Over the course of six years, U.S. Geological Survey researchers used GPS collars to track 50 long-distance swims made by 20 adult female bears, some of which had cubs with them. The swims that were documented lasted from 17 hours to nearly 10 days and covered between 33 and 427 miles (54 and 687 kilometers) in the southern Beaufort Sea.

Polar bears in zoos have been known to turn green. Concrete floors in their pens scrape against the fur, and the abrasions form tiny holes in their hollow guard hairs, opening a gateway for algae that can live and breed inside.

After feeding throughout the winter, a pregnant female polar bear builds a maternity den in the fall where she will give birth to her cubs and nurse them. She'll emerge with her cubs in the spring and head to the sea ice to find seals--which means up to eight months with no meals for mom, an amazing feat.

Polar bears prefer a method known as still-hunting. The bear uses its excellent sense of smell to locate a seal hole and crouches nearby in silence, waiting for a seal to resurface for air.

The polar bear first debuted in a Coca-Cola print advertisement in France in 1922 and then appeared periodically for the next 70 years. The modern polar bear did not make its debut until the 1993 "Always Coca-Cola" campaign in a television ad called "Northern Lights". Since then, the polar bear has appeared in numerous television and print advertisements becoming one of the most popular symbols of Coca-Cola advertising.

The 42 teeth of a polar bear reflect its highly carnivorous diet. The cheek teeth are smaller and more jagged than in the brown bear, and the canines are larger and sharper.

Polar bears give birth to one to three cubs at a time, but most often birth twins that weigh only 1.3 lbs. This evolutionary adaptation increases the likelihood that at least one cub will survive to adulthood, especially given the harsh and unforgiving conditions found in their Arctic habitat.

The largest polar bear on record, reportedly weighing 2,209 lbs (1,002 kg), was a male shot at Kotzebue Sound in northwestern Alaska in 1960. This specimen, stood 3.39 m (11 ft 1 in) tall on its hindlegs.

Genetic testing has confirmed the existence of polar bear/grizzly bear hybrids known as "grolar bears" or "pizzly bears". The hybrid physically resembles an intermediate between the two species, but as wild hybrids are usually birthed from polar bear mothers they are raised and behave like polar bears.

Mature bears tend to eat only the calorie-rich skin and blubber of the seal, which are highly digestible, whereas younger bears consume the protein-rich red meat.