''Coelotrochus viridis'', common name the green top shell, 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 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 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.Rosenberg, G. (2012). ''Coelotrochus viridis'' (Gmelin, 1791). Accessed through:

World Register of Marine Species The World Register of Marine Species (WoRMS) is a taxonomic database that aims to provide an authoritative and comprehensive list of names of marine organisms. Content The content of the registry is edited and maintained by scientific specialist ...

at http://www.marinespecies.org/aphia.php?p=taxdetails&id=598205 on 2012-11-23

Description

The length of the shell varies between 15 mm and 25 mm. The solid shell has a conical shape with nearly straight outlines and is false-umbilicate. 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 ...

of the upper surface consists of 5 series to each

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 ...

of rounded bead-like granules, between which are visible numerous very minute spiral striae, in the interstices of which oblique incremental striae are prominently shown under a lens. The base of the shell is concentrically striate with unequal striae that disappear toward the outer edge. The colour of the shell is dull grey, whitish, or greenish. The apex is acute. 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 ...

is very small, with 1½ whorls, which have a slightly rugose surface. The about 7 whorls are nearly planulate, or sometimes a little bulging at the upper and lower margins. 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 strongly angled or carinate at the periphery. The base of the shell is plano-concave. The suture is rather deep. 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 suboval to quadrangular and is nacreous within. The outer lip is convex, sharp, with a smooth marginal band inside. The outer part is narrow, white, and opaque. The inner part is broader, iridescent, and smooth. Further inside it is lirate. The basal lip is thickened, subdentate, uniting with the columella in a regular curve. The columella is oblique, with a deep fold near its insertion, and is smooth within. The umbilical area contains 3 to 4 spiral ribs. The interstices are nacreous. The umbilicus is narrow and deep or partly filled up by a white callus. The parietal wall is transversely striate or nearly smooth, with a lightbrown callus. The animal is yellowish-brown. Its foot is reddish or purplish-brown. The filaments are white, 3 on each side. The head-lobes are smooth and rounded, and joined across the head. The eyes are on rather long white peduncles. Suter H. (1913-1915), Manual of New Zealand Mollusca; Wellington, N. Z. :J. Mackay, govt. printer,1913-1915
(described as ''Trochus viridis'')

Distribution

This marine species is endemic to

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 ...

References

* Powell A W B, ''New Zealand Mollusca'', William Collins Publishers Ltd, Auckland, New Zealand 1979 * Miller M & Batt G, ''Reef and Beach Life of New Zealand'', William Collins (New Zealand) Ltd, Auckland, New Zealand 1973 * Marshall, B.A., 1998. ''A review of the Recent Trochini of New Zealand (Mollusca: Gastropoda: Trochidae)''. Moll. Res.1, 19:73-106

External links

To World Register of Marine Species
* {{Commons category viridis Gastropods of New Zealand Gastropods described in 1791