''Trochus squarrosus'' 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 ...

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 height of an adult shell attains 35 mm, its diameter 40 mm. The thick, umbilicate shell has a conic-pyramidal shape. It is radiate with white and rose color. it contains 9

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 embryonic smooth, the following planulate. The shell is sculptured with spiral series of regular beads the remaining whorls subexcavated in the middle, with three series of granules on the upper part and a series of oblique short folds below. 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 carinated, with 16 to 24 folds crenulating its periphery. The base of the shell is planulate, with six concentric granulose lirae, separated by interstices as wide as the ridges. 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 ...

rhomboidal and lirate within. The umbilical area spirally plicate.H. Pilsbry, Manual of Conchology XI, Academy of Natural Sciences, Philadelphia
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Distribution

This species occurs in the Indian Ocean off

Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...

References

* Dautzenberg, Ph. (1929). ''Contribution à l'étude de la faune de Madagascar: Mollusca marina testacea''. Faune des colonies françaises, III(fasc. 4). Société d'Editions géographiques, maritimes et coloniales: Paris. 321–636, plates IV-VII pp

External links

* {{DEFAULTSORT:Trochus Squarrosus squarrosus Gastropods described in 1822