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What is the World's Most Poisonous Spider?

Tricia Christensen
Tricia Christensen
Tricia Christensen
Tricia Christensen

There are a lot of rumors and misinformation on the contenders for the world's most poisonous spider. One persistent rumor is that the daddy long legs is the most poisonous spider; but, the rumor goes, that its mouth is too small to bite people. This isn’t true and has been disproved by many scientists. There’s a suggestion that the spider venom secreted from a daddy long legs would probably not make people very ill even if they were injected with it.

A big question in determining the world's most poisonous spider is whether the venom excreted by the spider would actually make humans sick. There are plenty of poisonous spiders that are highly toxic to their normal prey, but wouldn’t do much to the people they bite. If you’re only considering the most poisonous spider to humans, that spider is not, as many think, the black widow. Black widow bites are rarely fatal. Death may occur if the person who is bit is allergic. More commonly, people who are bit by a black widow suffer some pain and illness.

The poison of a Black Widow is potent.
The poison of a Black Widow is potent.

For humans, the two most dangerous spiders are brown recluses and funnel web spiders. Brown recluses are found in a few areas of North America, and funnels webs are located on the Australian continent in fairly defined areas. Both spiders have venom that can cause extreme illness. If small children receive a bite, fatality can result. It should be noted that instant fatality from a spider bite is extremely rare. Compared to the huge number of spider bites from some of the world’s most poisonous spiders, fatalities are extremely minimal.

Many spider bites go unnoticed or cause only minor irritation -- unless a person is allergic to spider venom or the venom is poisonous.
Many spider bites go unnoticed or cause only minor irritation -- unless a person is allergic to spider venom or the venom is poisonous.

Death rates on bites from another competitor for world's most poisonous spider, the Brazilian Wandering Spider, help us get to the truth of the danger of these spiders. Fatal bites occurred in less than 1% of the total number of reported bites. With the funnel web spider, people treated at hospitals for bites tend to require antivenin only about 10% of the time. When many spiders bite they inject little to no venom, though this may vary from bite to bite and spider to spider. In many cases, when people receive poisonous spider bites, they need some medical attention but don’t receive antivenin shots.

Funnel web spiders are among the most dangerous to humans.
Funnel web spiders are among the most dangerous to humans.

Those who receive a spider bite from a potentially dangerous spider should proceed cautiously. It’s better to get medical help, and if possible to bring the offending spider to the treating professional. It can be challenging to identify which spiders are actually poisonous and which ones are merely look-a-likes. It’s better to be safe and receive proper treatment to avoid potentially dangerous or life-threatening complications.

Frequently Asked Questions

What is the world's most poisonous spider?

Bites from poisonous spiders can cause extreme illnesses.
Bites from poisonous spiders can cause extreme illnesses.

The title of the world's most poisonous spider is often attributed to the Brazilian wandering spider, also known as the banana spider. Its venom is highly toxic and can cause serious medical conditions or even death. However, fatalities are rare due to the availability of antivenom and the spider's tendency to deliver dry bites.

How does the venom of the Brazilian wandering spider affect humans?

Individuals who receive a bite from a potentially dangerous spider should proceed with caution.
Individuals who receive a bite from a potentially dangerous spider should proceed with caution.

The venom of the Brazilian wandering spider contains a potent neurotoxin that can lead to severe symptoms in humans, including pain, inflammation, and breathing difficulties. In extreme cases, it can cause loss of muscle control and paralysis, which can be fatal if not treated promptly with antivenom.

Where can you find the Brazilian wandering spider?

Being bitten by a black widow spider typically only causes death in cases where the victim has an allergic reaction.
Being bitten by a black widow spider typically only causes death in cases where the victim has an allergic reaction.

The Brazilian wandering spider is native to tropical South America, with a range extending from Costa Rica to Argentina. They are called 'wandering' because they do not build webs but roam the jungle floor at night in search of prey. They have also been found in shipments of bananas, hence the nickname 'banana spider'.

What should you do if bitten by a Brazilian wandering spider?

If bitten by a Brazilian wandering spider, it's crucial to seek immediate medical attention. While waiting for help, try to remain calm to slow the spread of venom, apply a cold compress to reduce swelling, and keep the affected limb immobilized. Antivenom is the most effective treatment for a serious bite.

Are Brazilian wandering spiders aggressive towards humans?

Brazilian wandering spiders are not typically aggressive towards humans and tend to bite only when threatened or provoked. They may display a defensive posture when they feel endangered, but they prefer to flee rather than attack. Bites to humans are relatively rare and often occur by accidental contact.

How can I avoid encountering the Brazilian wandering spider?

To avoid encountering the Brazilian wandering spider, be cautious in their native habitats, especially at night when they are active. Check shoes, clothing, and bedding before use, and be wary around banana shipments if you're in an area where these spiders may be present. Keeping living spaces clean can also deter them from entering.

Tricia Christensen
Tricia Christensen

Tricia has a Literature degree from Sonoma State University and has been a frequent AllThingsNature contributor for many years. She is especially passionate about reading and writing, although her other interests include medicine, art, film, history, politics, ethics, and religion. Tricia lives in Northern California and is currently working on her first novel.

Learn more...
Tricia Christensen
Tricia Christensen

Tricia has a Literature degree from Sonoma State University and has been a frequent AllThingsNature contributor for many years. She is especially passionate about reading and writing, although her other interests include medicine, art, film, history, politics, ethics, and religion. Tricia lives in Northern California and is currently working on her first novel.

Learn more...

Discussion Comments

anon81199

in biological terms, you're actually looking for the most venomous spider in the world. Poisonous means something that secretes toxins or produces them internally and will kill you if eaten or licked, e.g. certain fish and frogs/toads.

Venomous animals store their toxins and introduce them to the victim by biting or stinging.

anon80848

Just to correct this article a little bit. Spiders are not poisonous -- they are venomous. common mistake easily made by quite a lot of people.

anon22585

Funnel Web Spiders are not kin to Wolf Spiders. Wolf Spiders belong to the suborder Araneomorphae while Funnel Web Spiders belong to the suborder Mygalomorphae. There are vast differences in taxonomy of the two spiders. The wolf spider is more closely related to other Araneomorphs such as Latrodectus Mactans (Black Widow) while the Funnel Web would be more closely related to other Mygalomorphs (though a distinctly different family; the Hexathelids) such as the Theraphosids (tarantulas).

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    • The poison of a Black Widow is potent.
      By: peter_waters
      The poison of a Black Widow is potent.
    • Many spider bites go unnoticed or cause only minor irritation -- unless a person is allergic to spider venom or the venom is poisonous.
      By: schankz
      Many spider bites go unnoticed or cause only minor irritation -- unless a person is allergic to spider venom or the venom is poisonous.
    • Funnel web spiders are among the most dangerous to humans.
      By: Henrik Larsson
      Funnel web spiders are among the most dangerous to humans.
    • Bites from poisonous spiders can cause extreme illnesses.
      By: Creativa
      Bites from poisonous spiders can cause extreme illnesses.
    • Individuals who receive a bite from a potentially dangerous spider should proceed with caution.
      By: ronstik
      Individuals who receive a bite from a potentially dangerous spider should proceed with caution.
    • Being bitten by a black widow spider typically only causes death in cases where the victim has an allergic reaction.
      By: Jürgen Fälchle
      Being bitten by a black widow spider typically only causes death in cases where the victim has an allergic reaction.