Why Do Animals Have Eyes that Glow In The Dark?

Everyone has taken a walk at night and noticed eyes glowing in the dark – watching their every move.  So why do some animals have eyes that glow?

Animals, especially ones who are active at night, have a reflective surface behind their retinas.  That surface is called a tapetum lucidum and it will help them see in the dark.  Basically its job is to reflect light, like a mirror, in the eye to allow what little light there is at night to hit photoreceptors in the eye.

Many animals have a tapetum, including horses, cows, deer, dogs, cats and even ferrets. The color is generally green to yellow, but it is affected by substances, like zinc, in the tapetum.  A pet’s tapetum can also change color as they age.

So next time you take a walk at night and see eyes watching you, appreciate the beauty of that animal’s tapetum!

Comments

  1. why does my 2yr old german sheperds eyes reflect green in a photographs

    • Nicole Becker, CVT, Practice Manager says:

      That is a great question!
      Dogs, and most animals, have a reflective layer behind the retina of the eye called the tapetum. This is normal anatomy for a dog, which enhances their ability to see at night. Light is reflected outward, allowing the dog’s retina another chance to absorb the rays. Any of that light that is NOT absorbed, then exits the eye, appearing green in photographs. This also is why their eyes seem to glow in headlights and flashlights. Some dogs may lack pigmentation in the tapetum, in this case their eyes would shine “red” like a human.

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