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Cypraea tigris

Cypraea tigris, Photo: Michael Lahanas

Cladus: Eukaryota
Supergroup: Opisthokonta
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Protostomia
Cladus: Spiralia
Cladus: Lophotrochozoa
Phylum: Mollusca
Classis: Gastropoda
Subclassis: Orthogastropoda
Superordo: Caenogastropoda
Ordo: Sorbeoconcha
Subordo: Hypsogastropoda
Infraordo: Littorinimorpha
Superfamilia: Cypraeoidea
Familia: Cypraeidae
Subfamilia: Cypraeinae
Genus: Cypraea
Species: Cypraea tigris

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Cypraea tigris, commonly known as the tiger cowry, is a species of cowry, a large sea snail, a marine gastropod mollusk in the family Cypraeidae, the cowries. Measuring up to 15 cm (6 in) in length, the shell is round, with black spots on a white background, and is usually covered by the mantle when the cowrie is roving the sea floor and coral reefs. The natural range of this species is the western Pacific and northern Indian Oceans, at depths of 10 to 40 metres. The populations have been reduced by habitat destruction and commercial shell collecting.

Taxonomy

The tiger cowry was one of the many species originally described by Linnaeus in his 18th century work, Systema Naturae, and the species still bears its original name of Cypraea tigris.[2] Its specific epithet tigris relates to its common name "tiger" (the shell however is spotted not striped). This species is the type species of the genus Cypraea.

The subspecies Cypraea tigris schilderiana was recognized by Cate in 1961. It differs from Cypraea tigris in its large size (10–13 cm) and the lack of a thick marginal callus. This subspecies is found in the Hawaiian Islands, Johnston Island, and Vietnam. [3][4]

Description

Roughly egg-shaped and dextral, the glossy shell is large and heavy for a cowry. It measures up to 15 cm (6 in) in length, and the upper or dorsal side is white, pale bluish-white, or buff, densely covered with dark brown or blackish barely circular spots. Akin to many other Cypraea snails, the shells surface is notably effulgent, as if it were deliberately polished. There is sometimes a blurred red line along the length of the shell at the midline on the dorsal surface. The lower margins are rounded (that is, there is no sharp margin between the upper and lower surfaces of the shell as is found in some other cowries). The ventral side is white or whitish, and the shell opening is lined with tooth-like serrations.[5]

As is the case in almost all cypraeids, two lateral extensions of the mantle are able to extend so as to cover the shell completely, meeting at the midline of the dorsal surface. The mantle can also withdraw into the shell opening when threatened. In this species, the exterior surface of the mantle has numerous pin-like projections that are white-tipped.

Distribution and habitat

The tiger cowrie is found on the ocean floor in the Indian and western Pacific Oceans, across the waters of Micronesia and Polynesia, the Coral Sea and around the Philippines. Along the Australian Coast it is found from Northern New South Wales to northern Western Australia, as well as Lord Howe Island, and along the east coast of Africa including Madagascar.[5] Found between depths of 10 and 40 metres (35–130 ft), it is often associated with live coral colonies, such as the table-forming Acropora,[6] either found on the reefs themselves or the sandy sea bottom nearby.[5] Once common, it is now much less abundant due to shell collecting and the destruction of its habitat by such processes as dynamite fishing, especially in shallower areas.[5] Carnivorous, the adult tiger cowrie eats coral and various invertebrates, while juveniles eat algae.

This species is endangered in Singapore.[6]

Human use

Despite the fact that this species does not occur in the Mediterranean Sea, shells of the tiger cowrie and the related panther cowrie, Cypraea pantherina, have been unearthed at Pompeii, the ancient Roman city near Naples, Italy, where these shells may have been used as some form of ornament.[7]

It is also conceivable that the shells were part of a natural history collection. There was an interest in natural history at the time, as exemplified by Pliny the Elder who wrote extensively about seashells in his book Natural History and who died investigating the eruption of Vesuvius.

The shells of this species of cowry are still popular among shell collectors, and are also used as a decorative object, even in modern times.

The shell of Cypraea tigris is believed to help to facilitate childbirth: some women in Japan hold a shell of this species during childbirth.

Large cowry shells such as that of this species were used in Europe in the recent past as a frame over which sock heels were stretched for darning, i.e. instead of using a darning egg. The cowry's smooth surface allows the darning needle to be positioned under the cloth more easily than when using a darning mushroom made of wood.

References

1. ^ IUCN 2009. IUCN Red List of Threatened Species. Version 2009.1. <www.iucnredlist.org>. Downloaded on 06 September 2009.
2. ^ a b (Latin) Linnaeus, C. (1758). Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.. Holmiae. (Laurentii Salvii). p. 211.
3. ^ Foin, T. C. (1972). "Ecological influence on the size of Cypraea tigris L., 1758, in the Pacific". Journal of Molluscan Studies 40: 211. http://mollus.oxfordjournals.org/cgi/pdf_extract/40/3/211.
4. ^ Kay E. A. 1961. On Cypraea tigris schilderiana Cate. The Veliger 4: 36-40
5. ^ a b c d Poutiers, J. M. (1998). "Gastropods". in Carpenter, K. E. FAO Species Identification Guide for Fishery Purposes: The living marine resources of the Western Central Pacific Volume 1. "Seaweeds, corals, bivalves and gastropods". Rome: United Nations FAO. pp. 494–495. ISBN 92-5-104051-6. ftp://ftp.fao.org/docrep/fao/009/w7191e/w7191e43.pdf.
6. ^ a b (file created 1 April) 2009. Singapore Red Data Book 2008. Accessed 6 September 2009.
7. ^ Jashemski, W. M. F.; Meyer, Frederick Gustav (2002). The natural history of Pompeii. Cambridge: Cambridge University Press. pp. 306–07. ISBN 0521800549.

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Source: Wikispecies, Wikipedia: All text is available under the terms of the GNU Free Documentation License