Article: Polar Bears Print

polar-bear-head-300Polar bears are amazing – and we’re not talking about fictional armored polar bears now. These incredibly huge, majestic animals live in some of the most extreme conditions on Earth. Imagine living in temperatures that can plunge as low as -50°F! Polar bears have evolved over time to withstand the bitter cold of the Arctic. Just by sight alone, you can see several adaptations. Most obvious is the polar bear’s color, which can range from a butter cream yellow to a very pure white. Appearing white like its surroundings provides a natural camouflage for the polar bear. But, interestingly, appearances can be deceiving. Polar bears aren’t actually that color – their skin is black.

You know how it’s warmer for you to layer clothing on a cold day – well it’s the same for a polar bear. Two coats cover a polar bear’s black skin to insulate it from the cold. There’s a colorless, soft, fuzzy undercoat of fur, which rests against the skin. And on top of the undercoat, is a thick covering of long, stiff guard hairs, which also are colorless – like tiny, clear plastic straws. The fur only appears white because it reflects visible light, much like the snow and ice that surround the polar bear. The undercoat traps air next to the skin, while the guard hairs help to repel water. There’s another layer of protection that you can’t see. A thick layer of blubber ranging from one or two inches to four and a half inches sits just beneath the skin, covering all the bear’s muscles. Blubber is a layer of stored-up fat that acts as a blanket to hold in the bear’s body heat. It can also be a source of stored up energy if the bear ever finds itself without an immediate food source.

Another adaptation that has helped the polar bear survive the cold is the size of its ears and tail. If you’re wondering how that works – it’s pretty simple. A bigger tail and ears would mean more surface area, which means a larger area susceptible to heat loss. Small ears and a small tail reduces the surface area, thereby minimizing the heat loss. OK, so you’re probably thinking with that reasoning, then a polar bear should have some pretty small paws. Not so. And that’s because the benefits of big paws considerably outweigh the heat loss thing.

Large paws, measuring up to one foot across, support and help distribute the polar bear’s impressive heft across the ice. Its black footpads are dotted in tiny bumps called papillae. The papillae along with thick tufts of fur, which surround the bear’s toes and footpads, and short, strong claws give much needed traction. As you can see, a polar bear’s paws are essentially snow shoes! Try walking on ice all day, every day without a pair. And, it turns out the paws are a bit like a pair of cross trainers, too – but instead of switching from basketball to running in a split second, they go from snowshoe to a paddle and rudder for swimming.

Super Senses
polar-bear-head-300A polar bear’s eyesight and sense of smell must be strong. Reportedly, a polar bear can smell a seal up to 20 miles away! Their teeth are different from other bears because their diet is different. For example, brown bears mostly eat vegetation, while polar bears mostly eat other animals – primarily the ringed seal. Watching a polar bear “hunt” a seal is a lot like watching someone go ice fishing. Except there’s no warm hut and hot cocoa. Ringed seals spend a lot of time in the water, under the ice. They’re hunting for their own food. But, they have to come up for air a lot. So, they’ll have a bunch of breathing holes scattered around the ice, so that they can pop up for a bit of fresh air before returning to the hunt. These breathing holes are a polar bear’s natural fishing – well in this case sealing – spot.

A polar bear will stretch out by a breathing hole and wait for a seal to surface. When it does, the polar bear will swiftly swat the seal and essentially hook it with its claws. Sometimes seals are out of the water, hanging out on the ice. Polar bears can easily sneak up on a group of sunning seals and pounce on the unsuspecting prey. Surprisingly, the bears aren’t going straight for the flesh, but rather the skin and blubber of the seal. It provides a lot more energy. Like us, it seems that polar bears like a little variety in their diet. Beluga whales, hooded seals and walruses sometimes make the menu. Polar bears also eat kelp (a type of seaweed), fish, sea birds, and mussels. And like their brown bear relatives, some polar bears – depending on where they live – will forage for berries in the fall.

polar-bear-swimming-300Polar bears belong to the genus and species Ursus maritimus, which means, “sea bear.” The term sea bear is appropriate because, as you now know, polar bears depend on the sea for much of their diet. Besides weathering extreme temperatures on land, polar bears go extreme off land, too. In fact, many polar bears spend a great amount of time in the water and on ice floes. Not only have their coats and paws evolved to help make them good swimmers, their body shape has, too. A polar bear’s body is more elongated and streamlined for swimming – they’re missing the shoulder hump of the brown bear. And, its neck is longer, which helps keep the polar bear’s head above water. Polar bears can swim approximately four to six miles per hour and have been spotted pretty far out to sea – as much as a few hundred miles from shore or even an ice floe.

Right now, estimates for world population of polar bears is somewhere around 25,000 to 27,000. But, because of global warming, scientists believe that number could be drastically different by 2050. Some say the population could decrease by half and others argue it could be diminished by two-thirds. Global warming is causing areas of sea ice to shrink and even disappear. If the projected estimates are true, by 2050, there will be no polar bears living in the wild at all in the United States.

Discover More