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 ?
Giant clam larvae can be successfully cultured without provision of microalgae (Lucas 1994) and earlier research in this laboratory has confirmed this for Tridacna noae (authors' unpublished data).
With growing domestic and international concern and criticism of Chinese fishermen poaching giant clams and other endangered marine species, China began to crackdown on Tanmen's giant clam sector in early 2015.
The current title holder for the largest natural giant clam pearl is the 14-pound Pearl of Lao Tzu, which was discovered in Palawan waters.
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.
The Thai government released 299 giant clams into the Andaman Sea on Feb.
Initial inspection of the site suggested that only the larger artefacts remained, such as chunks of giant clam and baler shell, and larger pieces of bone and artefactual stone.
The zooxanthellal tubular system in the giant clam.
In Cardiff a giant clam smuggled from Indonesia was seized from a furniture store, while barn owls, otters and birds of prey - worth up to pounds 1,000 on the black market - had been found in a freezer, said Sgt Ian Guildford, of South Wales Police.
In 1998 it received an award from the International Society of Conservation Biology for its "lasting contributions to conservation" and in recognition of its work in protecting the endangered dugong, fruit bat, giant clam and hawksbill sea turtle.
Therefore, the second monograph, entitled Economics of Commercial Giant Clam Mariculture, was jointly edited by me with Professors Shang and Leung.
Wallace is standing in a morning's worth of shavings as he tells the story of Eagle Boy, a tale about a young man who, after being transformed into an eagle, is warned by the clan mother not to mess with a giant clam on the beach.