This subfamily contains the largest living bivalve species, including "Tridacna gigas", the giant clam. The "maxima" is less than one-third the size of the true giant clam ("Tridacna gigas"). The giant clam, "Tridacna gigas", is common on the reef shelf. "Tridacna gigas" is one of the most endangered clam species. The giant clam ("Tridacna gigas") is generally considered to be the largest bivalve mollusc. "Tridacna maxima" and largest clam species, "Tridacna gigas" is also found in the lagoon. "Tridacna gigas" reproduce sexually and are hermaphrodites (producing both eggs and sperm).