The Giant Clam 'Tridacna Gigas' is the largest living bivalve mollusk. The shell may reach up to 1.5 meters in length. They can weigh more than 200 kilograms (440 lb) measure as much as 120 cm (47 in) across, and have an average lifespan in the wild of 100 years or more.
These huge bivalve mollusks are found in shallow waters of the Pacific Ocean, from Thailand and Japan to Australia and Micronesia. They occupy coral reef habitats, typically within 20 meters of the surface. They are most common found in shallow lagoons and reef flats, and are typically embedded in sandy substrates or those composed of coral rubble. However, the giant clam’s range has reduced since the 1970s due to over-harvesting.
Giant clams cannot completely close their shell once fully grown.