How Are Animal Eyes Similar to Human Eyes?

Close-up of dog's eyesPet’s Eyes

When you look into the eyes of your pet, do you sometimes feel like you can tell what they are thinking or feeling? It may seem like a dog’s eyes are very similar to a human’s. And they are! Animal eyes are similar to human eyes in a lot of ways. They use their eyes in the same ways we do – to see their surroundings, blinking and making tears.

Like human eyes, land mammals and fish have eyes that function almost like cameras. Their eyes contain a lens and pupil, just like ours. Their eyes use light-sensing cells that work with the lens, pupil and cornea to take a picture with the eye. That picture is then sent to the brain.

Close-up of cow's eyesEyes Across the Animal Kingdom

In other animals like insects or lobsters, the sight system and the eye’s role in that system are a little different. Lobsters don’t have light sensing cells and rely on the water to reflect light into their eyes. Other insects have less complex systems of sight so that they don’t see the details of the world like we do. They only see what they need to for survival.

Human eyes use a system of rods and cones to help us process color. Some animal eyes have this same system and see colors just like we do. Other nocturnal animals don’t have this same system and utilize light sensing cells so they can see better in the dark. Another group of animals, like fish and monkeys, don’t see the same spectrum of colors that we do. They view the world more like a colorblind human would.

Animal Eyes’ Size & Proportion

Human eyes are a standard size (Eye size or the diameter of the eyeball ranges from 21-27 mm), but Close-up of monkeys eyesacross the animal kingdom, eye size varies widely. Squids have the largest eyes, measuring up to 11 in. in diameter – that’s about the size of a dinner plate! Compare this to the tiny eyes of a bat, a field mouse or even your pet. Squirrels and rattlesnakes have eyes that are an average of just 8 mm in diameter. You may also notice that the eyes of smaller animals are closer in proportion than the size of human eye and head.

Next time you are at the zoo or the pet shop, look around and marvel at the interesting and wonderful variety of eyes in the animal kingdom. You may find they’re more like yours than you expected!

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