Harvest-spiders

The Opiliones are known for having exceptionally long legs relative to their body size. As in all Arachnida, the body in the Opiliones has two tagmata, the anterior cephalothorax or prosoma, and the posterior 10-segmented abdomen or opisthosoma. The most easily discernible difference between harvestmen and spiders is that in harvestmen, the connection between the cephalothorax and abdomen is broad, so that the body appears to be a single oval structure. The stomotheca is formed by extensions of the coxae of the pedipalps and the first pair of legs. Most Opiliones, except for Cyphophthalmi, have a single pair of eyes in the middle of the head, oriented sideways. Harvestmen have a pair of prosomatic defensive scent glands (ozopores) that secrete a peculiar-smelling fluid when disturbed. The legs continue to twitch after they are detached because 'pacemakers' are located in the ends of the first long segment (femur) of their legs. Typical body length does not exceed 0.28 in, and some species are smaller than 1 mm, although the largest known species, Trogulus torosus (Trogulidae), grows as long as 0.87 in.