Tridacna gigas, the giant clam, is the most well-known species of the giant clam genus Tridacna. Giant clams are the largest living bivalve mollusks. Several other species of "giant clams" in the genus Tridacna, are often misidentified as Tridacna gigas.
Giant clam
Mantle of giant clam with light-sensitive spots which detect danger and cause the clam to close
Giant clam in Bunaken island, Sulawesi, Indonesia
Empty giant clam shell in the French National Museum of Natural History
Tridacna is a genus of large saltwater clams, marine bivalve molluscs in the subfamily Tridacninae, the giant clams. Many Tridacna species are threatened. They have heavy shells, fluted with 4 to 6 folds. The mantle is often brightly coloured. They inhabit shallow waters of coral reefs in warm seas of the Indo-Pacific region. These clams are popular in marine aquaria, and in some areas, such as the Philippines, members of the genus are farmed for the marine aquarium trade. They live in symbiosis with photosynthetic algae (zooxanthellae). Some species are eaten by humans.
Tridacna
Drawing of a Tridacna spp. (NOAA)
One of the two clam stoups of the Église Saint-Sulpice in Paris, carved by Jean-Baptiste Pigalle.
Tridacna crocea