Everything about Giant Clam totally explained
» In Japanese cuisine, Geoduck (mirugai) is sometimes referred to as "giant clam".
The
giant clam,
Tridacna gigas, 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 can weigh more than 227 kilograms (500 pounds) and measure as much as 1.2 metres (4 feet) across, and have an average lifespan in the wild of 100 years or more.
Sessile in adulthood, the creature's
mantle tissues act as a
habitat for the
symbiotic single-celled
dinoflagellate algae (
zooxanthellae) from which it gets its nutrition. By day, the clam spreads out its mantle tissue so that the algae receive the
sunlight they need to
photosynthesize.
History and Legend
As is often the case with uncharacteristically large species, the giant clam has been historically misunderstood. Known in times past as the
killer clam or
man-eating clam, reputable scientific and technical manuals once claimed that the great mollusc had caused deaths; versions of 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.
In a colorful account about the discovery of the so-called
Pearl of Lao Tzu, a
Tridacna pearl, Wilburn Cobb said he was told that a
Dyak diver drowned by the
Tridacna closing its shell on his arm.
Today the giant clam is considered neither aggressive nor particularly dangerous. While it's certainly theoretically capable of holding one fast in its grip, in reality the shell's closing action is a defensive response, not an aggressive one, and the process of closing the shell valves is slow, far too slow to pose a serious threat. In other words, the clam is incapable of suddenly snapping shut on a person's arm or leg and thus drowning them.
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 overharvesting for food and the aquarium trade. On the
black market, giant clam shells are sold as decorative accoutrements, and the meat, called
Himejako in
Japan, is prized as a delicacy.
Image:Giant_clam_with_diver.jpg|The largest of all clam species
Image:Giant_clam_detail.jpg|Mantle detail 1
Aquaculture
Recent developments in
aquaculture, specifically at
Harbor Branch Oceanographic Institute in
Ft. Pierce, Florida and in the
Marshall Islands, are allowing T. Gigas to be tank raised for both use in home
aquariums and release into the wild.
Further Information
Get more info on 'Giant Clam'.
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