Sharp-Eyed Fish Can Tell Friend From Foe via Facial UV Markings

We know that there's a whole spectrum of different wavelengths of light beyond the puny band of visible light we humans can see. And we knew that some animals, like certain species of fish and birds, have vision that extended beyond ours into wavelengths like ultraviolet. But a new study in Current Biology demonstrates that not only can damselfish see in UV, but that they can discern specific patterns in UV light, which is much more than we ever gave them credit for.