Sunday, 20 March 2011
POLAR BEAR CLASSIFICATION
Five of the eight species of bears are threatened. There are around 20-25,000 polar bears, of which 15,000 are in Canada. The IUCN Red List, which lists all rare species, describes the polar bear as 'vulnerable’ and efforts are needed to ensure its future.
IUCN = International Union for Conservation of Nature
POLAR BEAR classification
Living things can be organised into different groups. Species that are alike are grouped together. This is called classification.
Family: Ursidae (bears)
Species: Ursus maritimus (polar bear)
Powerful and ruggedly beautiful, the massive and eye-catching polar bear is the biggest species of bear in the world and the symbol of the Arctic. Measuring up to 3.5m, a male polar bear can weigh an incredible 650kg, that’s as heavy as 10 people!
The polar bear is ideally adapted for life in the cold and hostile Arctic. Thick white fur is a great camouflage and with a layer of blubber under the skin, keeps the bear warm. Powerful legs and large paws help it to break through ice and sharp claws enable it to grab its prey – seals, walrus and even small whales. Polar bears can swim for hours aided by a water-repellent coat and webbed feet.
Polar bears are found in the area around the North Pole known as the Arctic Circle. This includes some of the coldest places on earth such as parts of Alaska, Canada, Greenland, Norway and Russia.
The Arctic is an icy cold world. In winter much of the land and water is covered in thick layers of snow and ice. By summer, much of the ice melts and land is uncovered. Polar bears follow the ice floes north or are stranded on the mainland until the sea re-freezes in autumn.
Polar bears are the only carnivorous bear species and almost exclusively eat meat. Their main food source is seals, which they catch by waiting near a crack in the ice for seals to come up for air. Polar bears can survive for several days without food, but if food is scarce will eat birds, berries, rodents and even grass.
Polar bears are excellent swimmers and their webbed feet, hollow hairs and thick layer of blubber are all excellent adaptations for life in cold water. Polar bears stay underwater for a couple of minutes in search of food.
Polar bears tend to live, eat and sleep in the open. Only pregnant females build dens. But if they are caught in a severe storm, polar bears may build a temporary shelter in the snow.
Polar bears are usually solitary except during the breeding season. Every year they travel hundreds of kilometres and may range over an area of up to 250,000km2 in their lifetime
Females mature by four years and after mating build up fat stores over summer. In eight months a 600g single cub or twins will be born, but will weigh 15kg when ready to leave the den at four months old thanks to the mother’s rich milk. A cub stays with its mother until 2½ years old.