According to various sources, including
, the most dangerous spider to humans in the world is the Sydney funnel-web spider (Atrax robustus), which is native to Australia. Its venom is toxic to the nervous system and can cause symptoms such as salivation and irregular heartbeat. The venom potency of this spider is 0.2 mg/kg as a lethal dose for humans. However, an antivenom was developed in 1981, so a bite from this spider likely will not cause death if medical help is available to quickly administer the antivenom. Other dangerous spiders include the Brazilian wandering spider and the black widow spider.
