why do cats eyes glow

Cats' eyes glow in the dark because of a special reflective layer behind their retinas called the tapetum lucidum. This layer acts like a tiny mirror that reflects light back through the retina, increasing the light available to the photoreceptor cells and enhancing their night vision. The light that reflects off the tapetum lucidum and escapes from the eye is what causes the glowing effect known as eyeshine. This adaptation helps cats see better in low light, which is useful since they are most active during dawn and dusk. The glow can appear in different colors (yellow, green, blue) depending on the specific molecules in their tapetum lucidum, such as riboflavin and zinc. The phenomenon is common in many nocturnal animals and is key to their hunting and survival skills in dim light conditions.