We're all fearful of a spider bite, but some are much deadlier than others... Here, we find out what the deadliest spider in the world actually is, why it's so dangerous – and whether we can survive it with a powerful enough dose of antivenom.
What is the deadliest spider in the world?
There are plenty of incredibly dangerous and deadly spiders found around the world, but the most dangerous and deadly for humans is usually judged to be the Sydney funnel-web spider, Atrax robustus.
What do Sydney funnel-web spiders look like?
Sydney funnel-web spiders have a shiny, dark-coloured and chunky body with thick, sturdy legs. Body length can range from 1cm to 5cm, leg length is between 6cm and 7cm, and males and females are a similar size though males have longer legs. They can be black, brown or dark purple-red in colour, and are relatively hairless.
At the front, they have scarily large fangs which are easily strong enough to bite through fabric and shoes and pierce skin. When they bite, they inject venom from large venom glands that causes severe illness and, if left untreated, death.
We named the Sydney funnel-web spider as among the most venomous spiders in the world.
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Where is the Sydney funnel-web found?
The Sydney funnel-web is part of the funnel-web spider family found across Australia, but as the name suggests, this particular species is found in the region of Sydney and eastern Australia. Distribution spans from the Central coast to the Blue Mountains to the Illawarra region.
What are their preferred habitats?
The Sydney funnel-web spider's preferred habitat is damp, moist environments like under logs, rocks, leaves and undergrowth.
Funnel-web spiders are ambush hunters. The family name – funnel-web – refers to its burrow. Individuals create a silk-lined burrow or tunnel in which the spider lives. At the entrance are characteristic radiating threads which act like tripwires. When an unsuspecting insect, lizard or frog walks in front of the funnel and touches a tripwire, the spider will rapidly emerge from its funnel and strike, biting the prey and injecting venom to incapacitate it.
The species tend to be mostly nocturnal, hiding away from higher temperatures and avoiding dry conditions during the day and emerging at night. Heavy rain can lead to more activity, as the water can flood spider burrows.
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What happens if you get bitten by a Sydney funnel-web spider?
Thanks to those immense fangs and the acidity of the venom, the Sydney funnel-web spider has an incredibly painful bite and sometimes won’t let go until physically removed, or shaken off. It will leave clear bite marks from the fangs at the bite site.
As the venom starts to take effect, victims will quickly begin to experience symptoms. This starts with breathing difficulties, which get worse and worse, and pulmonary oedema (liquid on the lungs) can occur. Next comes uncontrolled salivation, with eyes watering profusely, muscle spasms and twitching. If left untreated, this progresses to a massive drop in blood pressure, confusion, unconsciousness, coma, organ failure and finally death. All this can happen in a matter of hours.
This is because the venom contains a neurotoxin called robustoxin or delta atracotoxin which causes a response in the body’s parasympathetic nervous system. Sometimes known as the ‘rest and digest’ system, robustoxin causes a runaway chain reaction that keeps these nerve channels firing until the whole system fails.
Why are Sydney funnel-web spiders so dangerous?
This venom is particularly toxic to humans and other primates. Bites that would produce severe reactions in people can have a much milder and non-lethal effect in pet dogs and cats.
The Sydney funnel-web is also dangerous thanks to those fangs which are strong enough to bite through fabric, pierce a fingernail or break through a shoe.
But really one of the main reasons this spider is so deadly is that humans opted to build a city at ground zero of the geographical distribution of the species. This means humans and spiders share an environment, making the chances of an encounter much more likely.
The male of the species is deadlier than the female (for humans)
The male Sydney funnel-web spider is considerably more dangerous and deadly than the female; the vast majority of cases of fatal spider bites have been attributed to male spiders, and this is for two reasons.
Firstly, researchers have found that the venom of male Sydney funnel-web spiders is 6 or 7 times more potent than that found in female spiders.
Males are also more likely to be found out and about during the summer months as they are looking for a mate, which increases the likelihood of an encounter. In their hunt for a female to mate with, they can make their way into houses and garden. They can even survive a dunk in a swimming pool, thanks to tiny air bubbles trapped in the hair around the legs and body.
Is there an antivenom?
Thankfully, there is an effective anti-venom for the Sydney funnel-web spider. Developed in 1981 by Dr Struan Sutherland at the Commonwealth Serum Laboratories in Australia, it is held by medical facilities and hospitals in Australia and is effective against funnel-web spider bites, including those from the Sydney funnel-web.
This antivenom is created from rabbit plasma which contains antibodies that combat the toxin, created by exposing rabbits to the venom itself.
As an indication of how toxic the venom from the Sydney funnel-web can be, in 2017 a 10-year-old boy required a record-breaking 12 vials of antivenom after being bitten on the finger by a spider hiding in a shoe.
Top image: Sydney funnel-web spider, Atrax robustus, captive female used for milking at Macquarie University, Sydney (credit: Getty Images)
