Find out what makes a cat's eyes shine in the dark.
A cat's eyes contain a special light-conserving mechanism called the tapetum lucidum, which reflects any light not absorbed as it passes through the retina of each eye. The retina gets a second chance (so to speak) to receive the light, aiding the cat's vision even more. In dim light, when the pupils of the cat's eyes are opened the widest, this glowing or shining effect occurs when light hits them at certain angles.
The tapetum lucidum, located behind the retina, is a membrane composed of fifteen layers of special glittering cells that all together act as a mirror. The color of the glow is usually greenish or golden, but the eyes of the Siamese cat reflect a luminous ruby red.