Endangered
Southern giant clam
Tridacna derasa
Southern giant clam is a bivalve in the family Cardiidae (order Cardiida) — Tridacna derasa, recorded as Endangered.
Appearance
The species is also known as the smooth giant clam because of the relative lack of ribbing and scales on its thick shell. The smoothness of the southern giant clam's shell and its six to seven vertical folds help to distinguish it from its larger relative, Tridacna gigas, that has four to five folds and a rougher texture. Lack of scutes (scale-like protrusions of the shell) that are present in most other Tridacna species is a defining characteristic of this species, although in aquacultures specimens have been observed to develop scutes in at least one abnormal case.
The southern giant clam is one of the largest of the "giant clams", reaching up to 60 cm in length.
Range and habitat
The southern giant clam is native to waters around Australia, Cocos Islands, Fiji, Indonesia, New Caledonia, Palau, Papua New Guinea, Philippines, Solomon Islands, Tonga and Vietnam. Populations have also been introduced to American Samoa, Cook Islands, Marshall Islands and Samoa, and reintroduced after extinction in Guam, the Federated States of Micronesia and Northern Mariana Islands. The southern giant clam is found on the outer edges of reefs at depths of 4 to 10 meters.
Pins are Wikidata “endemic to” fields. Orange dots, when present, are GBIF occurrence tiles — survey bias included.
In crisis
Even so, specimens traded today tend to be the result of aquaculture farms rather than wild-caught individuals, because the southern giant clam was one of the first clams to be bred commercially.
CITES lists this taxon on Appendix II. Confirm the current appendix on the CITES checklist.
Southern giant clam is Endangered on this catalog because that is the IUCN category stored on Wikidata. Confirm the official criteria and any later count on iucnredlist.org.
Sources
Written for this catalog from the English Wikipedia article on Southern giant clam, Wikidata item Q1055977. Family and order context is original field-guide writing about the group, not a copied assessment of this one species. Wikipedia text is CC BY-SA. Not an IUCN assessment. Counts, when quoted, can change — confirm them on the recovery programme and on iucnredlist.org.
