The
polar bear (
Ursus maritimus) is a
hypercarnivorous bear whose native range lies largely within the
Arctic Circle, encompassing the Arctic Ocean, its surrounding seas and surrounding land masses. A boar (adult male) weighs around 350–750 kilograms (770–1,650 lb), while a sow (adult female) is about half that size. Polar bears are the largest land carnivores currently in existence, rivalled only by the omnivorous
Kodiak bear. Although it is the
sister species of the
brown bear, it has evolved to occupy a narrower
ecological niche, with many body characteristics adapted for cold temperatures, for moving across snow, ice and open water, as well as for hunting
seals, which make up most of its diet. Although most polar bears are born on land, they spend most of their time on
sea ice. The species's scientific name, which is derived from this fact, means 'maritime bear'. Because of their dependence on sea ice, polar bears are categorized as
marine mammals. Due to expected
habitat loss caused by
global warming, the polar bear is classified as a
vulnerable species. For decades, large-scale hunting raised international concern for the future of the species, but populations have rebounded after controls and quotas began to take effect.
This picture shows a polar bear on an ice floe north of Svalbard, Norway, feeding on a bearded seal.Photograph credit: Andreas Weith