Figure 4.
Schematic figure depicting the relationship between ambient temperature and metabolism (black line) and the general thermal responses within the thermoneutral zone, above the upper critical temperature (TUC), and below the lower critical temperature (TLC). For marine mammals in water, evaporative heat loss becomes futile, and diving imposes additional constraints on heat production due to the need to conserve oxygen. Therefore, marine mammals must compensate for these limited modes of heat exchange through vasomotor changes and behavior. Several questions remain to address how diving (and the associated metabolic response, blue line) modulates their thermal responses (represented by the question marks).