Here's how it works:
1. Light enters the eye: When light enters a cat's eye, it first passes through the cornea and lens, just like in human eyes.
2. Light reaches the retina: The light then reaches the retina, which contains light-sensitive cells called rods and cones.
3. Tapetum lucidum reflects light: Instead of the light being absorbed by the retina, the tapetum lucidum, located behind the retina, reflects the light back through the retina again. This increases the amount of light that reaches the rods and cones, making it easier for the cat to see in low light conditions.
4. Increased sensitivity: This reflection allows the cat to see with much less light than humans, making them excellent night hunters.
The tapetum lucidum is made up of crystals that reflect light. In cats, these crystals are usually green, yellow, or blue, which is why their eyes appear to glow in those colors when illuminated in the dark.
So, the next time you see a cat's eyes shining in the dark, you're witnessing the amazing adaptation of the tapetum lucidum, allowing these creatures to see in the dark!