Major Body Regions

Most arachnids have only two major body regions.  The anterior region (prosoma or cephalothorax) has the mouth parts, legs and eyes and is used for feeding, sensing and locomotion.  The posterior region (opisthosoma  or abdomen) carries out the rest of the body functions.  In spiders and some whipscorpions a narrow waist or pedicel separates the two regions.  In pseudoscorpions, opilionids, and other arachnids the juncture is broad, but unlike in mites, opisthosomal segmentation is clearly present. 

Allow Misinterpretations: Mites have lost a clear distinction between prosoma and opisthosoma, and have two unique body tagmata: gnathosoma (capitulum) and idiosoma (body).  Mites are retained when you use this character if 'Allow Misinterpretations' is checked.