Aspects of temperature regulation in harp seal pups evaluated by in vivo experiments and computer simulations

Temperature regulation in harp seal pups (Pagophilus groenlandicus) has been studied by in vivo measurements of oxygen consumption, body temperatures and in vitro determinations of the thermal values of a fur sample. The experimental animals were restrained and exposed to natural wheather conditions. Solar irradiance above 600 W/m (global radiation) caused hyperthermia. Computer simulations based on the thermal values of the fur indicated that heat dissipation from primarily the limbs is a prerequisite for avoiding hyperthermia under natural weather conditions. Further simulations showed that the lower critical temperature of a lean newborn harp seal pup with standard metabolism is only--1 degree C while it is depressed to--59 degree C as the pup grows, aquire a 10 cm thick layer of blubber and the metabolism increases to 1.5 times standard. High metabolism and tolerance to low deep body temperatures (35 degree C) seems a prerequisite for thermal balance in the harp seal pup under cold conditions.