Welcome to The Sound of Science on WNIJ. I’m Jeremy from NIU STEAM and today I’m joined by Ann.
In this episode we’ll be answering a question from our listener Kylee M. Kylee wants to know why polar bears are white.
Oh, that’s easy. Polar bears aren’t white.
Excuse me?
Polar bears look white, but they aren’t.
Do you mean their fur is white, but their skin is a different color?
Well, you’re right that their skin isn’t white. It’s actually black! But, their fur isn’t white either.
Okay, then what color is their fur?
A polar bear’s fur doesn’t have any color. In fact, polar bears have two coats of fur, both of which are made of hairs that are hollow and clear. Sunlight scatters and reflects off of these hairs, creating the appearance of white fur. But if you look at the actual hairs, there’s no white pigment, they’re clear.
So why do some polar bears look as white as snow and others seem to be a little bit more yellow?
A yellow polar bear is usually a well-fed polar bear. If a polar bear’s coat looks yellow, it’s usually due to higher concentrations of oil that they get from consuming seal meat.
And when polar bears look a little green at the zoo?
Odds are, the polar bear has just been rolling around in the grass, they like to do that, but there have been some cases of polar bears turning green because of algae that is able to grow in the hollows of their hair in warmer climates. While it may look strange, the bear is perfectly normal.
So then why is a polar bear's fur transparent? Evolution?
Right you are, it’s evolution. Polar bears evolved from brown bears after thousands of years of natural selection. As the bears spread north, the colder arctic environments favored those with sharper teeth, better cholesterol, and in this case, lighter and “whiter” coats.
Great question, Kylee. Keep the questions coming at niusteam@niu.edu
That’s all for today. Until next time, this has been The Sound of Science on WNIJ Where you learn something new every day.
Where you learn something new every day.
