Can Cats See in the Dark?
For thousands of years, cats’ active nature at night was associated with witchcraft and evil. Fortunately, our feline friends have dispelled this myth and become favorite companions in our homes. However, people still question cats’ nocturnal tendencies; it has led individuals to consider whether cats can see in the dark. The simple answer is their vision is good but not quite that good.
How Cats’ Eyes Work
Cats’ eyes function similar to those of humans. The pupil, which is the black center part of the eye, constricts or gets smaller in bright light to reduce the amount of light that enters and dilates or gets larger in darkness to increase the amount of available light that enters the eye. When light enters the eye, it goes to the very back to activate the retina, which is the light-sensitive layer lining the back of the eye.
Cats have a special reflective layer covering the retina called the tapetum, which acts like a mirror.1 It reflects the light to another spot on the retina. If light goes straight into the eye, like when a car’s headlights shine on a cat, the tapetum reflects part of the light right back so that we see the greenish-yellow reflection. (Human eyes do not have a tapetum, so any light reflected back appears red, like the natural color of the retina.) As a result of the light being reflected within the eye, a small amount of light is magnified. This means that any little bit of light at night is enlarged so that the cat can see things. However, cats, like humans, cannot see in total darkness, but they can use up to 50 percent more of the available light than humans can in extremely dark places.2
The Power of Whiskers
Cats have another tool to help them navigate in the dark—their whiskers. Whiskers are connected to nerves that are particularly sensitive to the slightest movement.3 Even a slight breeze can be detected. Cats walk with the whiskers pointing out and forward so when the whiskers brush against an object, the cat will know the object is there.4 This allows the cat to walk through tall grass or a toy-cluttered living room on the darkest of nights without running into objects they can’t even see.
1 Prince, J.H., Diesem, C.D, Eglitis, I., and Ruskell, G.L. (1960): Anatomy and Histology of the Eye and Orbit in Domestic Animals. Charles C Thomas:Springfield, IL.
2 Mead, L.C. (1942): Visual brightness discrimination in the cat as a function of illumination. J. Genet. Psychol 60: 223-257.
3 Fitzgerald, O. (1940): Discharges from the sensory organs of the cat’s vibrissae and the modification of their activity by inon. J. Physiol 98:163-178.
4 Burton, M. (1973): The Sixth Sense of Animals. Taplinger Publishing: New York.
Bonnie Beaver, DVM, DACVB, is graduate of the University of Minnesota College of Veterinary Medicine who lives in College Station, Texas. Dr. Beaver is a professor in the Department of Small Animal Clinical Sciences at Texas A&M University.