Nutrition of giant clams

摘要: THE relative importance of the different sources of nutrients to the nutrition of giant clams has been controversial for at least one hundred years. The first debate centred on whether the green cells in giant clams were actually algae or a special type of animal cell (Brock 1888). After confirmation of the presence of symbiotic dinoflageIlates, the same type of brown algae found in reef corals and other cnidarians, attention shifted to whether nutrients from these symbionts originated from digestion of the algae by the clam, or from transfer of compounds from live and intact algae (Yonge 1936, 1953, 1980, Muscatine 1967, Goreau et a!. 1973, Fankboner 1971, Trench et al. 1981, Reid and Fankboner 1990). While this argument has lingered in the literature for over 50 years, most of the major issues are now resolved, as details of the morphological, physiological and biochemical relationship between alga and host have been described. More recently the clam's ability to filter particulate material from the water has been assessed, and its potential importance in supplying essential nutrients to larvae, juvenile and adult clams characterised (Yonge 1936, Klumpp et al. 1992, Southgate, 1988). Other less studied aspects of nutrition of giant clams include uptake of dissolved inorganic and organic molecules from seawater (Goreau et al. 1973, Fankboner 1971) and a potential role for suspension feeding (Reid and King 1988). This paper summarises what is known about acquisition of nutrients in giant clams, paying special