What is the most poisonous spider in the world?

What is the most poisonous spider in the world? According to experts, the most poisonous spider in the world is an Australian arachnid known as the ” Sydney spider “, although it is also wrongly called the “Sydney tarantula.” This spider is considered the most poisonous in the world and is one of the most dangerous animals in Australia.

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The venom of this spider can cause serious problems, including death, although it is not often that it happens instantaneously, because there is a way to survive, as we will explain in this article of the Expert.

It may also interest you: most poisonous spiders in Brazil

Most dangerous spider in the world

The Sydney spider or Atrax robustus is considered the most dangerous spider in Australia, but also from around the world. She lives in a 160-kilometer radius around Sydney and, according to official records, has killed 15 people in a period of 60 years, specifically between the 1920s and 1980s.

This spider is responsible for more stings than the red-backed spider ( Latrodectus hasselti ) of the black widow family. In addition, it is not only known for the bite, it is also considered the strongest among all spiders and is also one of the most aggressive .

Why is it so dangerous?

This spider is considered the most poisonous in the world because its venom has twice the potency of cyanide . The male is much more dangerous than the female. If we compare, the male is 6 times more toxic than the female or than the younger spiders, which do not yet have venom.

The high toxicity of this spider is due to a toxin called Delta atracotoxin (robustotoxin), a potent neurotoxic polypeptide. The sharp and thin teeth of these spiders can penetrate the nails and even the sole of the shoes. The sting is very painful the acid poison they possess causes great havoc. The marks that the spider bite leaves are very clear and visible.

The Sydney Spider’s Venom attacks the nervous system and affects all organs of the body. Only 0.2 mg per kg of body weight is sufficient to end a person’s life.


Another factor that can be lethal, is the spider keep biting until it separates from the skin. Consequently, the arachnid can inject a large amount of poison, causing serious health problems or even death.

After 10 or 30 minutes of the bite, breathing and the circulatory system begin to malfunction, with muscle spasms, lacrimation or dysfunctions of the digestive tract. A person can die in 60 minutes after the bite if he is not rescued in a timely manner.

Spider-bite – what to do?

The spider bite antidote was discovered in 1981 and since then there have been no more human casualties. As a curiosity, we can mention that it takes 70 extractions of venom to achieve a single dose of antidote.

If the spider bit us at one end, it is very important to make a tourniquet, which we must alleviate every 10 minutes so that we do not stop the blood flow completely, which could lead to the loss of that extremity. If possible, you should try to catch the spider and go to the hospital urgently.

In any case, prevention is much more effective than first aid application. Avoid touching any spider that does not know the species. When camping on vacation, shake the camping tent before entering it.

How to identify the Sydney spider?

The Latin name of this spider reveals her robust constitution . This arachnid is strong and resistant. It belongs to the family Hexathelidae , to which belong more than 30 subspecies of spiders.

Females of this species are considerably larger than males, measuring about 6 to 7 cm, while males are around 5 cm. As for longevity, once again females gain. They can live up to 8 years of age, while males usually live less.

This spider is characterized by having a thorax and a hairless head , of bluish black color . In addition, it has a shiny appearance and has brown abs, in which it has small villi.

It is important to note that the Sydney spider has a similar appearance to other Australian spiders, such as those belonging to the genus Missulena , the common black spider ( Badumna insignis ) or the spiders belonging to the Ctenizidae family .

The Sydney spider produces a painful sting with intense itching . This bite is typical of Mygalomosphae spiders , which have their teeth pointed downwards (like tarantulas) rather than the style of crossed tweezers.

More things about the Sydney spider


The Sydney spider is endemic to Australia and we can find it from the interior of Lithgow to the coast of Sydney. It is also possible to find this spider in New South Wales. It is more common to find this arachnid inside than on the coast, because these animals prefer areas with sand to dig and live.


It is a carnivorous spider that feeds on different types of insects, such as cockroaches, beetles, snails or centipedes. Sometimes it also feeds on frogs and lizards .


Generally, males are more solitary than females. They remain in the same place, forming colonies of more than 100 spiders , while males prefer to have an independent life.

It is a spider of nocturnal habits, since it does not support the heat well. Incidentally, it is important to note that they do not usually come into houses, unless the burrow is flooded or destroyed for some reason. If we do not upset them, the probability of trying to attack them is very low.

Would you like to know the most poisonous spiders in Brazil ? Read our article on this subject.

If you want to read the similar articles in Who is the most poisonous spider in the world? , we recommend you to enter our Curiosities section of the animal world .

Emily Harris

Hi Guys, Girls, and Cats:-p I am Emily Harris, and you can see in above pic. She loves me I swear. I saved her from a dumpster a few weeks back.

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