The polar bear is a bear native to the Arctic Circle encompassing the Arctic Ocean, its adjacent seas and land masses. It is the world’s largest bear. Although it is closely related to the brown bear, it has many distinct body characteristics adapted for cold temperatures, for moving across snow and open water, and for hunting the seals. Most polar bears are born on land, but they spend most of their time at sea.
Evolution & Distribution:- According to both fossil and DNA evidence, the polar bear diverged from the brown bear. It is often regarded as a marine mammal because it spends many months at sea. It tends to frequent areas where sea ice meets water, to hunt the seals that make up most of its diet. Biologists estimate the global population of polar bears from 20,000 to 25,000. They mainly inhabit in the territory of Five Nations Denmark (Greenland), Norway (Svalbard), Russia, US (Alaska) and Canada.
Biology:- The polar bear is the largest terrestrial carnivores animal, more than twice of the Siberian Tiger. It shares the title of the largest bear species. Adult males weigh 350–680 kg and measure 7.9–9.8 ft in length. Adult females normally weigh 150–249kg, measuring 5.9–7.9 ft in length. During pregnancy, they can weigh as much as 499 kg. The polar bears’ legs are stocky and the ears and tail are small. However, the feet are very large to distribute load when walking on snow or thin ice and to provide propulsion when swimming. The claws of polar bears are deeply scooped on the underside to assist in digging in the ice. Their 42 teeth help them in their carnivorous diet.
Polar bears are covered by upto 3.9 hide and fur. Their white coat usually yellows with age. They overheat at temperatures above 10 °C. The polar bear has an extremely well-developed sense of smell, being able to detect seals nearly 1.6 km away and buried under 3 ft of snow. The polar bear is an excellent swimmer. It can swim 11 km/hour. When walking, it maintains an average speed of around 5.5 km/h. Although aggressive like brown bears, the polar bears often choose to fight. They rarely attack humans unless severely provoked or hungry.
Diet:- As the most carnivorous member of the bear family, most of the diet of Polar Bear consists of seals. Polar bears hunt primarily when the seals come out of the holes in the ice in order to breathe or to rest. The polar bear can kill an adult walrus, which is more than twice the bear’s weight. They also have preyed on beluga whales, of similar size to the walrus. Polar bears are capable of fasting for up to several months during late summer and early fall, when they cannot hunt for seals because the sea is unfrozen. When sea ice is unavailable during summer and early autumn, they eat a wide variety of other wild foods, including musk ox, reindeer, birds, eggs, rodents, shellfish, and crabs.
Lifecycle and Reproduction:- Polar bears live near about 25 years. Females begin to breed at the age of 4 or 5. Males usually reach sexual maturity at 6 years. Mating of Polar Bears takes place in April and May. Between November and February, cubs are born blind weighing about 0.9 kg. The mother gives the cubs her milk and nurses them for two and a half years.
The polar bear is a vulnerable species. There are 19 recognized subpopulations. Of the 19 recognized polar bear subpopulations, 8 are declining. Unrestricted hunting has raised international concern for the future of the species. Global warming is also a significant threat to the polar bear. Polar bears have long provided important raw materials for Arctic peoples. Hunters commonly used teams of dogs to distract the bear and or shoot it. Almost all parts of captured animals had a use. The fur is used to sew trousers, to make outer footwear; the meat is edible; the fat is used in food and as a fuel for lighting homes; sinews are used as thread for sewing clothes; the gallbladder and sometimes heart are dried and powdered for medicinal purposes. Only the liver is not used, as it is poisonous.