The Brazilian Wandering Spider is actually the generic name for eight species of spiders that belong to the genus Phoneutria – Greek for “murderess”. It scurries all over the place at night actively searching for prey. It does not wait in ambush or spin a web like other spiders. The notion that damp forests may contain giant webs accumulated over years is a fallacy.
A great many spiders do not bother with webs at all, preferring to be always on the move for the next meal. This species can be identified by scarlet red hairs covering its fangs. Its defensive posture of standing on their back legs, putting its front legs up and swaying from side to side, is also a good identifier. This spider is not afraid of humans and will aggressively attack any that it feels are a threat, making it very dangerous to approach.
Two of the eight species of Brazilian wandering spider are responsible for most bites, and are found in highly populated areas of southeastern Brazil and the Amazon. Most bites occur because the spider wanders at night, then hides during the day in or under anything available – whether that be leaves, plants or logs on the forest floor, or shoes, clothing and boxes in people’s homes.
However, recent studies have shown that these spiders inject no venom in 30% of their bites and only a small amount in another 30%. This means that these same bites can range in effect form mere pinpricks to full-blown poisoning. The Australian funnel-web spider, which is a relative species, apparently injects venom every time, and may therefore be considered more dangerous, though either spider’s venom can lead to a medical emergency.
The Guinness Book World Records of 2007 cited the Brazilian wandering spider as the most poisonous spider and that which is responsible for the most human deaths because of its spider bite. This species is believed to have the most potent neurotoxic venom spider of any living spider. Only 0.006mg (0.00000021oz) is enough to kill a mouse, and not a great deal more is needed to finish off a human.
The Brazilian Wandering Spider is a large brown spider similar to North American Wolf Spiders in appearance. Its bite is at the very least painful, due to the large size of the fangs and the high levels of serotonin contained in the venom. It can be one of the most excruciatingly painful of all spider poisonings. This venom has also been found to cause increased levels of nitric oxide. The effect on male human victims is the same as swallowing Viagra – a long and painful penile erection when it is least required.
While the venom can undoubtedly be deadly, no human deaths from bites have been recorded since the development of an anti-venom in 2004. All the same, any large spider which makes a threat display as obvious as the Brazilian Wandering Spider does when encountered should be treated with caution.
People do occasionally come across similar kinds of spider when unpacking fruit freighted in from overseas, but you are unlikely ever to physically encounter such spiders unless you go off exploring in South America. Even so, it is as well to know what danger they might present if it did happen. These are officially the most dangerous spiders on earth. Be warned.
To read about the nine other most venomous spiders on Earth, follow the link.