Evaporative heat loss in the California Sea Lion and Harbor Seal

Abstract

1. 1. Total evaporative heat loss was measured in four California Sea Lions and one Harbor Seal at air temperatures between 13 and 30°C. The total heat loss was partitioned into respiratory and cutaneous components. 2. 2. Thermal polypnea was not observed to occur in any of the animals and respiratory evaporative heat loss was estimated to represent less than 3 per cent of the heat production when the animals were hyperthermic in a hot environment (31°C). 3. 3. Active sweating was noted on the bare skin of the flippers of the sea lions but not on the haired surface of the torso. The total cutaneous evaporative heat loss accounted for approximately 16 per cent of the heat produced by metabolism, in a hot environment. 4. 4. It was concluded that evaporative heat loss mechanisms were relatively ineffective in California Sea Lions and in the Harbor Seal also.