Temperature of Skin in the Arctic as a Regulator of Heat

Abstract

Arctic birds and mammals maintain ordinary body temperature with normal metabolic rate at air temperatures 10 -90 C degrees below body temperature. Heat loss during exercise thus becomes a problem. Escape of heat through bare or poorly insulated extremities is an important avenue of heat loss used by these animals. Heat conservation is also effected by ability of these parts to tolerate low tissue temperatures, thereby avoiding costly heat loss. Dogs, wolves, caribou, bears, porcupines and other mammals have, respectively, noses and faces, legs, and foot pads that belong in this category of poorly insulated and cold parts. Gulls, ducks, and geese have bare legs which are immersed in cold water for long periods. With iron-constantan thermocouples used in conjunction with potentiometers temperatures of rectum, subcutaneous tissues, and skin surface were measured in cold. Central body temperatures did not vary over 2 degrees; skin temperature was not more than 10 degrees lower than central body temperature, usually less; but temperature in cold extremities might be 40 degrees below central body temperature and near 0 degrees. The variability of reduced temperature in the parts involved, such as along the leg of a caribou, is depicted. Methods for conservation and dissipation of heat from these parts, such as vascular heat exchangers, are discussed. The importance of these parts to the metabolic economy of the animal are outlined.