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What Is the Brazilian Wandering Spider?

By Karize Uy
Updated Jun 04, 2024
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The Brazilian wandering spider is a genus of spider known to be one of the most venomous animals in the world. As the name implies, this spider is native to Central and South America, specifically in the tropical regions. Its genus name is Phoneutria, a Greek word that means “murderess.” Researchers have recorded eight different species of this wandering spider, the most venomous of which is the Phoneutria nigriventer, the latter word meaning “black belly.” The Brazilian wandering spider is also known as the “armed spider” or “aranhas-armadeiras” in Portuguese.

In 2010, Guinness World Records™ recorded this spider to be the most lethal arachnid in the world, but its deadliness can be easily underestimated due to its small size. Its average size would be 5 inches (around 12.7 cm), with its legs taking up most of its length. Its long legs enable the spider to scurry at a fast speed, with the little hairs across the body helping the spider feel its way around. One of its distinctive physical traits is its prominent fangs that are covered in red bristles. Like many spiders, the wandering spider also has eight eyes, out of which two are bigger.

The Brazilian wandering spider is called such because it is indeed a wanderer. At night, it would usually crawl all over the forest in search of preys such as insects, lizards, and even mice. One can say that this spider is a nomad, as it does not make and live in webs, preferring to actively roam around instead; this is why tropical forests like the Amazon usually do not have spider webs strewn from tree to tree. These spiders are likely to wander so much that they have been seen in banana bunches shipped to the US, garnering them the nickname “banana spiders.” During the day, these spiders usually disappear in dark places such as hollowed logs, termite hills, and even inside the shoes, clothes, and stacks of firewood.

The venom produced by the Brazilian wandering spider is so toxic that only as small amount, 0.00000021 oz. (around .006 mg), is needed to kill an average-sized mouse. The spider bite, aside from being toxic, is also said to be extremely painful, owing to the large fangs of the wandering spider. The venom can cause paralysis and breathing difficulty, which can ultimately result in death. Spider bites can be especially dangerous for men as they can cause priapism, a medical condition wherein the penis experiences a painful and prolonged erection that can lead to impotence. What makes the Brazilian wandering spider more dangerous to humans is that it can be found in highly-populated communities in South America.

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Discussion Comments
By Lodeseba — On Mar 17, 2014

Wow, I don't think I'll ever make fun of a guy for being afraid of spiders again!

I guess they call these "Banana Spiders" for a reason, you can find lots of reports of finding them in the US. Even nests with hundreds of baby ones. Doesn't it make you wonder about all the spiders you normally just ignore?

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