BIOMECHANICAL ANALYSIS OF FUR AS A TOOL FOR THE STUDY OF THERMAL INSULATION IN SEMI-AQUATIC MAMMALS

One of the means for body insulation in mammals during their transition from terrestrial to semi-aquatic and then aquatic life is based on the usage of fur in water as an effective "dry" insulator. Fur functional conditions are changed drastically and instantaneously when fur contacts with water. The physical mechanisms underlying fur waterproofing were analyzed and their relations to both fur structure and animal body size established. The results of the analysis allow us to define to what extent the fur structural features of a mammal in relation to its body size are capable of trapping an insulative air layer when the animal swims in water. Based on our analysis, both the body size of the ancestors of fur seals and the type of thermal insulation changing in the postnatal ontogeny of sea bears are hypothesized.