What is the most poisonous spider in the world?

The Brazilian wandering spider is the world's most poisonous spider. Wandering spiders belong to the genus Phoneutria, which consists of eight species. The two most venomous species include P. nigriventer and P. fera.

The neurotoxic venom causes inflammation and intense pain at the bite site, difficulty breathing, priapism and loss of muscle control. High concentrations can cause paralysis and asphyxiation. Anti-venom administration is not always successful.

The wandering spider hides under rocks, logs and termite mounds in daytime. It also hides in bromeliads and banana plants. It wanders the jungle floor at night, and it is seen most often during its April to June mating season.