TEMPERATURE REGULATION IN NEWBORN POLAR HOMEOTHERMS

Although notorious for a hostile climate, the polar regions impose different degrees of thermal stress on the young of the different species that inhabit these areas. This is partly due to wide differences in the time and location for birth or hatching, but the great difference in parental care of the offspring is also an important factor. Some are born immature in tents, dens, or nests and are completely dependent on maternal care during their first period of life. Such forms only slowly develop thermal independence and often pass through an initial stage of hypothermia. Others are born or hatched unsheltered in a more mature state on the barren tundra, on ice floes during midwinter storms, or even in the cold polar seas. Such animals exhibit high metabolic rates and only need high-energy food from their parents in order to get through. Thus, the newborn polar forms show a variety of mechanisms for thermal protection that invite investigation. Unfortunately, such creatures are difficult to obtain for sophisticated physiological studies and few reports on the topic are available at the moment.