Can Cats See Color?

9. Why aren’t cats’ pupils round?

Domestic cats have adapted pupils that look like vertical slits instead of round like humans’ and dogs’. This unusual pupil shape has the ability to open and close rapidly, capable of an impressive 135-to-300-fold change in size in less than a second, much like the aperture of a camera. If you’ve ever watched a cat react to something that has caught their eye, you’ve probably observed this for yourself. Cats’ pupils can range from the size of a splinter to almost completely covering their iris, whereas a human’s eye can only change 15-fold in size maximum. Cats’ pupils are perfectly suited for what they’re designed to do best -- hunting small prey in low light.