A killer is lurking in the suburbs of Sydney, an arachnid with a venom that is powerful enough to kill you in less than an hour. According to Guinness World Records, the title of ‘World’s Most Venomous Spider’ goes to the male Sydney funnel-web. In 2015, after consulting with venom experts, Guinness World Records awarded the record to the Sydney funnel-web. The previous title holder was the Brazilian wandering spider.

The reason for the change was that while the Brazilian wandering spider had been shown to be more deadly in studies on mice, its venom isn’t particularly effective against people. The venom of the Sydney funnel-web, meanwhile, is even more venomous to us than it is mice. The funnel-web’s venom is so deadly that a concentration as low as 0.2 mg for every kilogram of a victim’s bodyweight can be lethal. That means 16 mg (0.00016 g) could be enough to kill an adult human. There is some good news: an effective anti-venom was introduced in 1981 and there has not been a death since.