Polar Bear Scientific name:Ursus maritimus

Polar Bear
Scientific name:Ursus maritimus
Polar bears roam the Arctic ice sheets and swim in that region's coastal waters. They are very strong swimmers, and their large front paws, which they use to paddle, are slightly webbed. The polar bear is a bear native largely within the Arctic Circle encompassing the Arctic Ocean, its surrounding seas and surrounding land masses.
Range and habitat
The natural habitat for the Polar Bear is in the very cold areas of the world. They can be found in the Artic, the U.S. (Alaska), Canada, Russia, Denmark (Greenland), and Norway.
Physical characteristics
It is the world's largest land carnivore and also the largest bearAdult males weigh 350–680 kg  and measure 2.4–3 m (7.9–9.8 ft) in length.[36] Adult females are roughly half the size of males and normally weigh 150–249 kg measuring 1.8–2.4 metres (5.9–7.9 ft) in length.
The polar bear has a more elongated body build and a longer skull and nose. the 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 pads of the paws are covered with small, soft papillae (dermal bumps) which provide traction on the ice.
The polar bear is an excellent swimmer and individuals have been seen in open Arctic waters as far as 200 mi (320 km) from land. With its body fat providing buoyancy, it swims in a dog paddle fashion using its large forepaws for propulsion. Polar bears can swim 6 mph (9.7 km/h). When walking, the polar bear tends to have a lumbering gait and maintains an average speed of around 3.5 mph (5.6 km/h). When sprinting, they can reach up to 25 mph (40 km/h).
Hunting and diet
The polar bear is the most carnivorous member of the bear family, and most of its diet consists of ringed and bearded seals.Their main source of food for polar bears is the various species of seals.
The polar bear's most common hunting method is called still-hunting:[56] The bear uses its excellent sense of smell to locate a seal breathing hole, and crouches nearby in silence for a seal to appear.
These powerful predators typically prey on seals. In search of this quarry they frequent areas of shifting, cracking ice where seals may surface to breathe air. They also stalk ice edges and breathing holes. If the opportunity presents itself, polar bears will also consume carcasses, such as those of dead whales. These Arctic giants are the masters of their environment and have no natural enemies.
Reproduction
Mating take place on the sea ice in April and May, when polar bears congregate in the best seal hunting areas. Partners stay together and mate repeatedly for an entire week; the mating ritual induces ovulation in the female.
After mating, the fertilized egg remains in a suspended state until August or September. During these four months, the pregnant female eats prodigious amounts of food, gaining at least 200 kg and often more than doubling her body weight.
When the ice floes break up in the fall, ending the possibility of hunting, each pregnant female digs a maternity den consisting of a narrow entrance tunnel leading to one to three chambers.
Between November and February, cubs are born blind, covered with a light down fur, and weighing less than 0.9 kg.  On average, each litter has two cubs. The family remains in the den until mid-February to mid-April, with the mother maintaining her fast while nursing her cubs on a fat-rich milk. By the time the mother breaks open the entrance to the den, her cubs weigh about 10 to 15 kg. For about 12 to 15 days, the family spends time outside the den while remaining in its vicinity.
Young cubs live with their mothers for some 28 months to learn the survival skills of the far north. Females aggressively protect their young, but receive no help from their solitary male mates. In fact, male polar bears may even kill young of their species.
Predatory
Humans are the polar bears only predator.Polar bear are apex predators at the top of the food chain. However, babies are severly threatened by a number of predators.
Life expectancy
  The wild polar bears live up to age 25.