Brazilian Wandering Spider
The wandering aspect of this aggressive spider can be especially scary, because it's known to scurry from forests to backyards to bedrooms. It's also known to hide in clothes and shoes during the daytime, and has been found in highly populated cities including São Paulo and Rio de Janeiro in Brazil.
In the wild, across Central and South America, this arachnid wanders across the forest floor. It doesn't make a web or stay in one place. It hides in logs and rocks, banana plants and termite mounds.
Although people are often more afraid of spiders than necessary, there's good reason to be afraid of the Brazilian wandering spider -- its bite can be deadly. In fact, it's listed in the Guinness Book of Records as the most venomous animal because of its toxin.
There's a strange impact of the spider's venom when the victim is male: priapism, or a lengthy and painful erection. Brazilian emergency room staffs know immediately the source of a sting when men or boys arrive with intense pain, high blood pressure and an uncomfortable erection.