At sign of disturbance, the shell valves close up. Habitat Some live in coral reefs, some on sandy substrates. Although there are no authentic cases of people being trapped and drowned by the giant clam, it is possible for a person to get caught between the valves since the clam is well-camouflaged. The valves were formerly frequently used as wash or baptismal basins. In the early 1930's, a crude pearl weighing 7kg was found in a tridacnid clam in the Phillipines.
Giant clams have a symbiotic relationship with algae.
The algae live on the mantle margin and feed on portions of the giant clam's food. Van Nostrand Reinhold Company, New York. Reference written by Kari Tervo. Page last updated 12 February 1996. Sponsored in part by the Interagency Education Research Initiative, the Homeland Foundation and the University of Michigan Museum of Zoology .