#funfactfriday Do you know why an animal's eyes shine in the dark? Most vertebrates (and some deep sea aquatic animals) have a specialised layer behind their retina to help them see better in low-light conditions. This layer is called a tapetum lucidum and it acts like a mirror to reflect light that passes through the retina back into the eye. This reflection gives the retina a second chance to detect the small amount of light that is around and thus enhances the animal's ability to see in low-light conditions. All that re-reflected light bouncing off the tapetum lucidum is what gives that 'glow in the dark' shine to an animal's eye.
Extra fun fact: The color of the eyeshine can vary depending on the species and the composition of the tapetum lucidum! Bears generally have yellow to red eyeshine and many cervids (deer, elk) have white eyeshine. Foxes and dogs (like coyotes or pet dogs) often have green eyeshine, but cat eyeshine (both wild and domestic) tends to be yellow to red.
Eyeshine colour is also strongly affected by the angle and amount of light being reflected as well, so sometimes it might look a little bit different.