|Nutrition in giant clams (Tridacnidae)|
Fankboner, P.V.; Reid, R.G.B. (1990). Nutrition in giant clams (Tridacnidae), in: Morton, B. (Ed.) The Bivalvia: Proceedings of a Memorial Symposium in honour of Sir Charles Maurice Yonge (1899-1986) at the 9th International Malacological Congress, 1986, Edinburgh, Scotland, UK. pp. 195-209
In: Morton, B. (Ed.) (1990). The Bivalvia: Proceedings of a Memorial Symposium in honour of Sir Charles Maurice Yonge (1899-1986) at the 9th International Malacological Congress, 1986, Edinburgh, Scotland, UK. Hong Kong University Press: Hong Kong. ISBN 962-209-273-X. 355 pp., more
|Authors|| || Top |
- Fankboner, P.V.
- Reid, R.G.B.
Tridacnids derive their nutritional requirements from filter feeding, uptake of dissolved matter through their epidermis, and photosynthates (principally glucose) released by masses of the symbiontic zooxanthella Symbiodinium microadriaticum living within blood spaces of the hypertrophied siphons. Zooxanthellae also provide a holozoic food source for tridacnids. Senescent zooxanthellae are phagocytosed from the general population living in the host clam's blood spaces by amoebocytes. Culled algal cells are rendered within the blood cell's digestive vacuoles by lysosomes. The unusually large kidneys of tridacnid clams facilitate final intracellular digestion of degenerated zooxanthellae. In addition to planktonic Crustacea and diatoms, tridacnids may filter feed upon large masses of zooxanthellae periodically released by heat-stressed hermatypic corals. Particulate and dissolved carbon are absorbed through the microvillous surface of the siphons and other exposed soft tissues. Feeding behaviour of tridacnids has a marked circadian rhythm, which cues its gastric digestive system. The digestive diverticula of tridacnid clams may be considered an organ of both secretion and absorption. Nutritional opportunism, leading to gigantism within the Tridacnidae, is discussed.