Ask anyone what colour a polar bear is and they will exclaim, “white” with great enthusiasm, but truth be told, their fur is actually transparent and holds no colour. It only appears white because it reflects visible light. They’re nearly invisible under infrared photography. Polar bear skin, surprisingly however, is black! To humans and other creatures that see only in visible light, polar bears nearly blend in seamlessly with their environment. However, reindeer have outsmarted the polar bear’s tricky fur by evolving a visual system that can see in ultraviolet light, which means polar bears stand out like a sore thumb against their icy white backdrop.