Small Giant Clam

Bivalves have two valves on the mantle. These siphon water through the body to extract oxygen from the water using the gills and to feed on algae. The maxima is less than one-third the size of the true giant clam (Tridacna gigas).

Shell. Adults develop a large shell that adheres to the substrate by its byssus, a tuft of long, tough filaments that protrude from a hole next to the hinge.

Mantle. When open, the bright blue, green or brown mantle is exposed and obscures the edges of the shell which have prominent, distinctive furrows. The attractive colours of the small giant clam are the result of crystalline pigment cells. These are thought to protect the clam from the effects of intense sunlight, or bundle light to enhance the algae's photosynthesis. Maxima produce the color white in their mantle by clustering red, blue and green cells, while individual T. derasa cells are themselves multi-colored.

The small giant clam has the widest range of all giant clam species. It is found in the oceans surrounding East Africa, India, China, Australia, Southeast Asia, the Red Sea, and the islands of the Pacific. Found living on the surface of reefs or sand, or partly embedded in coral, the small giant clam occupies well-lit areas, due to its symbiotic relationship with photosynthetic algae, which require sunlight for energy production.