Light is made up by a wide spectrum of colors. The spectrum humans can see goes from red to violet, like a rainbow. Other animals can see other wavelengths, and we know that bees, birds, fish, some reptiles, mice, and bats can see ultraviolet light. Going back to the rainbow, that would be light below the inner purple band where the human eye not perceives nothing.
What we can see differs between species because of our different needs. A bee, for example, can pick up much more of the short wavelengths than humans, and they need this to see colors or patterns on plants that can lead them to nectar. Reindeer also see ultraviolet, and are believed to have developed this ability to discern polar bears and other threats that would otherwise blend in with the white snow.
Our eyes block out the short-wave light to improve visual acuity. It’s a trade-off where we sacrifice this part of the spectrum for higher resolution vision. We can see details better. The downside with that trade is that we see poorly in low-light situations.
Recently, a group of researchers at City University of London compared sights of a large number of mammals and found that hedgehogs, dogs, cats, and ferrets all see a wider spectrum of ultraviolet wavelengths than we do.
Now the question is; when a cat or dog goes crazy over nothing, do they see something we don’t?