Sunday, December 18, 2011

The Eye of a Cat: Are Cats Colorblind?

I've often been asked if cats can see color. In truth, this is a difficult question to answer with certainty. Asking a cat is only likely to get you a blank stare. And in all honesty, it doesn't really matter. Cats are hunters, so brightness is more important to their vision than color. They have to be able to see movement and texture. While hunting, color is of little use.

However, an answer to the question of colorblindness and cats can be divined by studying the construction of a cat's eye. The retina is the nerve center at the back of the eye. This retina is composed of cells called cones and rods. Cones are responsible for converting light into color. Rods are responsible for black and white. In the eye of a cat, rods greatly outnumber cones, which is why cats are generally considered to be colorblind.

It's important to note, however, that a cat still has cones. So it is possible, even likely, that a cat can see color. But the number of cones is limited, so your cat probably can't see shades of red. Blues, certainly, and probably greens and yellows.

But your cat doesn't need to see very many colors. Your cat has another advantage. He can see even in the dimmest of lights. Take a look at the eyes of your cat and you'll see why. He can open his eyes wider than you can and his pupil expands to full almost the entire eye, letting as much light in as possible. So hunting in the dark is no trouble for your cat.

In scientific terms, your cat's retinas allow him to see in about one-sixth of the light you need to see clearly. Objects at night appear six times brighter to him than you do to you. And the added rods allow him to detect minute movement, which is only beneficial when hunting.

So, your cat can't see all the colors you can. But he can see some colors and his vision is sharper than yours. It's a trade-off. Less color means more visual acuity. And a cat needs all the visual acuity he can get.

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