Say you’re out walking late at night, and you come across a pair of glowing dots in the distance. Maybe they’ll blink at you, or they’ll just watch quietly. Don’t get too spooked – that’s just an animal looking back at you.
It may certainly feel creepy but rest assured that there are no ghostly forces behind those uncanny lights. The reason behind this phenomenon is much simpler: It’s the result of evolutionary mechanisms which allow certain species to see better in the dark.
Why Do Animals Have Eyes That Glow in the Dark?
First, there’s one thing to clarify. When you see these animals at night, their eyes don’t actually “glow,” as in, producing light by themselves. Technically, their eyes are reflecting light from other sources, whether it’s natural starshine or your bright flashlight.
When light passes through our eyes, it hits our retinas, composed of cells called rods or cones. Rods are useful in darker settings, acting as receptors of light. Cones constitute much of our daytime vision, letting us perceive the world in detail and color.
