The presence of the tapetum can be observed at night when a pair of glowing eyes reflects back a flashlight or some other light source. (Interestingly, different animals have different color ...

Watch a pond light up with glowing alligator eyes. There's so many of them, and they're bellowing ferociously.

Creatures that sleep during the day and are active at night are known as nocturnal ... The snout, ears, and eyes of these animals can absorb ultraviolet light and project it as blue light.

There are some animals that only come out at night and they are called nocturnal animals. Woo. Woo! Who do you think these eyes belong to? Owls. Owls have big eyes to help them see in the dark.