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The polar bear (Ursus maritimus) is a large bear native to the Arctic and nearby areas. It is closely related to the brown bear, and the two species can interbreed.The polar bear is the largest extant species of bear and land carnivore, with adult males weighing 300–800 kg (660–1,760 lb).
The key danger for polar bears posed by the effects of climate change is malnutrition or starvation due to habitat loss.Polar bears hunt seals from a platform of sea ice. Rising temperatures cause the sea ice to melt earlier in the year, driving the bears to shore before they have built sufficient fat reserves to survive the period of scarce food in the late summer and early fall.
Because of its cold temperature, much of the Earth's water comes from the polar regions. 90% of the world's water comes from the Antarctic ice cap although a lot of this water is not used. [11] Water environments are important for many species around the world. Many bacteria thrive there as well as algae and flora. Many of the ponds or lakes in ...
Polar bear in Manitoba, Canada. November 2004. Polar seas is a collective term for the Arctic Ocean (about 4-5 percent of Earth's oceans) and the southern part of the Southern Ocean (south of Antarctic Convergence, about 10 percent of Earth's oceans). In the coldest years, sea ice can cover around 13 percent of the Earth's total surface at its ...
In contrast, the polar bear is mostly terrestrial and only go into the water on occasions of necessity, and are thus much less adapted to aquatic living. The diets of marine mammals vary considerably as well; some eat zooplankton , others eat fish, squid, shellfish, or seagrass, and a few eat other mammals.
Although polar bears spend most of their time on the ice rather than in the water, polar bears show the beginnings of aquatic adaptation to swimming (high levels of body fat and nostrils that are able to close), diving, and thermoregulation. Distinctly polar bear fossils can be dated to about 100,000 years ago.
There are an estimated 17,000 polar bears across Canada; of the world’s total estimated population of 26,000. A polar bear and a cub search for scraps in a large pile of bowhead whale bones (AP)
The 1958 Statehood Act set up a program for polar bear management, and further conservation efforts, including the 1972 Marine Mammal Protection Act, have limited polar bear hunts. [10] Polar bear populations may be threatened by oil development and global warming. [10] [11] Only about 4700 polar bears are known to inhabit Alaska. [12]