The Brazilian wandering spider, also known as Phoneutria fera and Phoneutria nigriventer, is considered the most venomous spider in the world
. Its venom is toxic to the nervous system and can cause symptoms such as salivation and irregular heartbeat. Hundreds of bites are reported annually, but a powerful antivenom prevents deaths in most cases. The Sydney funnel-web spider, Atrax robustus, is also one of the most dangerous spiders to humans in the world, with a venom potency of 0.2 mg/kg as a lethal dose for humans
. However, anti-venom was developed in 1981, so a bite from this spider likely will not cause death if medical help is available to quickly
