''Nassarius distortus'', common name : the distorted nassa, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

sea snail Sea snails are slow-moving marine (ocean), marine gastropod Mollusca, molluscs, usually with visible external shells, such as whelk or abalone. They share the Taxonomic classification, taxonomic class Gastropoda with slugs, which are distinguishe ...

, a marine

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

mollusc Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Nassariidae The Nassariidae, Nassa mud snails (US), or dog whelks (UK) are a taxonomic family of small to medium-sized snails, mostly marine gastropod mollusks in the clade Neogastropoda. These snails have rounded shells with a high spire, an oval ap ...

, the Nassa mud snails or dog whelks.

Description

The shell size varies between 18 mm and 35 mm The ovate, conical shell is smooth, polished, and whitish. A decurrent band of a rose color is seen beneath the suture, and three others surround the middle of the lowest

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). In nature File:Photograph and axial plane floral diagra ...

. That of the middle is broader and more apparent. 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. Spire ...

is composed of seven slightly convex whorls, ornamented with longitudinal ribs formed like folds, numerous and slightly elevated. The upper edge of the whorls is a little flattened. The base of the lowest is accompanied with two distinct ridges. The suture is edged with rounded tubercles situated between each fold, where they form a sort of necklace. The white

aperture In optics, the aperture of an optical system (including a system consisting of a single lens) is the hole or opening that primarily limits light propagated through the system. More specifically, the entrance pupil as the front side image o ...

is ovate, contracted above by a transverse fold of the callosity. The outer

lip The lips are a horizontal pair of soft appendages attached to the jaws and are the most visible part of the mouth of many animals, including humans. Mammal lips are soft, movable and serve to facilitate the ingestion of food (e.g. sucklin ...

is subtruncated, somewhat denticulated upon the lower edge, and marked with transverse striae internally. The

columella Lucius Junius Moderatus Columella (, Arabic: ) was a prominent Roman writer on agriculture in the Roman Empire. His in twelve volumes has been completely preserved and forms an important source on Roman agriculture and ancient Roman cuisin ...

edge is covered by a pretty thick callosity, spreading a little upon the belly of the shell.Kiener (1840). General species and iconography of recent shells : comprising the Massena Museum, the collection of Lamarck, the collection of the Museum of Natural History, and the recent discoveries of travellers; Boston :W.D. Ticknor,1837
(described as ''Buccinum monile'')

Distribution

This marine species has a wide distribution in the Indo-West Pacific; also occurs off Australia (

Queensland Queensland ( , commonly abbreviated as Qld) is a States and territories of Australia, state in northeastern Australia, and is the second-largest and third-most populous state in Australia. It is bordered by the Northern Territory, South Austr ...

)

References

* Adams, A. 1852. ''Catalogue of the species of Nassa, a genus of Gasteropodous Mollusca, belonging to the family Buccinidae, in the Collection of Hugh Cuming, Esq., with the description of some new species.'' Proceedings of the Zoological Society of London 1851(19): 94–112 * Reeve, L.A. 1853. ''Monograph of the genus Nassa.'' pls 1–25 in Reeve, L.A. (ed). Conchologia Iconica. London : L. Reeve Vol. 8. * Dautzenberg, Ph. (1929). ''Mollusques testacés marins de Madagascar''. Faune des Colonies Francaises, Tome III * Cernohorsky W. O. (1984). ''Systematics of the family Nassariidae (Mollusca: Gastropoda).'' Bulletin of the Auckland Institute and Museum 14: 1–356 * Wilson, B. 1994. ''Australian Marine Shells. Prosobranch Gastropods''. Kallaroo, WA : Odyssey Publishing Vol. 2 370 pp.

External links

* {{Taxonbar, from=Q6967449 distortus Gastropods described in 1852