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Dogs Can See Colors — But Not Reds & Greens

18 Sep
Dogs can see colors, but not reds and greens. This is due to the number of types of cones in their eyes.

Dogs can see colors, but not reds and greens. This is due to the number of types of cones in their eyes.

It may not be a coincidence that your dog is very good at finding and retrieving the little yellow tennis ball that you throw in your backyard lawn. If that ball were green, or even red, Snoopy might have a more difficult time seeing it (though he could eventually sniff it out.)

The reason is that dogs lack the ability to distinguish between red and green – much like humans who are color blind, according to Meghan Barboza, assistant professor of biology at Southern. And anything with red in it, such as orange or pink, are also off your best buddy’s color chart.

“Something that is red or green would likely appear to be a grayish color to a dog,” Barboza says. “But they can distinguish between light and dark, so they would see some type of difference between a maroon and a light green. But they would see them as light and dark grayish colors.”

In addition, she notes that dogs can’t see orange or purple, either, because red is a part of both of those colors.
And for cat lovers who may be chuckling and thinking this is further evidence that “cats rule and dogs drool”…not so fast. Miss Meowington has a very similar color spectrum to Snoopy.

While Barboza hasn’t conducted her own studies on this subject, she teaches a class on animal physiology and is well-versed on how animals see color.
She explains that the limit on the ability to see colors stems from the number of the types of cones in the eye. Dogs and cats have only two, while humans have three. Horses also have two, but instead of seeing blue and yellow, they see blue and green, but not yellow or red.

But there are animals that have a greater number of cone types in their eyes than people. Toward the high end is the mantis shrimp, which has 16 types of cones. “Experts believe they can see a greater number of shades of colors than we can,” Barboza said. “So, a block that appears as a light green color to us would be seen by a mantis shrimp as a variety of different light green colors. And they may even see colors that we can’t see at all.”

It’s hard to imagine what those colors would look like since human eyes have never seen them.

Barboza notes that birds have a varied number of types of cones, she says. Some have two, others three or four, or perhaps even more.

She says that in general, those animals, as well as insects and other forms of life that have depended upon color to live from an evolutionary standpoint, can see a greater spectrum of colors. Bees, for example, which pollenate colorful flowers, have four types of cones. Their sense of color is probably a bit better than ours. But insects that live underground are believed to have little or no ability to see colors since sight has not been needed for them to continue their existence.

The ability of dogs to see colors has been the subject of much misinformation. Some have said they can’t see colors, while others assume they can see the same colors as us. It’s actually somewhere in between where they can see yellows and blues, but not reds and greens.

So, the next time you plan to paint Snoopy’s doghouse, remember that he’ll only be able to appreciate the aesthetic value if you use yellow or blue paint.

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