The Fanged Rogue: The Brazilian Wandering Spider

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The South American ecosystem is known for its variety of dangerous species, from swift and deadly jaguars to large and powerful reptiles like caiman and anacondas. Despite that, it may come as a surprise to find that one of the most dangerous and notorious creatures in this world is a relatively tiny hunter. This small predator, however, possesses aggression comparable to the potential hostility of the large hunters it shares its world with. It wanders through the jungle at night looking for prey, and its weapon is a powerful toxin that can prove deadly to any aggressor, including humans. With its aggression, deadly strike, and reputation as a man killer, it has become one of the more well known venomous species on the planet. This tiny terror is the Brazilian wandering spider.

The Brazilian wandering spider is considered one of the deadliest spiders in the world. © Lennart Pettersson

Eight species of wandering spiders make up the genus of Phoneutria.[1] They can grow up close to 2 inches in length and can reach a leg span of up to 5 inches (females possess larger bodies than males). Like many spiders, one might find their appearance to be somewhat unnerving. A close-up of these creatures reveals a total of eight eyes, two of which are larger than the rest. Their pedipalps (frontal pair of mandible-like appendages) possess a think comb of hairs which differentiates them from similar spiders.[2] They are not tarantulas, despite a somewhat similar appearance. Despite the common name given to these spiders, they are actually found throughout South America as well as Central America.[3]

These spiders are known for the powerful venom and highly aggressive nature.

Most spiders are ambush predators. Many create webs that trap prey, saving the spiders plenty of work when it comes to hunting. Other spiders will create a tunnel or similar lair and ambush any prey that passes by. Most spiders will also remain in these sites for a fair amount of time. Wandering spiders, as their name suggests, travel the jungles at night in search of prey. During daytime hours, these arachnids tend to remain hidden under pieces of wood or behind leaves.[4] Once the dark settles in and the spider feels it can safely venture out in the cover of the dark, it begins its search for prey. Once it comes across a suitable target, it launches itself at the prey and sinks its large fangs into it. The venom is among the most powerful of all spider toxins, and immediately begins to take effect. This venom contains neurotoxins which attack the nervous system and cause the muscles controlling the heart and breathing to shut down. This allows the spider to safely and quickly overpower its prey without fear of the target fighting back. However, that is not all the wandering spider’s venom is capable of. The powerful toxin also contains a high concentration of serotonin which attacks the brain and results in incredible pain.[5] This deadly combination of effects allows the spider to easily subdue its prey. The venom also possesses a rather unusual side effect that results in priapism, a medical condition consisting of long-lasting and painful erections. This unusual effect can result in permanent damage of the reproductive organs. Clearly, being bitten by these arachnids is not a pleasant experience. However, scientists are currently studying the Brazilian wandering spider’s venom as a possible treatment for erectile dysfunction.[6]

Brazilian wandering spiders play an essential role in their ecosystem by keeping the population levels of many insects and other small animals under control. ©Jon Triffo

Unfortunately, encounters with these spiders are rather common. The spiders are known to infest banana plantations and are sometimes carried into cities or towns along with banana shipments by accident.[7] When approached, the spiders will attempt to intimidate their enemy by lifting up its body with the first two pairs of legs lifted high in the air. It will then sway side to side in this position. However, many people do not notice the spider or unexpectedly startle it and receive the painful bite. Although the spider is not to blame, these accidental experiences can result in the death of the bite victim.

A spider in its defensive pose.

Mating can be a risky process if you are a male wandering spider. The female’s larger size and temperament means that the male usually has to make a hasty escape once mating concludes in order to avoid being the large female’s next meal![8] The sperm is stored in a chamber inside the female’s body. It is only in the actual egg laying process that eggs and sperm come into contact and fertilization occurs.

Wandering spiders do not stay in one particular area. They will travel throughout the night in search of prey and usually go into hiding when daytime nears. © Lennart Pettersson

The Brazilian wandering spider may be notorious and aggressive, but these traits may very well be necessary in a world as dangerous as the South American wilderness. Life can be short in this harsh world and, in reality; these spiders simply do what they can in order to survive to the next day. Although tragic incidents may take place when humans and these spiders cross paths, one cannot deny their purpose in the ecosystem as one of the most effective (and possibly frightening) of South America’s predators.

[1] Martins, R. & Bertani, R. The non-Amazonian species of the Brazilian wandering spiders of the genus Phoneutria Perty, 1833 (Araneae: Ctenidae), with the description of a new species ZOOTAXA 1526 pp 1-36 (2007).
Gomez, M.V., Kalapothakis, E., Guatimosim, C., Prado, M.A.M.Phoneutria nigriventer venom: A cocktail of toxins that affect ion channels CELLULAR AND MOLECULAR NEUROBIOLOGY 22(5-6) pp. 579-588 (2002).

[2] “Brazilian wandering spider, (Phoneutria nigriventer, Keyserling 1891) in terrarium.” (2009): 28 Jun 2009.

[3] “Brazilian Wandering Spider.” Available from Internet; accessed 29 April 2011.


[4] “Brazilian wandering spider, (Phoneutria nigriventer, Keyserling 1891) in terrarium.” (2009): 28 Jun 2009.

[5] “Brazilian Wandering Spider.” Available from Internet; accessed 29 April 2011.

6 Hernandez, Vladimir. “Brazilian and US scientists are looking into using spider venom as a possible treatment for male impotence..” (2007): 04 May 2007.

7 “Brazilian Wandering Spider.” Available from Internet; accessed 29 April 2011.


[8] “Brazilian Wandering Spider.” Available from Internet; accessed 29 April 2011.


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On April 29, 2011
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One Response to The Fanged Rogue: The Brazilian Wandering Spider

  1. HCG drops says:

    I savor, cause I found exactly what I was looking for. You’ve ended my four day lengthy hunt!
    God Bless you man. Have a great day. Bye


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