Eating in the Dark

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Science  05 Nov 2004:
Vol. 306, Issue 5698, pp. 943
DOI: 10.1126/science.306.5698.943c

Bivalves can live relatively long lives in cold waters, and it has been suggested that cold temperature promotes longevity by reducing metabolic rates. Buick and Ivany counted the growth bands in the fossil clam Cucullaea raea, which lived in shallow waters off the Antarctic Peninsula about 45 million years ago, and found individuals that had reached the ripe old age of 100 years. When they measured the carbon and oxygen isotopic concentrations within the bands, however, they found that the clams had lived in relatively warm waters (with mean temperatures of 14°C) and that they did not grow much in the summertime. This seems odd because during the summers, when the sun never set, the waters would be full of nutritious phytoplankton. Instead, the data suggest that the shells grew during the austral winter, when there was little light and less food, with the clams adopting the strategy of devoting the less harsh summer months to reproduction in order to enhance larval survival. Hence, clam longevity may be tied to low food supplies and lean shells rather than to cold temperatures. — LR

Geology 32, 921 (2004).

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