There is one species of spider.
Latrodectus . The genus contains 31 recognized species distributed worldwide , including the North American black widows ( L. mactans , L. hesperus , and L. variolus ) , the button spiders of Africa , and the Australian redback spider . Spider . They are the largest order of arachnids and rank seventh in total species diversity among all other orders of organisms . A minority of species are social , building communal webs that may house anywhere from a few to 50,000 individuals . Social behavior ranges from precarious toleration , as in the widow spiders , to co-operative hunting and food-sharing .