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 (6). 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 (6) (7). The zooxanthellae transforms carbon dioxide and dissolved nitrogen, such as ammonium, into carbohydrates and other nutrients for their hosts (7).
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 southern giant clam occurs in spring (7).