Extremely aggressive (Phoneutria nigriventer )Brazilian wandering spider

Phoneutria nigriventer (Keyserling, 1891), known by the common names of trapdoor or banana spider, is a species of araneomorph spider in the family Ctenidae, considered to be one of the most toxic spider species known. It is a large wandering spider, with an imposing appearance and aggressive behavior, with a size close to that of a human hand, with large reddish chelicerae, two large frontal eyes and two smaller eyes on each side. The legs are thick and furry, making this spider, which is very fast, a feared animal on banana ships, on plantations and in tropical ports. The natural distribution area includes Brazil, Paraguay, Uruguay (where it was introduced) and northern Argentina.

Description

It has large paws, 130 to 150 mm long, with a body size of 17 to 48 mm. The species has a reputation for hiding in bunches of bananas[4], hence the common name banana spider. This behavior, together with its size (it occupies the entire palm of a hand), large chelicerae, authentic fangs, reddish-brown in color, two large frontal eyes and two smaller eyes on each side, to which thick and hairy paws are added, make this spider, which is very fast, much feared on banana ships, on banana plantations, in tropical ports.

Along with the species Phoneutria fera, which only occurs naturally in the jungles between Peru and Brazil, this nomadic spider is considered to be the most venomous of all known spiders.

It follows that Phoneutria nigriventer is the spider species that causes the most accidents, particularly among banana plantation workers. As the species lives in banana plantations, when workers harvest they can be attacked by this aggressive tenant. Its bite is so venomous that the amount of P. nigriventer venom required to kill a 20-gram laboratory mouse is only 6 μg intravenously and 134 μg subcutaneously, compared to 110 μg and 200 μg respectively. for Latrodectus mactans venom.

In addition, its synanthropic behavior, combined with its nomadic ability, allow unexpected places to appear from all over the world, generally associated with bananas and other goods originating in the ports of South America. The presence of the species was reported in early 2014 in the port area of ​​the city of London.

Its venom contains two toxins: the PhTx3 toxin, a powerful neurotoxic agent that blocks muscle control, which leads to asphyxia by paralysis of respiratory movement, and induces intense inflammation of the sensory nerves, producing an extreme pain syndrome; and  the Tx2-6 toxin which triggers strong nerve stimulation and increases the level of nitric acid in the blood producing long and painful bouts of priapism in men.

Some of the side effects of its sting are loss of muscle control, severe pain and difficulty breathing. If the victim is not treated with antivenom, it can cause death due to lack of oxygen. In general, in humans, the poison takes 2 to 12 hours to have its full effect.

As the Tx2-6 toxin contained in the venom of the Phoneutria nigriventer spiders can produce strong erections, lasting up to four hours, by nerve stimulation, Brazilian scientists hope to manufacture from this toxin medicines to help men suffering from erectile dysfunction.