How many eyes do spiders have?
Most spiders have eight simple eyes. The two main eyes of a spider each have a simple lens, and a retina which is made up of light sensitive cells whose surfaces point toward he light as it enters the eye. These main eyes have a small field of vision with high resolution. They are especially well developed in jumping spiders. A spider’s secondary eyes also have a lens but the light sensitive cells of these eyes point away from the light as do the similar cells in a human eye. The secondary eyes detect shadows and the difference between light and dark. A few spider families are characterized by only six eyes.
