LElTER TO THE EDITOR Metabolic Rate-Body Size Relations in Marine Mammals

Platt & Silvert (1981) used a novel dimensional analysis to generate the hypotheses that metabolic rates of aquatic organisms, including marine mammals, vary as body mass (W) raised to the power 2/3, whereas those of terrestrial animals, including mammals, vary as W3/4. As they noted, their prediction for terrestrial mammals is "consistent with much of the research that has been carried out " (p. 858); for interspecific comparisons spanning a wide range of body masses, basal metabolic rates of terrestrial mammals tend to vary as W3/4 (e.g. Brody, 1945; Hemmingsen, 1960; Kleiber, 1975; but also see Heusner, 1982). If Platt & Silvert's prediction for marine mammals were supported by empirical data, it might well have far-reaching implications, given the interdependence of metabolic rate, other components in energy budgets of animal populations (e.g