With such tiny bodies, it’s easy to forget that most spiders are packed with venom – enough to kill other insects, small animals, and yes… sometimes even humans. Perhaps that’s why spiders are the most feared invertebrates on earth?
While it’s true that most spiders are venomous, what most people don’t realize is that very few of these venomous spider species are actually capable of harming human beings. Still, some spiders can produce enough venom to seriously harm us if we come into contact with them.
But because these species are spread across the globe, it’s hard to know where they are or how dangerous they might be. So let’s take a look at some of the most venomous spiders in the world, so you can avoid any potentially-deadly arachnid encounters on your future travels.
Fringed Ornamental Tarantula (Poecilotheria ornata)
Despite their formidable appearance, Tarantula’s are some of the most harmless creatures in the spider world, and they even make good pets! Most tarantula venom has very low toxicity for humans, and their bites are often likened to a mild bee sting. There are no recorded deaths due to tarantula bites, and in fact, tarantula lovers often say that inflammation from their tiny hairs is the worst you’ll get from these spiders.
Unfortunately, that’s not true for the Fringed Ornamental Tarantula. This 10-inch spider is native to Sri Lanka and is one of the most venomous spiders in the world. Its bite won’t kill (humans, that is) but it will cause extreme pain, muscle spasms, and cramping. Hospitalization is very likely after a bite from this arachnid.
Thankfully the Fringed Ornamental is not an aggressive spider, but they can be defensive and may bite if they feel threatened. They move fast too, so cautious interactions with these tarantulas are always recommended.
Mouse Spider (Missulena)
The mouse spider may sound cute, but it’s far from its harmless mammalian counterpart. There are twenty-one species of the mouse spider, most of which are indigenous to Australia (with one species, the M. tussulena, that can also be found in Chile).
These black, blue, and red arachnids have highly toxic venom, and their bites can cause intense pain. Despite this, mouse spider bites are not significantly dangerous, and more serious effects are rare. Mouse spiders will attack if provoked, but they aren’t especially aggressive.
Interestingly, the venom of the mouse spider has similar levels of toxicity to the infamous Sydney funnel-web spider, another of the most venomous spiders in the world. That is to say, it’s believed that these spiders can be extremely toxic. However, either because of dry bites (bites where no venom is administered) or because they use less venom, their bites are nowhere near as deadly.
Brown Widow (Latrodectus geometricus)
We all know the black widow, but what about its less famous cousin, the brown widow? While it may not be as toxic, it’s still not an arachnid you want to cross paths with. The brown widow is believed to be endemic to either Africa or South America but can be found across various continents and island nations. They thrive in tropical and subtropical climates.
The bite of the brown widow is not severe or lethal, but it can cause unpleasant side effects. As a neurotoxin, it can cause pain and muscle rigidity associated with latrodectism syndrome, caused by the venom of Latrodectus spiders.
Though this spider’s venom is believed to be as toxic as the black widow, it cannot administer the same amount of venom in a single bite, leading to less severe effects. The brown widow will avoid humans and only bites under extreme conditions, so though it is one of the most venomous spiders in the world, bites from these spiders are rare.
Six-Eyed Sand Spider (Sicarius)
You know a spider must be dangerous when its Latin name (Sicarius) translates to ‘assassin!’ These pale brown spiders are found in the southern hemisphere, with some species residing in the deserts of Southern Africa while others can only be found in South America. A member of the Sicariidae family, they are closely related to the brown recluse spider.
The six-eyed sand spider is said to have one of the most lethal spider venoms known to man. Its venom is a powerful cytotoxin, meaning it can cause cell damage or cell death. It is both necrotic, causing premature cell death, and hemolytic, directly destroying red blood cells. This is one spider you don’t want to mess with.
You might be wondering, if its bite is that bad then why isn’t it higher on the list? Well, the six-eyed sand spider lives in extremely inhospitable conditions in harsh desert terrain, so it’s quite rare for a human to encounter them. Its toxic effect on humans has only been recorded twice in the last century.
Chilean Recluse (Loxosceles laeta)
Amongst the famously venomous recluse genus of spiders, the Chilean recluse is said to be the most dangerous of all recluse spiders. It is endemic to South America, though it has been introduced in the US, Canada, and Australia. This spider is especially prolific in Chile.
Though the venom of the Chilean recluse can be highly toxic to humans, its effects vary widely depending on the bite. A small bite may only irritate the skin, whereas a deep bite can cause necrosis (premature cell death) and serious wounds, with 3% of bites in Chile resulting in death. Ice packs and aloe vera gel should be immediately applied to a bite, but a hospital visit is recommended in all cases.
