Why do cats eyes only see black, white and grey?

Answer 1

Animals that see only in gray-scale have rod cells only in the receptors of their retinas. Cone cells are required for color vision.

Answer 2

Do they? I thought they had two types of color receptors.

The spectrum of colors an animal can see is determined by the number of different types of color light receptors they have in their eyes and the wavelengths of light they respond to. Humans have 3 types of color receptors and dogs have 2. I thought cats had 2 too, but I could be wrong. If they only have one, then they would have monochromatic vision, eg grayscale.

Answer 3

In cats, blue and green appear to be the strongest colors perceived and they also seem to respond to the colors within the purple, green and yellow range. Red, orange and brown colors appear to fall outside cats color range and are most likely seen as shades of gray or purple so thay can see in color but it is limited compared to human eyes.

Answer 4

MadSci Network: Zoology Query:


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Re: Are cats color blind?
Date: Fri Aug 14 14:03:08 1998
Posted By: Lynn Bry, MadSci Admin
Area of science: Zoology
ID: 900690999.Zo
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Message:

Howdy -

Cats are not color blind - they have the ability to distinguish between blues and greens, but lack the ability to pick out shades of red. The Natural History Museum of L.A. has online images demonstrating how cats view the world.

Cats, like humans, have two primary structures in the retina of the eye for perceiving light: rods which help us see light and dark areas, and cones which have pigments to detect particular wavelengths of light. At low light intensities, rods function to distinguish light from dark. You may notice that you see little color in dim light. At high intensities of light the rods do not function, however, the cones do. Humans have three kinds of cone pigments, ones that can detect red, green and blue light. It's no coincidence that we find these same colors in the screen of an average color-TV set. The ability of an organism to see in "color" thus depends upon the color receptors present in the retina. People (or animals) lacking a specific color receptor are unable to "see" that color. Most often, it appears greyish, or as one of the other colors that can be detected (i.e. purples appearing greyish-blue). Green color-blindness is the most common genetic form of color-blindness in humans, followed by red, then blue.

The Talk Origins website has a good discussion on the nature of color vision and what it means to "see" in color.

-L. Bry, MadSci Admin

References:
Yokoyama S. Radlwimmer FB., The "five-sites" rule and the evolution of red and green color vision in mammals. Molecular Biology & Evolution. 15(5):560- 7, 1998

Loop MS. Bruce LL. Cat color vision: the effect of stimulus size. Science. 199(4334):1221-2, 1978



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Answer 5

That's all they need for hunting at night. Smell and hearing are heightened to compensate.