Fig. 6. Mean (+S.D.) metabolic rates (the multiple of the basal metabolism predicted by Kleiber's allometric equation; Kleiber, 1975) of seven grey seals during diving (DMR) or during rest (RMR) at the water surface. Resting values are for alert, inactive animals breathing continuously. These data are compared with values for the same individuals, on the same day, during diving. The difference is significant (paired t-test, t=3.86, P=0.003).