The Brazilian wandering spider (a ctenid spider) is a large brown spider similar to North American wolf spiders in appearance, although somewhat larger. It has a highly toxic venom and is regarded (along with the Australian funnel-web spiders) as among the most dangerous spiders in the world. Based on one of the few pharmacological studies performed in the 1970s, Phoneutria’s venom toxicity was more virulent than both Atrax and Latrodectus.
As their name suggests, Brazilian wandering spiders are active ground hunters. If the spider has a reason to be alarmed, it will bite in order to protect itself, but unless startled or provoked, most bites will be without venom. Venom bites will occur if the spider is pressed against something and hurt. In this case, the high levels of serotonin contained in the venom, plus at minimum-strong chelicera, will contribute to deliver a very painful bite.
Children are more sensitive to the venom of wandering spiders. The spiders often make threatening gestures, such as raising up their legs, or hopping sideways on the ground, which might amuse a child to the point of reaching towards the spider. In humans, bites of this spider may also result in prolonged painful penile erections (priapism). Scientists are attempting to create an erectile dysfunction treatment that can be combined with other medicines out of the peptide that causes this reaction.
Most venomous spider according to Guinness.
Guinness World Records has previously named the Brazilian wandering spider the world’s most venomous spider multiple times (though the current record-holder is the Sydney funnel-web spider, Atrax robustus, according to Guinness).
But, as the late Jo-Anne Sewlal, an arachnologist at the University of the West Indies in Trinidad and Tobago, pointed out, “Classifying an animal as deadly is controversial,” as the amount of damage depends on the amount of venom injected.
There are nine species of Brazilian wandering spider, all of which are nocturnal and can be found in Brazil. Some of the species also can be found throughout Central and South America, from Costa Rica to Argentina, according to a 2008 article in the journal American Entomologist(opens in new tab). Study author Richard S. Vetter, a research associate in the department of entomology at the University of California, Agriculture and Natural Resources, wrote that specimens of these powerful arachnids have been mistakenly exported to North America and Europe in banana shipments.
However, Vetter noted, in many cases of cargo infestation, the spider in question is a harmless banana spider (genus Cupiennius) that is misidentified as a Phoneutria. The two types of spiders look similar.