Miriam Stark, age 12, of East Lansing, Mich., for her question:
HOW CAN A POLAR BEAR LIVE WHERE HE DOES?
The polar bear is at home in the far north, where the shores dip their toes into the icy Arctic Ocean. Sometimes he wanders far inland or swims out to sea. This great white hunter is all set to cope with the worst winter weather. And a spell of mild summery weather tends to make him uncomfortable.
Everything about the polar bear's body is designed to cope with the long cold Arctic winter, with slippery ice and icy sea water. His shaggy white coat is tinged with yellow, and after a swim he shakes himself like a dog to shed the water. Under this water repellant topcoat is an undercoat of thick warm fur.
He has a layer of insulating fat under his skin to hold in his body warmth. In the adult male, this fatty layer may be three inches thick. He is, of course, a warmblooded mammal with a built in thermostat to convert energy into body heat. And his personal thermostat is set rather high. His normal body temperature is 99.6 degrees. If your temperature gets this high, you have a slight fever.
Fur, fat and body temperature keep the polar bear warm when the Arctic winter is at its worst. His wide paws are padded with fur so he can walk comfortably over the slippery ice. Though the big fellow looks rather clumsy, he can gallop along at 18 miles per hour. He also can crouch comfortably while he selects a sleeping seal for his dinner.
Sometimes he prefers a fish dinner. He dives like an expert into the icy water and uses his strong front paws to swim. His fatty rear end is quite buoyant and floats along behind. He can swim at 6 miles per hour, and people have seen him 200 miles from shore.
Obviously the polar bear can .live comfortably through the Arctic winter. He does not hibernate, though he may spend some time in a winter snow den. When spring comes, he wanders south and grazes on the young green grasses. But to him, the mild spring weather feels like a dreary heat wave.
A polar bear cub is born in a snow den, when mid winter gales howl down from the North Pole. The helpless babe is 12 inches long and weighs 1 and 1/2 pounds. But his loving mother is there to feed him and keep him warm. He stays with her for 10 months, learning how to hunt and protect himself. By this time he may weigh 300 pounds and, barring accidents, he can expect to enjoy life in the frozen north for about 33 years.