You may not believe it but Polar bear fur is actually completely see-through, though this doesn’t mean they will be green if they stand on a green lawn. They will appear white because of the way light scatters when reflecting off their transparent fur. Okay we lied, they do sometimes look green! But only because when it gets really too hot, polar bears have been known to stick green algae on themselves to keep cool.
Ask anyone what color a polar bear is and they will probably quickly reply that they are white. However, the truth is that their fur is transparent and has no color at all. They appear to be white to the naked eye because their fur reflects the visible light.
Due to their transparent fur, if you were to try to take a photo of a polar bear in infrared light then they would barely show up at all. Though perhaps the most surprising thing is that their skin color is actually black. To creatures and humans that can only see visible light, polar bears are the perfect predator that is able to blend in almost perfectly into their environment.
However, one mammal has evolved to deal with this situation: deer have a visual system that can outsmart the polar bear’s tricky fur. Deer can actually see in ultraviolet light which allows them to see polar bears extremely easily when they appear on top of an icy white backdrop.
When you see a polar bear at the zoo you may be mistaken for thinking they are yellow or green, but this is due to dirt and age. Or unfortunately, in humid and hot temperatures where polar bears are not native, they sometimes start to see algae growing on their skin. And it can also depend on their diet, for example, when they eat a lot of seals then their fur can start to turn yellow due to the seal’s oil.