Polar bear

The polar bear (Ursus Maritimus) is almost entirely carnivorous, unlike other relatives in the bear family. It is undoubtedly at the top of the food chain in the arctic regions. The diet is mostly ringed seals with the occasional bearded seal thrown in for variety. To hunt seals, the bear waits motionless beside the seal's breathing hole. When the seal surfaces, the bear either bites the head, or swats the seal with its paws, flipping the seal out onto the ice. The bear may also stalk the seals, either in the water or on land, or use its front paws to break through the roof of a birth lair, where a mother seal and her young are. Polar bears will scavenge on carcasses of whales and walruses, and, if seals are in shortage, are known to hunt and feed on reindeer, small rodents, sea birds, and of course humans.

The fact is, polar bears are the most aggressive bears towards humans. Compared to other bears, polar bears are more willing to consider humans as prey. This means that when a polar bear does attack a person, they are not likely to leave until either the person or the bear is dead. Young animals and mothers with cubs are the usual culprits when human attacks have been documented. They're also the chief scavengers (among polar bears) of human dump sites. Both groups tend to be thinner and hungrier; subadults are inexperienced hunters, and females with cubs must feed themselves and their young

Polar bears are amazing swimmers. Their feet are partially webbed, they have long necks to keep their noses out of the water, and they actually float without any effort, due to the amount of fat they store on their bodies. A polar bear usually swims around 3 mph, but is capable of swimming 6 mph for over 10 hours without pausing to rest. Polar bears can also run pretty fast, reaching speeds of 25 mph for short distances.

Polar Bears are huge animals. Males grow to weigh 1100 to 1300 pounds, and females average about 700 pounds. There is a record of one adult male weighing 2200 pounds, over one ton! They generally stand about 3 feet tall at the shoulder and reach a length of 8 to 11 feet. They live about 25 years in the wild, considerably less in captivity.

Polar bears mate in late spring and early summer. Through a remarkable process known as delayed implantation, however, the fertilized ovum doesn't actually attach to the uterine wall until September. The purpose for this is believed to be that if the mother is unable to store enough fat to survive the winter, the embryo will not implant, and will simply be reabsorbed into the mother's body. The mother enters the den in October or November, and the cubs are born in the next two months, while the mother is still hibernating. The cubs, usually 2 or three are about the size of a chipmunk and suckle their mother, who remains asleep until she breaks out of the den in March or April. By then the cubs will each weigh 22 to 35 pounds. What a concept! Go to sleep and wake up with two kids.

Only pregnant polar bears actually hibernate. Other bears will enter a shelter and sleep for a short period of time, but the mothers are the only ones who remain there for a long time. During hibernation, the bear's heart rate will drop from 40-70 beats per minute to about 10 beats per minute. Unlike many animals, however, the polar bear's body temperature only lowers slightly. This high body temperature is important in that it keeps the temperature in the den above freezing for when the cubs are born. The bear passes neither fecal or urea waste during hibernation, but has developed a unique process of recycling the urea into usable proteins. The urea buildup would kill most animals within two weeks.

The polar bear population is now around 30,000 individuals, up from only 10,000 in 1968. The increase is due to government regulations on hunting. There is concern, however, that due to global warming, the southern range of the polar bear is being pushed northwards, and populations may suffer.

The single fact that makes polar bears the most terrifying critters out there in the wilds today is not that they're huge and strong and fast and amphibious and invisible on infrared and not at all averse to preying on humans when there's nothing else around (and there's not much around in the arctic wastelands they call home). No, the scariest thing about polar bears is the following:

On the ice, the only visible part of a polar bear (to the eye and to infrared both) is its black nose. Polar bears know this, and cover their noses with one paw while stalking their prey, rendering themselves completely invisible.
Now that's scary.

The moral of the story? Don't ever mess with a polar bear. Ever. They are more badass than you can ever hope to be (and they just evolved that way, without going to yossarian's school or taking lessons from thefez!) And if you ever see me covering my nose with one hand, know that I'm being polar bear-stealthy at you and be afraid.

Boy, am I in a silly mood. Sorry about that. Go vote up zgirll's excellent factual writeup on these magnificent monsters while you're downvoting me into oblivion.

Note (26 January 2002): Razhumikin, who admits that he has perhaps seen a few too many polar bear documentaries in his day, says the eyes of polar bears are also visible to regular and infrared light both. Still, their eyes are smaller than their noses, and they cover their noses! That's so scary!

Contrary to what some foreign people seem to think, polar bears do not roam the streets of Scandinavian cities. Though they are quite common in Canada and northern Russia they are only sighted in the extreme north of Scandinavia during special conditions. The rim of the polar ice, where the polar bears hunt for seals, usually don't reach Scandinavia.

A place where polar bears is quite common is Svalbard, a group of islands in the northern Arctic Ocean that belongs to Norway. The islands is home to a small Norweigian and Russian mining community, and when visiting places outside populated areas, rifles must be brought at all times. Fences for protection against polar bears have been built around settlements.

But to your next trip to Stockholm, you can safely leave your polar bear-rifles at home.

Polar bear liver (and also seal liver) contains very high levels of Vitamin A in the form of retinol - up to 30,000 IU/gram which is over 45 times the levels found in cow's liver. Because Vitamin A is one of the few vitamins that is stored by the human liver the level gained from eating even small quantities of polar bear liver can cause toxicity. Within hours of eating polar bear liver (a portion contains several million units of Vitamin A) Arctic explorers developed some of the symptoms of Vitamin A poisoning, including drowsiness, irritability, headache and vomiting, with subsequent peeling of the skin and hair loss.

Due to pollutants entering the food chain polar bear liver also contains heavy metals such as mercury and cadmium, and persistant organochlorine insectides (POPs) - the levels increasing with the age of the bear. These chemicals are known carcinogens and also cause congenital birth defects and blood disorders.