One of the less offensive but still widespread myths about spiders is that they all have eight eyes. While this is true for many species, and is something that can be used to distinguish a spider from other arthropods, it is not true for all spiders. In fact, spiders can have zero, two, four, six, or eight eyes, and the variety of patterns in eye placement is huge across the Araneae order!
While you’re unlikely to come across spiders with no eyes or two eyes, it may appear that they are common. Most likely, though, you’re finding spiders with four, six, or eight eyes, some of which are very small and hard to see without magnification.
Check out the great websites below for pictures/drawings of the eye patterns of more common spider families:
http://bugguide.net/node/view/84423
http://www.spiders.us/articles/identification/
