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Polar bears (Ursus maritimus) are the world's largest terrestrial carnivores. They are specially adapted for life in the Arctic, where they rely on sea ice for hunting, traveling, breeding, and raising their young. Their range extends across the northern polar regions, including areas of Alaska (United States), Canada, Greenland, Norway, and Russia. Their range is limited to areas in which the sea is ice-covered for most of the year. Polar bears have several physical adaptations that help them survive in one of the harshest environments on Earth. Their thick,
water-repellent outer fur covers a dense undercoat. A thick layer of body fat helps protect them from the frigid temperatures. Their fur may appear white or yellowish, allowing them to blend with their surroundings. However, their skin is black, allowing them to absorb heat from the sun. Fur covers nearly the entire bottoms of their large, slightly webbed paws, providing insulation, and traction on ice, Polar bears have longer necks, narrower heads and smaller ears compared to other bears. They have large feet to help them swim and walk on thin ice.
Adult males typically measure 8-10 feet (2.4-3 m) long and weigh between 600 and 1,200 pounds (270-545 kg), although exceptionally large individuals can exceed 1,700 pounds. The largest polar bear ever recorded was a male weighing approximately 2,210 pounds (1,002 kg). Adult females are smaller, generally measuring 6-8 feet (1.8-2.4 m) long and weighing 400-700 pounds (180-320 kg). Polar bears are highly specialized hunters, feeding primarily on ringed seals, although, they also prey on bearded seals and occasionally walruses and beluga whales. They often wait patiently beside seal breathing holes or break
into snow-covered seal dens to capture adults or pups. They may also hunt seals that are resting on the ice. When seals are scarce, polar bears may feed on marine mammal carcasses, birds, fish, eggs, small mammals, berries, and vegetation. Their extraordinary sense of smell allows them to detect prey or carcasses from many miles away. With their slightly webbed paws, polar bears are excellent swimmers and can travel thousands of miles each year by swimming, and walking across shifting sea ice. They primarily use their large front paws for paddling while their body fat
provides buoyancy. Seasonal movements are closely tied to the formation and melting of sea ice, which they depend upon for access to seals. As sea ice melts during summer, many bears follow the remaining pack ice northward, while others spend time on land until new ice forms in fall. Polar bears are generally solitary animals except during the breeding season or when females are raising cubs. Breeding occurs between March and May. After mating, the development of the fertilized egg is delayed and the egg does not implant in the female's uterus until about late September. Once the embryo begins to grow, the gestation period is only about
2-3 months. In October or November, pregnant females dig snow dens, often along riverbanks, coastal bluffs, or sea ice where deep snow has accumulated. These dens provide protection and remain well insulated from the elements, with interior temperatures that can be up to 40°F (22°C) warmer than the outside environment. Cubs are usually born in December or January, with twins being the most common litter size, although one to three cubs may be born. Newborn cubs weigh only 1-2 pounds (0.5-1 kg) and are about 12-14 inches (30-36 cm) long. They
remain inside the den until March or April, when they weigh approximately 20-25 pounds (9-11 kg). Mothers are extremely protective and care for their cubs for a little over two years before breeding again. Young cubs may face danger from adult male polar bears, which sometimes kill cubs. Polar bears typically live 25-30 years in the wild. They occur in 19 subpopulations throughout their range. As of 2023, the global population is estimated at approximately 26,000 individuals. Polar bears are mostly protected from hunting. Their fur is still used by Alaska
Natives to make clothing and blankets, which help them survive bitter cold temperatures. Today, the greatest threat to polar bears is trending warmer temperatures causing a loss of sea ice. Because polar bears depend on sea ice as a platform for hunting seals, feeding, reproducing, and traveling, the decline of Arctic sea ice reduces their ability to obtain enough food and threatens the long-term survival of many populations. For more marine facts, click the SUBSCRIBE button!
