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 ?
It also ''imperils the marine diversity in the shoal and threatens the marine ecosystem'' in the entire body of water, citing instances where Chinese fishermen were documented to have ''unlawfully dredged the area and illegally harvested giant clams and coral.
And Alaska is suddenly supplying a greater share of a world market for the giant clams that hitherto goes unsatisfied.
Unpopulated (although there is a small post office) you can walk around it, swim to a nearby sand-bar, watch the hermit crabs and dive down to the giant clams.
He also meets a loveable koala and marvels at the wealth of beauty beneath the waves off Australia's Gold Coast, where he spots several giant clams among the many shimmering reefs.
As you near the end of your tour, you'll be treated to an array of sea snakes, sea horses, giant clams and groupers.
Aquaculture operations use thousands of litres of algal culture daily to feed the larval and juvenile stages of farmed species including oysters, prawns, abalone, barramundi and giant clams.
The festival also heard that the oceans' floors contains other colonies of gas-fuelled life, including giant clams, mussels and shrimps.
He cited instances of harmful fishing practices, such as blast fishing, cyanide fishing, harvesting of giant clams, catching of turtles, and other endangered species.
Giant clams (Cardiidae: Tridacninae) are highly emblematic, heavily targeted coral reef species throughout their Indo-Pacific distribution, from East Africa and the Red Sea to the central Pacific Ocean (bin Othman et al.
Its outstanding facilities include the Marine Ecology Research Centre, which, among other things, is concerned with cultivating coral, giant clams and endangered fish species from the waters around Borneo.