Harvestman

Opiliones are known for their exceptionally long legs relative to their body size; however, some species are short-legged. As in the Araneae, the body in the Opiliones has two tagmata, the anterior cephalothorax or prosoma, and the posterior ten-segmented abdomen or opisthosoma. The most obvious 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. Other differences are that Opiliones have no venom glands in their chelicerae and therefore pose absolutely no danger to humans. They also have no silk glands and therefore do not build webs. In some highly derived species the first five abdominal segments are fused into a dorsal shield called the scutum, which in most such species is fused with the carapace. Some such Opiliones only have this shield in the males. In some species the two posterior abdominal segments are reduced. Some of them divided medially on the surface to form two plates beside each other. The second pair of legs are longer than the others and they function as antennae or feelers. In short-legged species this may not be obvious.