''Megastraea turbanica'', common name the turban star 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

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 ...

Turbinidae Turbinidae, the turban snails, are a family of small to large marine gastropod molluscs in the superfamily Trochoidea.Bouchet, P. (2014). Turbinidae Rafinesque, 1815. Accessed through: World Register of Marine Species at http://www.marinespecie ...

, the turban snails.

Description

The size of the shell attains 150 mm. The shell is moderately large and rather thin. It is brilliantly pearly inside. It is covered with a reddish-brown periostracum which becomes olivaceous on the base. The form is rather depressed with turgid

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, about six in all. The nucleus is white, blunt, imperfect. The base of the shell is flattened, bordered by a sparsely nodulous carina. 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 ...

on 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 slightly protractive, rounded, and short. It contains rather elevated riblets reaching about half way forward on the whorl from the suture (17 on the last whorl). These end in or are barely separated from the same number of stout nodules at the periphery, with a marked sulcus separating them from a similar row of nodules on the margin of the base. The base contains four somewhat undulated spiral ridges separated by subequal interspaces, except the inner pair which are smaller and closer to each other. The base is imperforate and is swollen at the base of 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 wo ...

. 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 ample. The surface of the bodyis erased, leaving visible a pearly and white substance. The pearly columella is arcuate with no anterior prominence or tooth. The 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 ...

and the base is simple and sharp. The white operculum is rounded, shelly, with three partly gyrate, very prominent, granose, narrow ribs. The spaces between them are excavated and smooth.W.H. Dall (1910) ''New Species of West American Shells''; The Nautilus v. 23, 1910
(described as ''Pomaulax turbanicus'')

Distribution

This species occurs in the Pacific Ocean off

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

, USA.

References

* Turgeon, D.; Quinn, J.F.; Bogan, A.E.; Coan, E.V.; Hochberg, F.G.; Lyons, W.G.; Mikkelsen, P.M.; Neves, R.J.; Roper, C.F.E.; Rosenberg, G.; Roth, B.; Scheltema, A.; Thompson, F.G.; Vecchione, M.; Williams, J.D. (1998). ''Common and scientific names of aquatic invertebrates from the United States and Canada: mollusks''. 2nd ed. American Fisheries Society Special Publication, 26. American Fisheries Society: Bethesda, MD (USA). . IX, 526 + cd-rom pp. * Alf A. & Kreipl K. (2011) ''The family Turbinidae. Subfamilies Turbininae Rafinesque, 1815 and Prisogasterinae Hickman & McLean, 1990.'' In: G.T. Poppe & K. Groh (eds), ''A Conchological Iconography.'' Hackenheim: Conchbooks. pp. 1–82, pls 104–245.

External links

* {{DEFAULTSORT:Megastraea Turbanica turbanica Gastropods described in 1910