Medical Definition of ARTHRODESIS. : the surgical immobilization of a joint so that the bones grow solidly together: artificial ankylosis. the surgical immobilization of a joint so that the bones grow solidly together. ADVERTISEMENT.
Trapdoor spiders are not particularly harmful to man however, like Tarantulas, the tiny hairs on the legs of some species leave tiny red marks where the toothed hairs on the spiders' feet have clung to the skin. Mouse spiders are also a type of Trapdoor spider with huge chelicerae and may measure up to 35mm in body length.
Latrodectus hesperus. The female black widow spider is considered the most venomous spider in North America. The venom of the black widow spider is 15 times as toxic as the venom of the prairie rattlesnake. Only the female black widow is dangerous to humans; males and juveniles are harmless. The female black widow will, on occasion, kill and eat the male after mating. More than 35,000 species of spiders occur worldwide. About 3,400 species of spiders in 64 families are found in North America.