They’re Not Really White and 19 Other Fascinating Facts About Polar Bears

They’re not the world’s largest carnivores by a long shot. That honor goes to the squid-eating sperm whale, which can grow to a length of 60 feet and a weight of 80,000 pounds. But on dry (or icy) land, polar bears hold the title, weighing up to 1,320 pounds and stretching as much as eight-and-a-half feet from nose to tail.

Polar bear cubs are tiny at first, not much more than a foot long, and blind and toothless. They grow fast, however, nourished for at least 20 months by their mothers’ very rich milk. It has a fat content of 31% to 35%, the highest of any bear species (cow’s milk is typically only 3% to 4% fat).

Mother polar bears give birth to anywhere from one to three cubs at a time, with twins being the most common. In 2003, Canadian researchers discovered a rare pair of identical twin polar bear cubs.

The shafts of hair on a polar bear are hollow and transparent, but they appear white because the air spaces in each hair scatter light of all colors, and our eyes see white when all visible wavelengths of light are reflected. The skin underneath the hair is actually black.

According to the Polar Bear Specialist Group of the International Union for Conservation of Nature (IUCN), the polar bear population of one of these irregularly shaped and variously sized units, Southern Beaufort Sea, bordering Alaska and Canada’s Northwest Territories, is in decline.

These countries are Canada, the United States (Alaska), Denmark (Greenland), Norway, and Russia. Polar bears are found in areas of these countries that surround the Arctic Circle, representing three continents — North America, Europe, and Asia (far eastern Russia in the latter case).

Some 13 of the 19 sub-populations identified by scientists are found in Canada. These account for 60% of the total global polar bear population.

Polar bears aren’t native to Iceland, but over the centuries at least 500 documented references to them have been published. The animals apparently float over on icebergs from eastern Greenland. In 2008, a working group established by Iceland’s environment minister decided that the intruders should be killed, citing three arguments: they pose a threat to humans and livestock; they come from an area with healthy polar bear stocks that can withstand the loss of a bear now and then; and the cost of rescuing one could be as much as $85,000.

It is estimated that polar bears spend about half their time hunting for food. Though they have a predilection for ringed and bearded seals — seals have a high fat content, which the bears need for survival — they’ll also eat other varieties of seals, whales, walruses, reindeer, small rodents, fish, and human garbage, among other things.

In the summer and fall, when seals spend more time in the water or in areas beyond the reach of polar bears, the bears sometimes resort to cannibalism — typically with large adult males eating cubs or smaller bears. Some scientists believe that the decline in sea ice due to climate change will only make the practice more widespread.

Polar bears get all the liquid they need from the seals and other animals they eat, so have no need to drink water.

It is said that they can smell a seal from 20 miles away, and that a polar bear will walk 100 miles to follow the scent of a female in heat.

In 2008, the polar bear was listed as a threatened species under the U.S. Endangered Species Act. Environmental factors, including the effects of climate change, have contributed to their decline, as well as the bears’ low natural reproduction rate. The global population of the animals is projected to decline 30% by 2050.

Unlike other bear species, polar bears don’t shut down and go to sleep in the winter — nor do they, as was once believed, enter into a state of walking hibernation in which their body temperatures drop.

Polar bears might not settle down for long winter naps like other bear species, but they get plenty of shuteye. Besides sleeping for seven to eight hours each night, they often nap during the day, especially after a meal or a swim or if the weather is too hot or too cold.

Though polar bears can live to the age of about 30 in the wild — 32 is the record — only a small percentage of them make it past 18 years. They tend to do better in captivity, however: The oldest known polar bear in a zoo made it to 45.

Native peoples in areas where polar bears live have traditionally hunted — and eaten — them. (They abide by a quota system, limiting the number of animals they can hunt.) Nathan Myhrvold, the Microsoft chief technology officer and prolific inventor turned cookbook author, sampled braised polar bear meat prepared by a local on a trip to Greenland and noted that “it was coarse textured meat, probably from the leg, and…it was delicious.”

As with seals and walruses, the livers of polar bears contain an exceedingly high dose of Vitamin A. A healthy adult can tolerate 10,000 units of the vitamin; a pound of polar bear liver contains as much as nine million units — so even a small portion can be toxic. Excessive consumption of the vitamin affects the central nervous system, and can cause liver problems, blurred vision, and peeling skin, among other issues, and sometimes even death.

Polar bears are very good swimmers, able to achieve a speed of about six miles per hour. Olympic gold medalist Michael Phelps matched that speed in the 2016 Summer Games, in the 200-meter individual medley. The difference is that polar bears can maintain their speed over long distances. They can cover more than 60 miles at a time in icy water, and a female polar bear was once tracked swimming 400 miles in one go in the Bering Sea, then resting for a few hours before continuing on for another 1,100 miles.

More than 50 polar bears have been roaming the streets of the 2,000-person Russian Arctic military settlement of Belushya Guba since December. Shifts in sea ice due to climate change may or may not be a factor, but the community is scared, and people are staying indoors as much as possible.