Giant clam (Tridacna) resources

Abstract

Tridacna spp. which are known as giant clams are highly specialized bivalves. They live exclusively in shallow waters of the coral reef formations. They are sessile, found attached to or biuried in corals and are tightly fastened to the substrate with byssus. The family Tridacnidae are protandrous hermaphrodites (Wada, 1952). The growth is slow whicl; is about 5 cm/year (Rosewater, 1965). The lifespan is presumed to be long but no precise information is available. Tridacnids are not entirely dependent on the ciliary mechanism for food. They are able to 'farm' their food in their own tissues due to an unusual association with large numbers of unicellular symbiotic algae— Zooxanthellae (Yonge, 1963). In addition to that, the Tridacnidae serve as hosts to a number of other organisms such as shrimps as commensals. The giant clams are a common resource in manv parts of the Andaman and Nicobar Islands and the paper presents their distribution as observed at the centres surveyed.