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The Sunlight You Don’t See, But Your Cat Does

February 23, 2014

3 Brothers enjoying the blowing leaves of Autumn

Credit: Karen Clarkson
Your rating: None Average: 4 of 5 (18 votes)

Have you ever noticed your cat intently watching nothing?

No matter how hard you look, there is nothing there. Scientists have recently discovered that there may really be something worth your cat’s attention. It’s that cats can see ultraviolet light and you can’t. He’s seeing into the invisible world.

Your cat really is seeing somethingin ultraviolet light. SOURCE: Koshki 13

Most people have seen the science experiment using a prism. When you hold a triangle of glass to sunlight, it breaks the white light into a rainbow of color. It separates the light into different wavelengths of energy. The reds are the longest waves, oranges, yellows are shorter, and so it goes. At the other end of the spectrum are purples and violets, the shortest visible waves.

The waves you see are not the only wavelengths of light. Beyond the reds are infrared waves, which are thermo-radiation, heat waves. When you wear goggles to see infrared, you can trace animals in the dark by their body heat. On the other side of the spectrum are the even shorter waves: ultraviolet (UV). These waves can give you a tan or even sunburn or (with slightly different waves) a useful disinfectant light. Too much exposure to some ultraviolet waves can damage your eyes and cause cataracts.

Sunlight contains not only light we can see but also infrared and ultraviolet which is invisible. SOURCE: American Society for Photobiology

Scientists studying eyes have discovered that a number of animals use ultraviolet to see. Your cat and dog have UV vision, so do rats, mice, moles and bats. The birds and the bees see ultraviolet light, as do all insects, fish as well as some amphibians and reptiles.

Seeing in ultraviolet has some advantages. If you are nocturnal like a cat, and wandering in the dark, seeing more of the light spectrum is useful. Bees see patterns on flowers that help them find pollen. Rodents use it to follow urine trails. Reindeer seem to use UV vision to see polar bears, which, in visible light, blend in with the snow.

A flower in visible light and what a bee sees. SOURCE: Wikipedia

So next time you notice your cat staring intently at something invisible, remember—he may be gazing at rat pee. Aren’t you glad you don’t see it?


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Evelyn Browning Garriss, historical climatologist, is a longtime writer for The Old Farmer's Almanac. She is also editor of The Browning World Climate Bulletin and has advised farmers, businesses, and investors worldwide on upcoming climate events and their economic and social impact for the past 21 years.

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you listed moles as being

By Virginia Robinson

you listed moles as being able to see with ultra violet sight...mold don't have eyes! nothing there, not even sockets ! it is just fur..it's disconcerting really, we recognize where the eyes should be.

See what Jay Gfeller has to

By Evelyn Browning...

See what Jay Gfeller has to say. Thanks Jay!

Many moles do have eyes, they

By Jay Gfeller

Many moles do have eyes, they are just very small and often covered by fur on their snouts.

"Moles have very small eyes that are functional, but in many species they are not discernable [sic] until one pushes aside the fur. Moles also have no external ears (enhancing the smooth, barrel-shaped form of the body). Through field and experimental observations, it's evident that neither sight nor hearing are its primary senses, which isn't terribly surprising for an animal that spends most of its life in the earth in dark tunnels." - Source natureinstitute.org

Thanks for the information,

By Evelyn Browning...

Thanks for the information, Jay!

Like so many animals that live in the dark, moles see a wide spectrum of light, including ultraviolet. Their vision isn't precise, but it uses almost any type of light that reaches their tunnels.

I've always thought it was

By gzuckier

I've always thought it was because their hearing was so much better than ours, they know what's happening in the walls, maybe outside the walls, and that's what they're staring at. Doesn't even have to be mice, just the occasional scratchy insect.

I agree with you. I think

By Evelyn Browning...

I agree with you. I think part of the focus is what they are hearing. But its cool they can also see things that we can't as well.

That cat photo is a little

By georgewilson

That cat photo is a little unnerving--as if cats can see even more than sunlight--maybe spirits?!

I love the picture and it

By Evelyn Browning...

I love the picture and it looks a lot like my cat -- Blossom-raptor. Yes, my bi-polar kitty is unnerving. If any critter could see spirits, it would be her.

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