This family contains the largest living bivalve species, including Tridacna gigas, the giant clam. They have heavy shells, fluted with 4–6 folds. The mantle is usually brightly coloured. They inhabit coral reefs in warm seas in the Indo-Pacific region. Most of these clams live in symbiosis with photosynthetic dinoflagellates (zooxanthellae).
Sometimes the giant clams are still treated as a separate family Tridacnidae, but modern phylogenetic analyses included them in the family Cardiidae as a subfamily. Two recent genera and eight species are known:
- WoRMS. (2009). Tridacnidae. Accessed through the World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=196336 on 2009-01-10.
- Schneider,J. Phylogeny of cardiid bivalves (cockles and giant clams): revision of the Cardiinae and the importance of fossils in explaining disjunct biogeographical distributions. Zoological Journal of the Linnean Society, 2002,136, 321–369
- Keys,J.L., Helay,J.M. Relevance of Sperm Ultrastructure to the Classification of Giant Clams (Mollusca, Cardioidea, Cardiidae, Tridacninae)(in: Harper et al., (Eds) The Evolutionary Biology of the Bivalvia, Geological Society Special Publication No 177, 2000)
- Schneider, J.A.,and O´Foighil, D. Phylogeny of Giant Clams (Cardiidae: Tridacninae) Based on Partial Mitochondrial 16S rDNA Gene Sequences. Molecular Phylogenetics and Evolution Vol. 13, No. 1, October, pp. 59–66, 1999