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POLAR BEAR





They might not look it, but Polar bears are very similar to the brown bears found in warmer parts of the world- they're called 'sister species'. But because they live in the very northern part of the planet called the Arctic Circle, where it's freezing cold, Polar bears have adapted or evolved to survive there. Their bodies and fur are amazing because they're so good at keeping the Polar bears warm - they insulate them, just like the clothes that humans wear when they go to very cold places.

First of all, they have ten centimetre thick layer of a special kind of fat called 'blubber', which keeps the heat in, and then they have two different layers of fur- a very tightly packed layer at the bottom, and an outer coating of bigger 'guard' hairs.

Believe it or not, the skin of a Polar bear, hidden under it's fur, is black! And the fur itself isn't white! Each hair is a hollow transparent tube, with no more colour or pigment to it than glass. But because of the way it reacts with the light, it looks white to our eyes, a bit like the way the tiny see-through ice crystals we call snow look white when they're all piled up close together.

Humans have developed special cameras that can see heat, called infra red detectors. But because Polar bears keep all their heat so well inside, they're almost invisible when looked at with one of these cameras!

They're carnivores, and eat mostly seals. Their sense of smell is really good, so much so that they can detect the breath of a seal up to a mile away.

They hunt by waiting in a crouching position near a hole in the ice, sometimes for hours, waiting for a seal to pop it's head up - and then they pounce!

There are some great Polar bear facts here -
http://www.animalfactguide.com/animal-facts/polar-bear/

Although there aren't any animals in the Arctic that hunt Polar bears, there is one species of animal that is a threat to their survival - humans!

Because of the burning of fossil fuels like oil and gas, humans are changing the world's weather, increasing the temperature of the whole planet! This is what 'global warming' means. As the planet gets warmer, the ice that the Polar bears live on starts to melt and disappear, causing them lots of problems getting enough food to eat, or safely raising babies, and so the number of them in the world gets less and less each year.

It's hard to imagine that the way humans behave every day, with how they produce their heat and energy, can hurt the Polar bears thousands of miles away, but it's true! This is why human scientists and environmentalists say we need to find better ways of generating power that won't change the weather and warm the planet.

You can find out more about global warming and how it can be stopped here -
http://climatekids.nasa.gov/big-questions/