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Name: William C
Status: educator
Age: 30s
Location: N/A
Country: N/A
Date: 2001281

Which animals can see in color?

This is far too broad a question since, if I were to use the classical 5 kingdom system, the Kingdom Animalia has millions of species. For examples, many insects see in the UV spectrum, many mammals seem to have similar color vision to our own...but this is very difficult to test, since it is hard to tell what another human is "seeing" when they are color blind to part of the visual spectrum. Can you be more specific?

Peter Faletra Ph.D.
Assistant Director
Science Education
Office of Science
Department of Energy

If you are speaking in the context of birds and mammals, a "general" relationship can be made of those animals that are diurnal (daytime) are mainly possessing color vision while those animals that are nocturnal are often color blind. Many exceptions however, such as owls. If you are speaking in terms of physiology, eyes that have receptor cones see color while those that have rods are know to see better at night; no color. Recent studies have shown some exceptions here as well. Cats may be able to see blues it is thought.

Your question is vague, but I hope I have helped.

Steve Sample

Color is the appearance of a light most affected by wavelength (but wavelength also affects brightness). An animal can see in color if it can discriminate between different wavelengths. Behavioral experiments have demonstrated color vision in many animals and several general trends emerge. Old World primates (great apes, macaque monkeys) have color vision, based upon three different cone types, very similar to most humans. Mammals, that are not primates, have only two cone types and their color vision is dichromatic, e.g. they can discriminate between long and short wavelengths (dogs, cats, horses). One percent of humans are also dichromatic. Birds (pigeon), reptiles (red-eared sliders), fish (goldfish), insects (bee) have color vision based upon at least three cones types. It is likely that most animals see in color.

Physiologically, color vision/wavelength discrimination requires at least two different photopigments. Most vertebrates have rod photoreceptors and at least two cone types. Because rod photoreceptors operate best at low light levels there is no color vision because only one photopigment (rhodopsin) responds. It is often said that cones see color but this is somewhat misleading. Color vision requires that the cones respond but the key is that two different photopigments respond. Reading a book involves cone photoreceptors but the page and words are generally not seen as colors. Neurons which compare the activity of different cone types are color visions foundation and these are called wavelength-opponent neurons.

Michael S. Loop, PhD

Physiological Optics / U. AL at B'ham

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