The Function of a Cat's Eyes

Cats' eyes are amazing and different from human eyes in a number of ways. Not only can they see well in the dark, but they are made to track quick movements. They come in a in a dazzling array of colors and seem to peer deep into you. Have you ever wondered exactly how cat's eyes work? Here's a breakdown of a cat's vision and how important their eyes are to them.

Shape and Size of a Cat's Eye

The lens of a cat's eye is larger then humans. A larger lens means it's more difficult for a cat to focus on objects close to them. The pupil of the eye is also larger a humans pupil. As a nocturnal hunter, a cat's pupil needs to open and constrict very quickly. Their pupils are oval or vertical shaped, unlike a humans round shaped. The oval shape is important for hunting at night as it helps gather in light.

Night Vision and a Cat's Eye

Cats are excellent night hunters because their eyes are made to see in dimmer light. While they still need some light to see, their night vision is much better then humans. In a cat's retina, there is more rods then cones. Rods are important for night vision and tracking quick movements. More cones, like in a human eye, are good for seeing color and operating in the daylight. Cat's eyes also have tapetum lucidum behind the retina. The tapetum lucidum is up to 15 mirror-like cells. This is how cats' eyes reflect and seem to glow when light hits them in the dark.

Cats' Eyes and Color

It is a myth that cats only see white and black. Since a cat's eye does have cones, it can see a small variety of colors. Cats are color blind in the way some humans are. They can see blues and purples, but have trouble with reds and greens. Since cats can not see color as well as humans can, they have less distractions when concentrating on hunting. Color vision is not important to cats, since it is the movement of the prey that needs to be focused on. It is also a myth that all white cats with blue eyes are deaf. They do have a higher rate of genetic deafness, but it does not affect every blue eyed white cat.

The Cat's Third Eye

Cats have a third eyelid that is sometimes referred to as a "third eye." Named the nictitating membrane, it helps keep a cat's eye moist and protect its vision. This membrane is useful in hunting, as the cat does not need to blink as frequently as humans do. Cat owners can see the membrane when their cats get sleepy or sick.

While cat's eyes are similar to a humans, they are different in many ways. Cats as night hunters use all of the parts of their eyes in order to catch their prey. The next time you peer into your cat's eyes, think about how they see the world.

Sources:

http://www.cathealth.com/CatEyes.htm

http://www.agarman.dial.pipex.com/bco/fact4.htm