giant clam

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Related to Tridacna gigas: Tridacna squamosa

giant clam,

common name for the largest bivalve mollusk in the world, Tridacna gigas, also known as the bear's paw clam. The giant clam may weigh over 500 lb (225 kg) and attain a length of over 4 ft (120 cm). The heavy shell is coarsely fluted and toothed. Giant clams are found in the South Pacific and Indian oceans, especially in the Great Barrier Reef. They lie with the hinge downward in the coral reefs, usually in shallow water. The adductor muscles, which cause the shell to close, are a source of food for people of the South Pacific. The shell closes very slowly; stories of human beings trapped within giant clams have never been substantiated. Small giant clam shells have been used as birdbaths and baptismal fonts. An interesting symbiosis occurs between a unicellular green alga (Zooanthella) and the clam. The algae live in the tissues of the clam's siphon and mantle; they are able to obtain the sunlight needed for photosynthesis because the clam lies with its valves opening upward and part of the thick, purple mantle extruding over the shell. In addition, there are crystalloid vesicles on the mantle surface that let in sunlight, thus allowing the algae to live deep within the tissues. The clam uses the algae as a supplementary or perhaps even a major source of food. Tridacna gigas is classified in the phylum MolluscaMollusca
, taxonomic name for the one of the largest phyla of invertebrate animals (Arthropoda is the largest) comprising more than 50,000 living mollusk species and about 35,000 fossil species dating back to the Cambrian period.
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, class Pelecypoda or Bivalvia, order Eulamellibranchia, family Tridacnidae.
References in periodicals archive ?
While this species is not as threatened as Tridacna gigas, its numbers in Singapore are very low and the population is probably not currently self-sustaining.
Similar differences between male and female maturity stages were also found for Tridacna gigas on the basis of semiquantitative indices only (Nash et al.
1988) for Tridacna gigas is confirmed for Tridacna maxima.
Reproduction in the giant clams Tridacna gigas and T.
Recruitment of the giant clams Tridacna gigas and T.
A histological study of the reproduction in the giant clam Tridacna gigas in the north-central Great Barrier Reef.
However, there is a scarcity of information on the effects of salinity variations on giant clams in general and Tridacna gigas in particular (Mingoa 1990, Blidberg et al.
Cultured Tridacna gigas juveniles were exposed to 3 salinity treatments (18, 25, and 35 [as the control]) for 14 days.
In this study, CR and AE were investigated in Tridacna gigas exposed to low salinity for 14 days.
It was found in an earlier study that after 2 wk of exposure of Tridacna gigas to different salinities, the osmotic concentration of the extracellular fluid varied with salinity level (Mingoa 1990), indicating that T.
Hence, no such compensation were demonstrated by Tridacna gigas juveniles.
Effect of increased irradiance and thermal stress on the symbiosis of Symbiodinium microadriaticum and Tridacna gigas.