giant clam

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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 ?
The giant clams showed reduced CRs in reduced salinities (25 and 18).
Molluscan hemocytes packed with large colorless granules have been observed only in giant clams (the Tridacnidae).
They examined online data and publications that date back to the 1900s on the taxonomy of giant clams and their global distribution.
While giant clams are found in the shallow coral reefs of the South China Sea, such as in the Paracels, Spratlys and at Scarborough Shoal, the quality of giant clams from different areas varies.
Since the opening of our Marine Ecology Research Centre in 2007, we have successfully cultivated 500 giant clams of seven different species and 8,000 coral fragments in our ocean nursery through our in-house guest participation programme.
The southern giant clams, which can grow up to 60cm in length, were part of a large consignment intercepted and confiscated after being illegally imported into the country.
But he said authorities were unable to retrieve corals, giant clams and whale sharks allegedly poached by the fishing boats first spotted in Scarborough Shoal on April 8.
Amman, March 11 (Petra) -- Jordan Customs Department (JCD) personnel in the southern region have blocked an attempt to smuggle coral reefs, giant clams and ornamental fish out of the country.
Worldwide, giant clams are dwindling in number because they aren't capable of repopulating on their own in their coral reef habitats; now they are getting help from clam farms.
The Thai government released 299 giant clams into the Andaman Sea on Feb.