Sam DeMaria, age 14, of Omaha, Neb., for his question:

ARE POLAR BEARS BECOMING ENDANGERED?

A full grown polar bear may weigh about 1,000 pounds and measure over nine feet in length. He lives in the far north on the Arctic shores of Alaska, Canada, Greenland and Siberia.

The polar bear is covered with a warm, dense coat of white fur that has a tinge of yellow. The color makes the bear hard to see against the background of snow and ice, so he is usually able to crawl toward a resting seal which he kills for food. He's a powerful swimmer, too.

Since the early 1600s hunters have killed thousands of polar bears to obtain the valuable fur. The animal was also bothered by the human invasion in the Arctic area in search of minerals and oil.

By 1973 polar bears had become so threatened that Canada, the United States and Russia, as well as several other nations, signed an agreement prohibiting most commercial and recreational bear hunting.