Like the Fringed Ornamental Tarantula, these spiders aren’t aggressive, and they usually hunt at night. But unlike the tarantula, the Chilean Recluse is not a rare species. In Chile, up to 50% of households are said to have Chilean recluse inhabitants.
Redback Spider (Latrodectus hasselti)
Also known as the Australian black widow, the redback spider is another species of spider from the Latrodectus genus, and is found in Australia, New Zealand, and Southeast Asia. It looks very similar to its North American cousin, the black widow, with a red stripe that runs down its back (hence the name).
Also similar to the black widow, the redback is highly venomous, and its bite should be treated with utmost caution. Symptoms of a redback spider bite include the effects of latrodectism (pain, muscle rigidity, vomiting, and sweating), and severe pain for more than 24 hours is not uncommon. More severe cases can result in respiratory failure or death, particularly in young children.
Immediate administration of anti-venom should help patients to recover fully.
Black Widow (Latrodectus mactans)
It wouldn’t be a list of the most venomous spiders in the world without the famous black widow! There are more than thirty different types of these spiders, and they are easily identified by their plump and glossy black bodies and the bright red markings on their abdomens. They are native to North America and are primarily found in the US and Canada, where an estimated 2,500 bites are reported each year.
Bites from a black widow can be very severe, so immediate treatment is recommended. Results can vary from sweating and chills to nausea and difficulty breathing, to seizures and death in severe cases. Before its antivenom was discovered, the black widow bite had a fatality rate of 5% which has now dropped to 1%, and with antivenom, they are extremely unlikely to kill a healthy adult – most black widow deaths occur in elderly adults and young children.
The Brazilian Wandering Spider (Phoneutria)
Also known as banana spiders or armed spiders, the Brazilian wandering spider is a genus of spiders primarily found in South and Central America. They are named such due to their tendency to leave their webs and wander around in the night.
Currently, they are one of the most venomous spiders in the world, with a neurotoxic venom that can cause severe pain, convulsion, and death in some cases. Early symptoms of a bite from these spiders include sweating, goosebumps, and a burning sensation in the affected areas. A powerful anti-venom is available to treat these bites, but affected persons must seek immediate medical care.
Sydney Funnel Web (Atrax Robustus)
At the top of our list is the Sydney funnel-web spider, widely believed to be one of the most dangerous spiders on the planet. The name “funnel-web” comes from the funnel-shaped burrows and webs that these spiders build and live in. They are part of the Atracidae family of spiders and are largely found in eastern Australia.
It is believed that the funnel-web spider has venom that is more toxic to humans than any other spider species, and the side-effects of its bite can include vomiting, muscle spasms, respiratory issues, coma, and death. In almost all cases, severe pain can be expected upon being bitten. A bite from a Sydney funnel-web is considered a medical emergency since the lack of anti-venom can result in death.
Unlike many of the spiders on this list, the funnel-web is quite aggressive, making it a particularly dangerous spider to encounter in the wild. If it feels threatened by a human presence, it is more likely to attack than flee.
What is the most venomous spider in the world?
It is the Sydney funnel-web spider that wins the dubious title of the world’s most venomous spider, with its highly toxic venom that has been described as being twice the strength of cyanide. As a neurotoxin, it can cause intense pain, muscle rigidity, breathing difficulty, convulsions, and unconsciousness. In some cases, it can lead to coma and/or death.
This spider’s venom also contains the compound Delta atracotoxin, which can lead to low blood pressure, circulatory failure, and respiratory failure. The male funnel-web spiders’ bite is six times more venomous than its female counterpart.
Can the most venomous spider kill you?
Yes, a bite from a Sydney funnel-web spider can kill a human in just fifteen minutes, or after as much as three days. This depends on whether the spider is male or female, and how much venom is injected into the bloodstream. These spiders may also latch onto the skin, continuing to bite until removed and injecting venom into the bloodstream several times over.
Though most bites won’t result in death, the only sure way to avoid it is by receiving anti-venom, which is why it is so important to seek immediate medical attention if you’ve been bitten.
What is the largest spider in the world?
The largest spider ever recorded is the Goliath birdeater (Theraphosa blondi), which has an average body mass of 6.2 ounces and hs a body length of five inches. It is part of the Theraphosidae family of tarantulas and is endemic to South America.
Some people consider the giant huntsman spider, found in Laos, to be the largest spider due to its immense leg span, which can grow over 1 foot in length.