The Polar Bear's Amazing Fur

The polar bear is a beautiful, agile creature that roams the land, sea, and ice or the Arctic regions. It remarkably calls the frigid landscape home, and yet the most amazing thing about this creature isn't what it appears to be. In this week's edition of expendablenlightenment, we are going to look at what the polar bear's fur and skin. Is the fur white? What color is it's skin? Can you see one if you use an infrared? Why do some polar bears turn green?

First, the polar bear's skin. Believe it or not, the polar bear's skin is actually black. If you remember from your science classes, the color black will attract more heat than any other color. Any light/heat that makes it to the bear's skin will be absorbed by the black skin. This is part of where the amazing polar bear's ability to survive in the frigid temperatures comes from, but it's not the whole story. The fur is the really amazing aspect of this animal.

The polar bear's fur isn't white, even though it appears to be. The fur is actually colorless (clear). The polar bear has an undercoat and more coarse guard hairs to protect the undercoat, both of which are colorless. But why do we see white? You'd have to go back to an earlier posting of expendablenlightenment to fully understand the next part. The light is scattered by the clear fur, and when the entire spectrum is reflected, then we see white. At first it was thought that their fur was hollow, and while there are air pockets in the fur, it isn't all entirely hollow tubes.

This leads us to the question that has popped up on many trivia websites and quizzes and most people can't fathom if it could be true or not. Can you see a polar bear if you use an infrared camera on it? It seems to defy logic to say no, but the true answer is you can't really see a polar bear using the infrared camera. Why? Because the polar bear is so well insulated (nearly 4 inches of blubber, black skin absorbing heat, and the thick coats of fur) that the beat gives off no heat for you to see on the infrared camera. The only part which would be visible would be the warm breath that it would give off, but the bear itself wouldn't.

Polar bear turning green in Japan, 2008.

The polar bear's fur is trule a wonder of the natural animal kingdom. The fur's color will usually change as it gets older. A nice clean white color when they are younger, and a more yellow color as they age. But what would you call a green polar bear? In the 1970's, researchers started noticing a number of polar bears began to turn green in a number of zoos across the world. It took awhile to figure out why, and the answer is somewhat disgusting. In captivity, polar bears have to deal with conditions they would not find in the wild, such as higher temperatures, higher humidity, and pond water that isn't as clean. The researchers found that this pond water would deposite algae inside the polar bear's fur (remember those hollow air pockets inside the fur?). The higher temperatures and humidity would cause the algae to grow rapidly and would actually change the polar bear's fur to a green. It still sometimes happens, but at least it's known why and how to prevent it even though it still happens to this day.

Bet you didn't know that!