean; Proceedings of the U.S. National Museum, vol. 56 (1920)

Description

The length of the shell attains 13 mm, its diameter 5 mm. (Original description) The small shell is waxen white, darker on the columella. The protoconch has 2

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 followed by about five subsequent whorls. The protoconch is flat-topped, the first whorl with one strong keel, the second with three. The suture is laid on the anterior keel, which is smaller, and in the subsequent whorls the suture is not appressed but distinct. The spiral

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 first two whorls a strong peripheral cord and one thread at the suture, on the third whorl three threads in front of the cord, on the remainder four. 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 peripheral cord is not prominent but from the anal

fasciole A fasciole in mollusks refers to a band or ribbon-like structure that is often seen as a flattened, slightly depressed area on the shell, formed by the successive growth lines on the edges of a canal. It is typically found on the surface of the she ...

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 ...

are about 16 strong threads with wider interspaces and an occasional intercalary smaller thread. They do not nodulate when they cross the ribs. On the siphonal canal are numerous small close-set threads. The anal fasciole is without spiral sculpture. The axial sculpture consists of (on the body whorl 13) strong rounded ribs not continuous up 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 ...

and obsolete on the base but prominent and arcuate over the fasciole. reaching the preceding suture which they undulate. 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 ...

is rather narrow. The anal fasciole at the suture, is shallow and wide. The thin outer lip is moderately produced. The inner lip is smooth and erased. The columella is short, straight, attenuated in front. The siphonal canal is short but distinct.

Distribution

This marine species occurs off

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S., ...

, found at Port Althorp.

References

External links

* * {{DEFAULTSORT:Oenopota Granitica granitica Gastropods described in 1919