''Guildfordia yoka'', the yoka star turban, 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 ...

of deep-water

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 Turbinidae, the turban snails.

Distribution and habitat

This tropical marine species occurs in the Western Pacific off

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

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 ...

, found at depths between .Sealife Base
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Description

The size of the shell varies between . The color pattern of the shell varies from very light brownish to purple-brown. Some specimens contain only 6

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 instead of 7 as in the holotype. The upper whorls are smooth, then follows 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 ...

with scarcely 2 rows of granules, instead of 7 or 8. Towards the keel it has very irregular radiating ribs, which leave however a nearly smooth zone above the keel, with only a few spiral striae. The base of the shell is less convex than the upper part. Some specimens lack the rose-coloured line round the umbilical callosity. 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 oval, thick, with the nucleus in the external lower corner. The outer surface is slightly rugose, by irregular wrinkles, almost parallel with the basal margin of the operculum. The nucleus is marked by an olive spot.

Biology

Embryos of ''Guildfordia yoka'' develop into free-swimming planktonic larvae with several bands of cilia (

trocophore A trochophore (; also spelled trocophore) is a type of free-swimming planktonic marine larva with several bands of cilia. By moving their cilia rapidly, they make a water eddy, to control their movement, and to bring their food closer, to captu ...

). Later they develop into juvenile veligers, finally into fully grown adults.

Gallery

File:Guildfordia yoka delicata 01.JPG, ''Guildfordia yoka'' File:Guildfordia yoka.jpg, A shell of ''Guildfordia yoka'' Jousseaume, 1888, measuring 26.3 mm diameter, trawled at 100 m off Minabe, in

. File:Guilfordiayoka.jpg, Apical view of a shell of ''Guildfordia yoka''

References

* 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

*
Guildfordia yoka
' on

OBIS The Ocean Biodiversity Information System (OBIS), formerly Ocean Biogeographic Information System, is a web-based access point to information about the distribution and abundance of living species in the ocean. It was developed as the information ...