Polar bear on the coast of Svalbard by Kai Müller

Polar bears are the largest predatory species on land. There are rarely single extra large brown bears larger than them and some aquatic predators such as elephant seals. The body size of polar bears varies by region. The smallest occur in the eastern part of Greenland, the largest in the Bering Sea. Body weight also depends on the time of year and the associated nutritional status. Overall, the head-trunk length is 180 to 280 centimeters and the shoulder height is up to 170 centimeters. Male polar bears weigh 300 to 1,000 kilograms, females 150 to 250 kilograms. This makes them one of the mammals with the largest weight difference between the sexes.

Like all bears, polar bears have an elongated, stocky body, a muscular neck, a large head with round ears and a long snout, short, strong legs with large paws, and a short, stubby tail. Compared to other bears, polar bears have a longer neck, a smaller, flatter skull, particularly small eyes and ears, and particularly large, broad paws.

Polar bear dentition counts 42 teeth and resembles that of omnivorous bear relatives more than that of other carnivorous predators such as cats and dogs. The strong canines are used in the fight against rival conspecifics and for killing prey.

The fur of polar bears appears white or pale yellowish and has no other markings. However, both the top hair and the undercoat hair are actually transparent. After a meal, polar bears' fur is often smeared with blood and oily. The top hairs are hollow. This creates an insulating air cushion in the polar bear's fur. The summer coat is shorter than the winter coat. The skin is black. It absorbs solar energy well. Under the skin there is a layer of fat around ten centimeters thick to protect the body temperature in the freezing cold.