It looks eerie and even sinister the way some animal’s eyes glow in the dark. When photographed their eyes look like small balls of green or golden fire. Some animals have red or orange tints as well. Many horror stories use this phenomenon to scare us but not many of us know that the shining bright eyes of the animals are a purely biological incident. The animals that have to perform necessary tasks at night, such as hunting, need to see in the dark. This way their chances of survival increases. Dogs and cats have been domesticated but still they are nocturnal hunters and need to see in the dark.
The reason behind the gleaming eyes and their special ability to see is a reflective surface located behind their retinas. This reflective surface is named tapetum lucidum. The job of these special cells are to increase the ability of animals to see better in the dark or in dim light. When light enters our eyes it is received by the photoreceptors located in our eyes. The photoreceptors are responsible to send signals to the brain informing it regarding the light. If the light fails to be received by the photoreceptors then the tapetum lucidum reflects it onto the retina. The retina then is able to perceive the light.
Not all animals have the power to reflect light like this and they can’t see in the dark. Animals such as the kangaroos and squirrels do not have tapetum lucidum. The eyes of animals do not glow in the same color. There is pigments present in the retina that affects the color in which their eyes glow. For example the presence of riboflavin and zinc makes the animal eyes shine in different colors. Nature has endowed all creatures well so that they have a good chance at survival and this is a phenomenon which proves this.