Primary Mouthparts

The first pair of limbs in arachnids are called chelicerae.  Primitively these are pincer-like and composed of 3-segments: basal article, middle article (ending in a fixed digit) and the movable digit.  In some groups the basal article is strongly reduced, modified or lost.  In others, e.g. spiders, most whipscorpions, and many mites, the fixed digit is reduced and the movable digit is fang or stylet-like.