There are hundreds more that have not yet been identified. They are all predators and live on plants, in trees, under rocks, on the ground and water. A spider's eyes are on top and near the front of its head. The size, number, and position of the eyes vary among different species. Most species have 8 eyes, arranged in 2 rows of 4 each.
Some spiders have better vision than others.
For example, hunting spiders have good eyesight at short distances. Their eyesight emables them to form images of their prey and mate. Web-building spiders have poor eyesight. Their eyes are used for detecting changes in light. Some species of spiders that live in caves or other dark places have no eyesight at all.