bears are superbly insulated by their 10 cm (3.9 in) of blubber,
their hide and their fur. Their insulation is so efficient that
overheat at temperatures above 10 °C (50 °F).
bear fur consists of a layer of dense underfur and an outer layer
of guard hairs, which appear white to tan but are actually transparent.
Unlike other Arctic mammals, they do not shed their coat for a darker
shade to camouflage themselves in the summer conditions. As oils
leech out from the skin, the coat will tend to yellow with age