A cat's iris is controlled by tiny muscles in the shape of a figure-eight rather than a circle. In the dark, the muscles pull the iris back like castle gates to allow more light into the eye. In bright light, the gates close and the pupil becomes a narrow slit. A cat's eye can do this in a fraction of a second. An animal with circular muscles controlling its iris can't open its pupils as wide or as quickly, and in the light, its pupils constrict to pinholes rather than slits.
What % Evil Is Your Cat?
5 Minute Quiz 5 Min