北极熊

Polar bears are capable of interbreeding with brown bears and producing fertile hybrids — polar grizzlies.
The polar bear is the largest land carnivore among mammals of the order Carnivora. Its length reaches 3 m, and its weight can reach up to 1 t.
The smallest polar bears live on Spitsbergen, while the largest inhabit the Bering Sea. Females typically weigh 200–300 kg.
The ice bear has well-developed senses of smell, hearing, and vision — it can spot prey several kilometers away and detect a ringed seal from a distance of 800 meters.
The polar bear, the most carnivorous of all bears, in spring and summer, when coming to the shore, selectively eats fish and objects washed up by the sea.
Under ultraviolet photography, the polar bear appears dark because its fur absorbs ultraviolet rays.
The polar bear obtains a large amount of vitamin A from its prey, which accumulates in its liver. There have been cases of poisoning in people who consumed polar bear liver.
The ice bear can run at a speed of up to 40 km/h, despite its large mass and apparent clumsiness.
The ice bear lives up to 25–30 years, and in captivity its lifespan can reach 45 years.
The polar bear catches its prey by striking it with its paw, pulling it onto the ice when the animal sticks its head out of the water.
The fur is actually transparent and the skin is black.

年龄

Ice bears have a typical lifespan of from 20 to 30 years, with a maximum recorded lifespan of 43 years and 10 months, and a theoretical lifespan ranging from 21 years and 11 months to 43 years and 10 months. The species reaches sexual maturity between 4 years and 9 months and 8 years of age. The eyes open between 4 weeks and 1 month and 2 weeks; during the "embryo" stage, the embryo develops inside the mother, which includes a period of delayed development after fertilization. The "cub" stage begins when the young are born very small and helpless, living with their mother in a den and feeding on milk for a duration of from 1 day to 2 years and 6 months. Following this, the "adult" stage commences, lasting from 5 to 25 years, during which the adult lives independently, hunts, and can reproduce.

表型

The young ice bear has white, thick fur that appears soon after birth and protects it from the cold; the adult white bear also possesses thick white fur which retains body heat and camouflages the animal among snow and ice. A thick layer of fat under the skin protects the species from severe cold and serves as a food reserve. The adult has large, sharp claws that aid in walking on ice, swimming, and hunting prey, and its wide paws with fur on the soles allow it to avoid sinking into ice and swim quickly.

生理学

Ice bears have a body height ranging from 1.5 to 3.5 meters and a body length ranging from 1.8 to 3 meters; the species’ mass varies from 165.84 to 171.34 kilograms. The embryonic stage exhibits a body mass between 1 and 10 grams and a body length between 0 and 1 millimeter. During the juvenile stage, the young have a body mass ranging from 0.6 to 100 kilograms and a body length from 20 centimeters to 1.4 meters. An adult ice bear has a body mass between 150 kilograms and 0.4 metric tons, with a body length ranging from 1.8 to 2.5 meters.

栖息地

The ice bear inhabits several distinct biomes, including shallow coastal waters where crabs reside, the open ocean with large whales and sharks, polar seas that are nearly always covered in thick ice and are very cold, nearly polar seas that are ice-covered or have ice floes for most of the year and experience very cold winters, and taiga forests characterized by a cold winter and coniferous trees such as spruce and pine. The species’ landscape includes marine environments, coastal waters, and the nearshore zone along the seabed. The climate varies across its habitat, encompassing polar tundra with short summers and abundant moss, extremely cold conditions with significant snow and ice, snowy winters, and tundra characterized by very cold temperatures, a short summer, sparse vegetation, and plentiful moss. The species’ elevation ranges up to 100 meters above sea level.

庇护所

The ice bear is found on shore or on sea ice, and utilizes dens as shelters. These dens are constructed from snow, serving multiple purposes including hibernation, reproduction, and protection from cold temperatures.

地理

The polar bear occupies the Nearctic realm, the Palearctic realm, and the marine realm; the species is found in the Russian Arctic desert, the Beaufort Sea, and the Chukchi Sea ecosystems.

食性

The ice bear hunts seals near breathing holes in the ice, using its paw to strike or seizing prey with its teeth, and occasionally consumes carrion and fish. Its diet includes ringed seals, hooded seals, walruses, carrion, fish, and large mammals. The species employs hunting strategies such as active pursuit, ambush, foraging, and chasing. The daily food requirement ranges from 1.5 kilograms to 5 kilograms; young ice bears feed exclusively on milk. Prey items include geese, reindeer, narwhals, ringed seals, and walruses. Some cultures consume the animal, though it is not considered halal or kosher.

繁殖

The species develops from an embryo that takes 2 months and 1 week to develop. Mating occurs in spring, and the female gives birth to one or two cubs in winter within a den hidden in an underground burrow. A litter has 1 to 3 cubs, and the young are born live on land. The mother feeds and protects the cubs for more than 2 years. The interval between reproduction is from 2 years and 1 month to 4 years. Eggs or young develop in a nest built on land or close to it, and this nest is hidden in an underground burrow where only the mother demonstrates parental care. The species inhabits and develops on land, outside of bodies of water. Sexual reproduction is homogamy, always involving fertilization without generational change. Maturity is reached from 4 to 8 years.