''Cratidentium ocellinum'', common name the eyelet top shell, is a

species In biology, a species is the basic unit of Taxonomy (biology), 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 ...

of sea snail, a

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...

gastropod

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 es ...

in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Trochidae The Trochidae, common name top-snails or top-shells, are a family of various sized sea snails, marine gastropod molluscs in the subclass Vetigastropoda. This family is commonly known as the top-snails because in many species the shell resembles ...

, the top snails.

Description

The size of the shell attains 4 mm. The small, solid, imperforate shell has a conical shape with a gradated

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 ...

with five

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 flo ...

s. It is prominently keeled at the periphery and again at the shoulder. Below the periphery the colour is uniform buff, above it broad, radial stripes of buff pink, alternate with white. Along the periphery are pairs of dashes of madder brown, sometimes these enclose a tinted space and have a background of opaque white, thus assuming an ocellated aspect. The

apex The apex is the highest point of something. The word may also refer to: Arts and media Fictional entities * Apex (comics), a teenaged super villainess in the Marvel Universe * Ape-X, a super-intelligent ape in the Squadron Supreme universe *Apex, ...

is pink. The base of the shell shows seven fiat evenly-spaced concentric riblets. A strong, revolving cord defines the periphery and ascends the spire. The last and penultimate whorls have four spiral riblets above the periphery, the uppermost stronger and forming the angle of a subsutural shelf. The upper whorls are smooth. The aperture is round. The simple 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 dentate by the spirals. 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 ...

is perpendicular. Hedley C. (1911) Report on the Mollusca obtained by the F.I.S. 'Endeavour' chiefly off Cape Wiles South Australia. Part 1; Zoological Results of the Fisheries Experiments 'Endeavour' (described as ''Gibbula ocellina'')
/ref>

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 els ...

to Australia and occurs off

South Australia South Australia (commonly abbreviated as SA) is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories ...

References

* Hedley, C. 1911. ''Report on the Mollusca obtained by the F.I.S. 'Endeavour' chiefly off Cape Wiles South Australia. Part 1''. Zoological Results of the Fisheries Experiments carried out by F.I.S. "Endeavour" 1: 89-114 * Cotton, B.C. 1959. ''South Australian Mollusca. Archaeogastropoda''. Handbook of the Flora and Fauna of South Australia. Adelaide : South Australian Government Printer 449 pp. * Wilson, B. 1993. ''Australian Marine Shells. Prosobranch Gastropods''. Kallaroo, Western Australia : Odyssey Publishing Vol. 1 408 pp.

External links

World Register of Marine Species
{{Taxonbar, from=Q13453082 ocellinum Gastropods of Australia Gastropods described in 1911