Why do the Eyes of Some Animals Shine in the Dark?

            Have you ever seen a cat sitting in the dark? Though its body may not be visible, its yellow eyes shine in the darkness. The eyes of many other animals like tiger, leopard, and lion also shine in the night, just like the eyes of a cat.

Eyes of cats, tigers, lions, leopards, etc.,shine in the night

            The eyes of these animals have a thin layer of a special crystalline substance, which reflects the light falling on it. This reflected light is the cause of the shine. In the night, even the smallest amount of light falling on this crystalline surface gets reflected and thus eyes who can see things clearly in darkness are called nocturnal animal.

            Studies made on cats have shown that behind the retina of eyes, there is a crystalline layer called the luminous tape turn, which reflects light. Due to this layer, a cat can see clearly in dim light ad its eyes shine in the dark when light is directed on them. Many animals do not have this crystalline layer; hence their eyes do not shine in the dark.

            It has been observed that the color of the shine varies in different animals. It depends upon the number of blood vessels present in their eyes. If the number of blood vessels is large, the color of the sine is red and if the number of blood vessels is less, the color of the shine is white or pale yellow.