''Stomatella planulata'', common name the flattened stomatella, 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 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 length of the shell varies between 15 mm and 30 mm. The oval shell is much flattened. 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. Spires are ...

is very minute, and very near the end. 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 ...

is almost as long as shell, its margins level and it is not arched. Oval-oblong in contour, the two sides are about equally curved. The surface is shining, very densely and minutely striate in the direction of the

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. The color is very deep blackish-olive with white dots, or finely variegated and marbled all over with gray and olive-brown. Under a lens it is finely articulated on the striae. The shell contains three

s and a minute spire not projecting beyond the general outline of the shell. The oval aperture is very large. The columellar and

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 ...

margins are equally curved. The upper end is rounded with a pearly callus filling the angle. The interior is nacreous, with blue-green and fiery-red reflections

Distribution

This species occurs in the Indian Ocean off

Tanzania Tanzania (; ), officially the United Republic of Tanzania ( sw, Jamhuri ya Muungano wa Tanzania), is a country in East Africa within the African Great Lakes region. It borders Uganda to the north; Kenya to the northeast; Comoro Islands ...

; in the Pacific Ocean off Japan and the

Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

and in the Southwest Pacific.

References

* Vaught, K.C. (1989). ''A classification of the living Mollusca''. American Malacologists: Melbourne, FL (USA). . XII, 195 pp. * Poppe G.T., Tagaro S.P. & Dekker H. (2006) ''The Seguenziidae, Chilodontidae, Trochidae, Calliostomatidae and Solariellidae of the Philippine Islands''. Visaya Supplement 2: 1–228. page(s)

External links

* {{DEFAULTSORT:Stomatella Planulata planulata Gastropods described in 1816