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which colurs dogs and cats can identify. how many types of cone cells do they have in their retina?

Dogs do see in color. However, they see differently than most people do and are less able to distinguish between colors. Veterinary ophthalmologists have determined that dogs see like people who have red/green color blindness. Dogs’ eyes have receptors for blue and green shades, but not for red shades. As a result, it appears that dogs cannot easily distinguish between yellow, green and red, but they can identify different shades of blue, purple and gray. Color is only one of many visual stimuli that dogs detect in their environment. Brightness, contrast, and especially motion, are extremely important to a dog’s interpretation of what it sees.
Many adults think that dogs and cats cannot see any colors, only shades of gray. But this is not true. Cats and dogs can see some colors but not all of them. So in a sense they are like adults who are colorblind. Cats and dogs have cells in their eyes that respond well in bright and dim light. At night, cats and dogs use cells called rods that are sensitive to dim light. They are found in a lining at the back of the eye called the retina. When light falls on the rods, they send a message to the brain to explain the image that they see. For the bright light of day, you need cells called cones. But having cones in your eyes also means that you can also see color. Humans have three kinds of cones that allow them to see blue, red and green. So humans (and monkeys!) can see in full color. Dogs and cats only have two kinds of cones sensitive to blue and green light. So they do see some colors. By the way, if you have a horse or pony at home, they have red and blue cones. Horses see some colors, but they can't tell green from gray.


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