''Tridacna crocea'', the boring clam, crocus clam, crocea clam or saffron-coloured clam, is a species of

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

in the family Cardiidae. It is native to the Indo-Pacific region. It is occasionally found in the aquarium trade Huelsken, T., Keyse, J., Liggins, L., Penny, S., Treml, E.A., Riginos, C. (2013) A Novel Widespread Cryptic Species and Phylogeographic Patterns within Several Giant Clam Species (Cardiidae: Tridacna) from the Indo-Pacific Ocean. PLoS ONE
DOI: 10.1371/journal.pone.0080858
where it is often simply referred to as ''crocea''.

Description

The boring clam is the smallest clam in the

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...

Tridacninae Tridacninae, common name, the giant clams, is a taxonomic subfamily of very large saltwater clams, marine bivalve molluscs in the family Cardiidae, the cockles. Description This subfamily contains the largest living bivalve species, including '' ...

and grows to a maximum shell size of . It has two, thick valves joined by a hinge which is typically between a third and less than a half of the width of the shell. Typically shells are slightly to moderately elongate, and the animal is strongly inflated, especially near the hinge. The upper valve has six to ten flattish folds which interlock at the margin with similar folds on the lower valve so that they can clamp together and the shell can close tightly. The lower valve has slits through which the byssal threads emerge which secure the animal to the seabed. This clam burrows into the

substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached ** Substrate (locomotion), the surface over which an organism lo ...

and this process tends to wear away the outer surface of the valves and smooth them off. They also may become distorted by burrowing into substrates of uneven hardness. The colour of the valves is generally greyish-white, sometimes with a hint of pink-orange, yellow or orange colour -this colouration can form a band near the top margin, especially on the interior surface. The

mantle A mantle is a piece of clothing, a type of cloak. Several other meanings are derived from that. Mantle may refer to: *Mantle (clothing), a cloak-like garment worn mainly by women as fashionable outerwear **Mantle (vesture), an Eastern Orthodox ve ...

, the soft body wall which covers the animal's internal organs, projects from between the valves when they are open and is brightly coloured. It can be various shades of blue, green, purple, gold, orange or brown, often patterned with spots, stripes or squiggles. It has many small protrusions on the exposed surface and a line of simple eyes near the margin. The inhalent siphon, through which water is drawn into the shell, is surrounded by many small tentacles and the exhalent siphon is often long and tubular. Image:Boring giant clam.jpg Image:Tridacna crocea.jpg Image:Tridacna crocea 01 by Line1.jpg

Distribution and habitat

The boring clam is native to the Indo-Pacific. Its range extends from Malaysia, Vietnam and

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 ...

to Indonesia, the Philippines, Palau, New Guinea,

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

, the Solomon Islands and Vanuatu. At one time it was known from Guam and the Northern Mariana Islands but it may now be locally extinct in these locations. Its typical habitat is embedded in massive corals.

References

* Dautzenberg P. (1929). Contribution à l'étude de la faune de Madagascar: Mollusca marina testacea. Faune des colonies françaises, 3(4): 321-636, pls 4-7. Société d'Editions géographiques, maritimes et coloniales, Paris. * Liu, J.Y. uiyu(ed.). (2008). Checklist of marine biota of China seas. China Science Press. 1267 pp.

External links

*
Lamarck (J.-B. M.) de. (1819). Histoire naturelle des animaux sans vertèbres. Tome 6(1): vi + 343 pp. Paris: published by the author.

Reeve, L. A. (1862). Monograph of the genus Tridacna. In: Conchologia Iconica, or, illustrations of the shells of molluscous animals, vol. 14, pl. 1-8 and unpaginated text. L. Reeve & Co., London.

Poorten, J.J. ter, 2009. The Cardiidae of the Panglao Marine Biodiversity Project 2004 and the Panglao 2005 Deep-Sea Cruise with descriptions of four new species (Bivalvia). Vita Malacologica 8: 9-96

Iredale, T. (1937). Mollusca. In: Whitley, G. P. (ed). Middleton and Elizabeth Reefs, South Pacific Ocean. Australian Zoologist. 8(4): 232-261, pls 15-17
{{Commons, Tridacna crocea crocea Fauna of Timor Bivalves described in 1819 Taxonomy articles created by Polbot