I recommend the book 'Arctic Dreams' by Barry Lopez. It has alternate chapters on the exploration and widlife of the Arctic.

Of the chapter entitled Tornassuk I recall that the hairs of a polar bear's pelt are hollow, and bears go green in captivity because these are invaded by algai. Also that they lose heat through the soles of their paws, leaving 'hot' footprints, so can be tracked from the air with infra-red cameras.