Giant clam

In Japanese Cuisine, Geoduck (mirugai) is sometimes referred to as "Giant clam".

The Giant Clam (Tridacna gigas), also known as Bear's paw, killer clam, Man-eating clam, or traditionally, pa’ua, is the largest living bivalve mollusc. One of a number of large clam species native to the shallow coral reefs of the South Pacific and Indian oceans, they weigh an average of 440 pounds and can measure as much as 1.5 meters across.

Permanently sessile in adulthood, the creature's siphon and mantle tissues act as a habitat for the green algae on which it feeds. By day, its shell remains open unless disturbed, and in this way the symbiotic algae may recieve sunlight they need to grow.

As is often the case with uncharacteristically large species, the giant clam has been historically misunderstood. Reputable scientific and technical manuals once claimed that the great mollusk had caused deaths, and the U.S. Navy Diving Manual even gave detailed instructions for releasing oneself from its grasp by severing the adductor muscles used to close its shell. Today, it is generally acknowledged that the giant clam is neither aggressive nor particularly dangerous; while it is certainly capable of holding one fast in its grip, the shell's closing action is actually a defensive response, and far too slow to pose any reasonable threat. No account of a human being trapped in this manner has ever been substantiated.

Conservation status

The IUCN lists the giant clams as vulnerable. There is concern among conservationists for the sustainability of practices among those who use the animal as a source of livelihood. The numbers in the wild have been greatly reduced by extensive harvesting for food and aquarium trade. Illegal trade in giant clam shells for use as decorative acoutrements abounds, and the meat, called Himejako in Japan, is prized as a delicacy.

External links

• Tridacna gigas entry on Animal Diversity Web
• Giant clam entry on the IUCN Red List of threatened species
• Giant clam conservation research project at Universiti sains Maylaysia