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Colour vision in animals

Human eyes respond to light only in the visible region of the electromagnetic spectrum, however, many animals have eyes that respond in different ways. Some animals see no colour. Others are able to detect infra-red or ultraviolet light.

• The red squirrel and the guinea pig have only one type of retinal cell (no cones) and are totally colour-blind.

• Bullfighters often use red capes to infuriate the bull. The bull is probably responding to the movement of the cape not its colour, since there are no cones in the eyes of cattle.

• Cats have very poor colour vision, but under good conditions can distinguish blue-green colors from orange-red ones.

• Many birds and fish have excellent colour vision. The Australian bowerbird decorates its nest with various blue objects such as scraps of paper, juice from blueberries, and feathers from smaller birds.

• Three types of cone cells have been found in hens and pigeons, who have color vision similar to humans. Owls, however, have no cones and are colour blind.

• Many fish are able to distinguish colours. Sticklebacks and Siamese fighting fish react vigorously to red and blue in both courtship and defence of territory.

• Bees are colour-blind to red and orange but are able to see blues into the ultraviolet range, and many flowers are able to reflect that end of the spectrum.

• Ants are unable to see red light. We are able to film their nocturnal activities using red light, which they perceive it as normal darkness.

• Mosquitoes and other unpleasant flying insects don't see yellow so they are not attracted to yellow insect-lights. However they do see purple so bug-zappers emit blue to ultraviolet lights, attracting the insects to a high voltage source which kills them.



 
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© Keith Gibbs 2020