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!