Learn More How Hibernation Works What does global warming have to do with the decline in the polar bear population? How North Pole Expeditions Work

Polar bears have captivated humans since the beginning of recorded time. Writings dating back to 57 A.D. in ancient Rome describe flooded amphitheatres where polar bears and seals were pitted against each other (not much of a fight, as it turns out). Kings of ancient Egypt and early Norway were the first to keep polar bears captive, and the fascination with them has held through the centuries [source: Polar Bears International]. A terrifying version of the animal inexplicably shows up on a tropical island in the TV series "Lost." Ad campaigns all over the world feature polar bears to sell everything from bottled water to transportation systems to soda.

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The iconic polar bear has fascinated people for millennia. This mother bear and her cubs prowl the snowy ground of Manitoba.

Polar bears' shocking whiteness, ferocity and sheer size make them icons of purity and power. Males can grow up to 10 feet tall and weigh up to 1,700 pounds. A single bear can take on a 2,500-pound walrus, and hang onto the massive catch with 2-inch claws. They walk hundreds of miles across ice sheets every winter, following their prey.

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Take the quiz This century may be the last for the polar bear. How much do you know about their plight? Check out this quiz from Animal Planet: On Thin Ice Quiz

­In the Arctic, polar bears are at the top of the food chain, and it's not just because of their size. They're so well-adapted to their environment that they experience no change in body temperature at -34 degrees Fahrenheit (-37 Celsius). However, the incredible survival mechanisms that let them thrive in frigid winters may prove to be their undoing. Because of global warming, winters are getting less cold and polar bears are dying. Scientists project that if climate trends continue, polar bears could be extinct by 2050 [source: Polar Bears International].

What's life like for an animal that needs such extreme cold to survive? Let's head to the Arctic and see how polar bears live on the ice.

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