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Why Do Cat Eyes Glow in the Dark?

If you have ever been a cat owner, then you have likely been surprised walking down the hallway and seeing a pair of glowing eyes. In the past, this characteristic has been a reason for their idolization.

No matter whose eyes we are talking about, from dogs to beavers and humans, all of them reflect light. So, what makes a cat’s eyes different from many other animals? Are there other animals that share this distinctive characteristic? Continue reading to find answers to all your questions and more.

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The History of a Cat’s Glowing Eyes

We have all heard about the idolization of cats in the culture of the ancient Egyptians. They frequently showed up in their writings and artwork, often adorned in jewels and served meals fitting for a king.

There were quite a few reasons that cats were revered in this ancient culture. One of them was their eyes.

The Egyptians believed that a cat managed to capture the sun’s burning, its last glow at dusk, within their eyes. There, cats kept the sun’s rays safe until morning, when they released it back into the sky. They thought cats to be the companions of their favored god, Ra.

In ancient Greek culture, cats were not quite as beloved but were still respected. Greeks thought that cats held a unique power and that the light that came from their eyes was from a gleaming fire behind them.

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Image Credit: Dorrell Tibbs, Unsplash

Why Do Cat’s Eyes Glow in the Dark?

In reality, a cat’s eyes glow because they can reflect light even at night. They can do this because of a particular reflective layer within their eyes called “tapetum lucidum.” The term is Latin for “shining layer.”

The tapetum lucidum essentially acts as a tiny mirror in the backs of a cat’s eyeballs. It allows them to reflect more light and thus see well at night.

How Does This Phenomenon Work?

As light enters a cat’s eye, it acts similarly to how a human’s eye does. Some of the light heads directly to their retina. These cells are at the back of the eyeball and are sensitive to light, containing the photoreceptor cells that allow you and your cat to form a visual image.

However, in cats, some of the other light passes around or through the retina, heading for the tapetum lucidum. It reflects the small amount of visible light at night back through the retina and enhances the photoreceptors’ work.

Finally, what makes their eyes shine is when some of the light bounces back from the tapetum lucidum and entirely misses the retina. This reflection causes the occurrence of “eyeshine,” or the glow in their eyes.

Are Human’s Eyes the Same?

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Image Credit: Angeleses, Pixabay

Humans’ eyes do not have the tapetum lucidum. It is why we cannot see well at night, whereas a cat can safely run around your house when everyone else wants to sleep.

There are plenty of other animals with this extra layer in the backs of their eyeballs. Since it is directly related to night vision, most nocturnal animals have the tapetum lucidum. These include creatures like owls and deer, as well as other non-nocturnal animals, like horses and dogs.

Sometimes, humans confuse the appearance of glowing red eyes in photos of people with the tapetum lucidum. However, the flash on a camera can sometimes be bright enough to cause the redness from a reflection directly off the retina.

If you try to act like a cat and roam around in the dark, you will probably end up being the next thing that goes “bump” in the night.

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Featured Image: 3330852, Pixabay