Fluted clam  (Tridacna squamosa)

The fluted clam, also known as the scaled clam, can be identified by the large, leaf-like fluted scales on its shell (4) (5), which are often used as shelter by organisms such as small crabs, clams, and other invertebrates (6). The mantle is normally brown, generally mottled with vivid green and blue spots or wavy lines (5) (7) (8).

Known from the Red Sea and east African coast across the Indo-Pacific to the Pitcairn Islands, and an introduced population exists in the waters around Hawaii (2).

Found at the sandy bottom of coral reefs at depths of around 15 to 20 m, typically anchored amidst Acropora corals (9).

Tridacna clams have muscles for opening and closing their shell and a foot for attaching themselves to rocks. They breathe through gills and feed through a mouth (10). Most clams fulfill their nutritional requirements by filter feeding and absorbing dissolved organic compounds from the water, but tridacnid clams have gone further than this by using zooxanthellae algae in their tissue to manufacture food for them (10) (11). The zooxanthellae transforms carbon dioxide and dissolved nitrogen, such as ammonium, into carbohydrates and other nutrients for their hosts (11).

When Tridacna clams first attain sexual maturity, they are male, but about a year later become hermaphrodites, possessing both male and female reproductive organs. However, the release of sperm and eggs are separate in order to prevent self-fertilisation, although self-fertilisation can occur. The breeding season of the fluted clam occurs in winter (11).

The fluted clam is a popular food item and is traded domestically and internationally, with 34 countries recorded to export the species over the period from 1994 to 2003 (2). Live specimens have also been exported for the aquarium trade (2). However, export has reduced and is now minimal, with significant international trade only really coming from the Solomon Islands (2).

The fluted clam is bred in captivity in a number of countries, supplying domestic and international demand. Harvest of wild specimens is either regulated or prohibited completely in many range states, although illegal harvesting may still occur (2).

For more information on the fluted clam see:

• Lukan, E.M. (2000) Critter Corner: Tridacna squamosa. Fish ‘N' Chips: A Monthly Marine Newsletter, 2000:0. Available at:
  http://animal-world.com/encyclo/fishnchips/aug2000/fnc0800.html

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