''Aesopus cassandra'' 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 ...

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 ...

Columbellidae The Columbellidae, the dove snails or dove shells, are a family of minute to small sea snails, marine gastropod mollusks in the order Neogastropoda.Bouchet, P.; Gofas, S. (2010). Columbellidae. In: Bouchet, P.; Gofas, S.; Rosenberg, G. (2010) Wo ...

, the dove snails.

Description

The length of the shell varies between 5 mm and 15 mm, its diameter between 1 mm and 6 mm. The shell is small, slender, tall, and moderately solid. Its color is white (possibly bleached). It comprises seven

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, including a two-whorled exserted

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 ...

, and is angled at the suture. The

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 ...

features small, sharp spiral threads, with three on the earlier whorls and about ten 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 ...

. Above, the threads are widely spaced, but they become crowded towards the base. The interstices are latticed by growth lines. 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 narrow and oblong, with a short

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 ...

.Hedley, C. (1904). Studies on Australian Mollusca. Part VIII. Proceedings of the Linnean Society of New South Wales. 29: 182–211, pls 8–10

Distribution

This marine species is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

and occurs off New South Wales, South Australia, Tasmania and Victoria.

References

* May, W.L. 1921. A Checklist of the Mollusca of Tasmania. Hobart, Tasmania : Government Printer 114 pp. * Cotton, B.C. 1957. Australian Recent and Tertiary Species of the Molluscan Family Pyrenidae. Adelaide : Privately published. {{Taxonbar, from=Q13231398 cassandra Gastropods described in 1904 Gastropods of Australia Endemic fauna of Australia