giant clam

Also found in: Dictionary, Thesaurus, Wikipedia.
Related to giant clam: geoduck

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.
..... Click the link for more information.
, class Pelecypoda or Bivalvia, order Eulamellibranchia, family Tridacnidae.
References in periodicals archive ?
Using giant clam populations in the Kavieng lagoonal system of New Ireland Province, Papua New Guinea (PNG), this study derives demographic parameters from estimates of density and size-frequency distributions to provide clarity to the relative contribution of both T.
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.
A COLLECTION of giant clams which were seized by Customs officials has arrived at Blue Planet Aquarium.
The ceremony's culmination came when volunteer divers boarded boats to transport the giant clams to off-shore releasing sites.
So, the researchers wondered, "What on Earth is a giant clam doing with a living iridescent cell?
And Alaska is suddenly supplying a greater share of a world market for the giant clams that hitherto goes unsatisfied.
KEY WORDS: salinity, giant clam, Tridacna gigas, stress response, clearance rate, absorption efficiency
During each run, giant clam seeds were reared with no antibiotics or algal food in 3-[micro]m filtered unsterilized seawater, half of which was exchanged with new seawater on day 6 or day 7.
50 for salmon roe; and $3 for sea urchin, giant clam and jumbo scallop.
Amazing Rangers-blue starfish, millions of fish, exquisite coral and a giant clam which feels velvety to touch.
With visibility to 200 feet, Kosrae's waters are home to more than 172 species of hard corals -- believed to be 2,000 years old in some areas -- and 13 species of soft corals, 550 species of fish, a giant clam farm and abundant marine life.