Instinct & Normal Cat Behavior:
How Cats See In The Dark

Can cats see in the dark?

Domestic cats evolved to see in the dark and do much of their hunting at night. Nowadays, that may mean locating the bowl of cat chow in a dark kitchen (and your cat could as easily do that by smell). But in a power failure, while you are still groping for candles, your cat might be strolling through the living room - without crashing into the coffee table.

Cats Seeing in Complete Darkness

Contrary to popular belief, cats cannot see in total darkness, but they can see much better in semidarkness than we, or many other animals, can. This ability is due to the structure of the cat's eye.

Shut up in a windowless, pitch-black room, a cat finds its cautious way by sniffing everything around it and listening carefully. Most importantly, a cat makes use of its two dozen or so long whiskers to get a feel for the room, as they brush against unseen objects in the dark.

Because a cat's eyes are well-suited to dimness, you might guess that in bright sunlight, a cat might find it difficult to see - like a person emerging into sunlight from a dark room with eyes fully dilated.

When our human eyes are behaving normally, the pupils react to bright light by shrinking down to a tiny size. Then, if we also begin to close our eyelids against the glare, we soon cut off all light from entering the shrunk-down pupils.

But cat-eye pupils are vertical slits, which simply get narrower in bright light. Cats have the ability to lower or raise their eyelids to hide more or less of the slit, just like a window shade. This gives a cat more precise control than nearly any other animal over the amount of light entering his eyes.

Scientists estimate that cats can see in the dark clearly in about one-sixth the amount of light we humans would need. How would a scene that is dark to you appear to your cat? To find out, visit the website http://www.lam.mus.ca.us/cats/C10a.

The Cats's Eye

For the size of its head, a cat has extremely large eyes. The eyeball is formed by several layers of tissue. The white part, called the 'sclera, ' is made of tough fibrous tissue rich in blood vessels, which transport oxygen and nutrients to the contents of the eye. The clear outer portion that covers the eye is the 'cornea.' This is made up of extremely thin layers of cells arranged in a unique fashion so the cornea is transparent. The cornea allows light to enter unaffected into the eye.

An animal's retina (the back of the eye) is composed of two major types of light-sensitive cells called 'rods' and 'cones.' Rods are responsible for magnifying light impulses. The cat has an increased number of rods. In humans, 4 out of 5 light-sensitive cells in our retinas are rods, in cats, 25 out of 26 cells are rods.

Cats also have a highly developed reflective area in the back of their eyes called the "tapetum lucidum" (Latin for "bright carpet"). A number of animals, such as deer and raccoons also have this reflective layer. That is what makes their eyes 'glow' at night when our car headlights shine in their faces.

Cat vision is designed for detecting motion, useful for hunting. Like humans, cats have binocular vision, although not as well tuned as in humans. This means a cat most likely sees in 3-D; very useful for judging distance. Cats appear to be slightly nearsighted, which would suggest their vision is tailored more for closer objects, such as prey, that they can capture within running distance. Objects farther than several hundred yards rarely interest a cat.

A cat relies on its extremely sensitive hearing and directional ear movement to locate the general location of prey, then targets and captures the prey using its keen eyesight. Cat vision is adapted to capture even the slightest movement. This makes the cat one of the most successful hunters on land.

Cat Color Perception

Cats seem to respond to the colors purple, blue, green and yellow. Red, orange and brown colors appear to fall outside cats color range and are most likely seen as dark to mid shades of gray. Perceived color saturation appears to be less than that in humans which means they don't see colors as intensely or vibrantly as we do.