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.
One of the smallest and most venomous spiders in the world is the black widow spider. The venom in a black widow spider is 15 times more deadly than a rattlesnake, but luckily, the spider will only bite in self-defense. One of the largest dangerous spiders in the world is the Northern funnel web spider. It lives in Australia and can grow to be more than 3 inches long. It lives in trees, is attracted to water and can sometimes be found in swimming pools.