The Arctic’s top land carnivore still depends on melting sea ice
Polar bears (Ursus maritimus) are the largest living bears and land carnivores by mass—adult males 300–800 kg—and can interbreed with brown bears. Marine mammals by dependence on sea ecosystems, they hunt seals from annual ice and haul onto land when summer melt opens water.
The polar bear, Ursus maritimus, lives in and around the Arctic and is the largest living bear and land carnivore by weight, with adult males reaching 300 to 800 kg and females much smaller. Its fur is white or yellowish over black skin and a thick layer of fat. Compared with its close relative the brown bear, with which it can interbreed, it is slimmer, with a narrower skull, longer neck, smaller shoulder hump, sharper meat-cutting teeth and big paws for crossing ice and paddling.
Because it depends on the sea, it counts as a marine mammal. It prefers annual sea ice and comes ashore when summer melts it. Its main prey is seals, especially ringed seals, taken by ambush while stalking on ice or in water or waiting at a breathing hole; it mostly eats the energy-rich blubber, and also takes walruses, belugas and some land animals. Bears are usually solitary, though they gather on land, and males guard females in the breeding season. Cubs are born in winter dens and stay with their mothers for up to two and a half years.
Thomas Pennant gave it its English name in 1771. Between the 13th and 18th centuries Europeans called it the white bear, ice bear, sea bear or Greenland bear, the Norse said isbjorn and hvitebjorn, and the Inuit call it nanook. Netsilik speakers even have separate words for adult males, pregnant females, newborns and dormant bears. Linnaeus filed it under the brown bear in 1758; Constantine Phipps described it as its own species in 1774 after sailing toward the North Pole. Some taxonomists placed it in a separate genus, Thalarctos, but fossils and hybridisation keep it in Ursus.
The IUCN rates it vulnerable, with 22,000 to 31,000 animals. Climate change is shrinking sea ice, cutting access to seals and raising the risk of starvation while pushing bears ashore into conflict with people; pollution and energy development add pressure. It has long been hunted for fur and meat and features widely in art, folklore and religion.
Source: Polar bear
