africanlioness: How thick is a polar bear's fur (how many hairs per square inch)?
Peter Gros: Polar bears have around one million hairs per square inch, similar to a sea otter. Humans have about 20,000 per square inch on their heads. The fur is so important to the polar bear's survival, not just as insulation but also as perfect camouflage as it stalks its prey on the ice flows. Stiff hair grows on the soles of its paws that not only insulate but provide excellent traction on the ice.

africanlioness: Are polar bears born with black skin or do they develop it as they grow older?
Peter Gros: Their skin gets darker as they grow, originating at the base of the hair shaft. Their fur appears white rather than transparent for the same reason as clouds; water foam causes reflection and dispersion of visible light. The fur absorbs ultraviolet light. The coat can insulate the bear to the point where they over-heat at temperatures above 50 degrees Fahrenheit; this is why you see polar bears in zoos with chilled cooling pools and refridgerated enclosures.

lionesspride: How slow/fast is the metabolism of a polar bear? It must be pretty slow if they only manage to catch their prey less than 2 percent of the time.
Peter Gros: It appears that they can alter their metabolism during periods of food depravation at any time of year. Unlike other bears, they can shift as needed into a hibernation-like metabolic pattern when confronted with periods of food shortage. This ability makes polar bears the most advanced of all mammals when it comes to dealing with food and water depravation (Nelson, 1987).

It is true that they often miss catching their prey. On the other hand, catching an adult ring seal or a walrus means they can gorge themselves with hundreds of pounds of fat and go long periods of time without eating again.

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