Polar bears could be called “ice bears” because they spend most of their lives wandering on Arctic sea ice in search of seals. Unlike grizzly bears, they spend little time on land.
Polar bears and grizzly bears: distant cousins
Scientists believe that polar bears evolved from grizzly bears between 70,000 and 150,000 years ago. The bears became supremely adapted to life on sea ice: their fur is white with water repellent guard hairs and dense under-fur. The white fur helps to camouflage polar bears as they stalk seals resting on the edges of ice shelves.
Polar bears’ relatively short furry snout and small ears are less likely to get cold than the longer noses and ears of grizzlies. These northern-most bears have big paddle-like feet with short, curved claws that are suitable for both swimming and walking on ice and snow, and are much less effective at digging than long grizzly claws. Grizzly teeth and polar bear teeth are also different: polar bear molars are better suited for chewing meat while grizzly molars are flattened for grinding vegetation. Large male polar bears have weighed over 1,400 lbs and measured over 9 feet from nose to tail. By contrast, male grizzlies in the Lower 48 can weigh up to 800 lbs and measure up to 7 feet.
To learn where polar bears live, what they eat, and why they are threatened, see the links to the right.