''Alcithoe jaculoides'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of large

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 ...

mollusc 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 esti ...

in the family

Volutidae ''Volutidae'', common name volutes, are a taxonomic family of predatory sea snails that range in size from 9 mm to over 500 mm. They are marine gastropod mollusks. Most of the species have no operculum. Distribution This family of sea snails ...

, the volutes.

Description

The length of the shell attains 188 mm, its diameter 70 mm. (Described as ''Alcithoe calva'') The shell is very large, narrow, and elongated, comprising 8½

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 ...

has a scaphelloid shape. It is moderately large, consisting of 2½ smooth whorls. The remaining whorls are smooth and devoid of

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 ...

, except in rare instances where 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 ...

whorls are faintly shouldered, showing traces of axial ribs. The spire is tall with slightly convex whorls. It measures approximately half the height of 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 ...

, 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 ...

is elongate and sub-cylindrical, gradually contracted below to a rounded

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 ...

, not marked off by the usual ridge. The

is long and rather narrow with a shallow notch below. The outer

lip The lips are the visible body part at the mouth of many animals, including humans. Lips are soft, movable, and serve as the opening for food intake and in the articulation of sound and speech. Human lips are a tactile sensory organ, and can be ...

is thickened and reflexed above, ascending about one-third the height of the penultimate whorl. The

columella Lucius Junius Moderatus Columella (; Arabic: , 4 – ) was a prominent writer on agriculture in the Roman Empire. His ' in twelve volumes has been completely preserved and forms an important source on Roman agriculture, together with the wo ...

is straight, tapering to a sharp point below, with six comparatively weak, very oblique plications; the uppermost being more or less rudimentary. There is no projecting callus plate. The inner lip is spread as a thin glaze broadly over the body whorl. The color of the shell is pale buff, ornamented with indistinct, irregular light brown zigzag lines. The interior of the aperture is pinkish-fawn.

Distribution

This species is found only along the coast of

North Island The North Island, also officially named Te Ika-a-Māui, is one of the two main islands of New Zealand, separated from the larger but much less populous South Island by the Cook Strait. The island's area is , making it the world's 14th-largest ...

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

. Powell A. W. B. (1979). ''New Zealand Mollusca''. William Collins Publishers Ltd, Auckland, New Zealand, .

References

Sources

* * * * {{Taxonbar, from=Q3140496 jaculoides Gastropods of New Zealand Gastropods described in 1924