Polar Bear Skin

A polar bear’s fur is made up of two layers – an outer layer, with long ‘guard’ hairs, and a thick undercoat, with shorter hair. The outer layer of hair is clear – and a polar bear’s skin is black.  Polar bears evolved to have black skin, as the color is the best for absorbing energy from the sun.

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This is because objects that appear black don’t reflect any light – and as polar bears are found in countries around the Arctic Circle – Canada, Russia, Alaska in the US, Greenland and Norway – the colder conditions require as much sunlight as possible to be absorbed when it’s available.

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The clear fur allows this sunlight to get to the skin – but it still looks white, so that the bear can blend in with its environment of ice and snow. To learn about this phenomena, we conducted a science experiment with black play dough, straws, and flashlights. Using their fingers, students manipulated black play dough with straws. They then shined their flashlights directly onto the straws. Doing so enabled them to see that even though the play dough was black, the light against it made it look white!

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