Have you ever wondered why cat’s eyes are the way they are? In bright light the pupils of cats look like slits whereas in dim light their pupils look circular. I have documented this phenomenon in the pictures of Science Cat below.
Cats are predators that are biologically designed to hunt at night. The shape of cat’s pupils is an adaptation that reduces the amount of glare during the day and increases the amount of light that enters the eyes during the night. Whereas circular pupils such as those of humans can expand their area 15-fold in going from a fully constricted to a fully dilated shape, those of cats undergo a 135-fold change during this transition. But what allows cats to see better at night is that the density of a type of light receptor in their eyes called “rods” is 6 to 8 times higher than that of a human. Rods permit the detection of very faint light signals. Additionally, cats have a layer of tissue in the back of their retinas called the tapetum lucidum which reflects light back into the light receptors of the eye increasing the amount of light that they can detect. This is why if you use flash photography at night on a cat, like I did with Science Cat below, they look like little demons!
The photographs of Science Cat are property of the author and can only be used with permission.