A common question I hear is “why do cats have slits for pupils rather than circles?” And there’s an obvious, yet complicated answer for that. Their eyes are specialized to assist them in being the predator that they are. Being mainly nocturnal, they require eyes made to see in dim light; requiring only 1/6 of the light needed for human vision. The muscles of the iris surrounding the pupil of a cat’s eye are constructed to be narrow slits in bright light and open fully in very dim light, to allow a maximum of illumination. The tapetum lucidum is a layer of tissue located in the back of the eye which acts like a mirror, reflecting light back to the retina. This can increase the light that reaches the retina, which is why their eyes glow when hit by a beam of light, especially noticed in pictures or at night. Big cats appear to have more circular eyes when dilated, because they are nocturnal and see better in little to no light. And let me disprove the rumor that cats are colorblind, although they can’t see directly beneath their nose, they most certainly can see some colors. They’re limited though, not seeing as many colors as we do. Felines do have trouble seeing objects up close, but are keen for visualizing things in the distance. If you catch your domestic cat staring at you and slowly blinking, chances are that’s your cat showing affection..Or plotting your death, you never know.
Photo credit: e_monk