MOST spiders are totally harmless – but a select few can give you serious trouble if they bite.
Complications from some of Earth's deadliest eight-legged biters include painful erections, vomiting, organ failure, and even death.
BRAZILIAN WANDERING SPIDER
One of the most dangerous spiders to find digging its fangs into your flesh is the Brazilian wandering spider.
They're typically found in northern South America (including Brazil), and can grow to a legspan of around seven inches.
Its official name is Phoneutria, from the Greek "φονεύτρια" – which means "murderess".
This is appropriate given it's one of the few spiders that can actually threaten humans.
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They'll often hide in places where you might end up sticking a body part, like in clothes, shoes, and boxes.
And if you disturb them, they may bite.
The spider has been linked to several deaths, and can kill in hours.
For men, it can also cause a condition called priapism, which is a long-lasting and painful erection.
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Thankfully anti-venoms are available to treat bites, reducing the risk of death.
And here's a fun fact: they're also known as the "banana spider" because some people believe they've been found abroad in shipments of bananas.
BLACK WIDOW SPIDER
Probably the most famous of the deadliest spider lot, the black widow almost needs no introduction.
Officially known as Latrodectus, its species can be found on every continent in the world.
A bite from a black widow can cause significant muscle pain, tummy cramps, sweating, fast heart rate, and spasms.
Many bites don't inject venom, and even envenomated bites don't always result in serious symptoms.
However, there is a very low risk of death for the young, elderly, and anyone with a weakened immune system.
They're notable for having a red hourglass marking on their dark brown or black bodies.
And females are the biggest of the black widows, with legspans coming in at around 1.5 inches.
They rarely bite, and will usually play dead – but can chow sink their fangs into a human if they're trapped, squeezed or pinched.
AVOID BLACK WIDOW BITES
Here's the official advice from the USA's National Capital Poison Center...
Protect yourself in areas where they might live.
- Shake out your gardening gloves before putting them on. Shake out boots or shoes that you've stored in garages, basements, or sheds before putting them on.
- Always wear gloves when moving wood, reaching into wood piles, handling mulch, grabbing empty flower pots, etc.
- If you'll be working in a garage or shed, or under a porch or deck, wear a hat to protect your head.
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If you are bitten, symptoms usually last between three days and a week – but can persist for longer.
SYDNEY FUNNEL-WEB SPIDER
The Sydney funnel-web spider (Atrax robustus) can cause serious illness and even death in humans.
Thankfully it's typically only found in eastern Australia, largely around Sydney.
It delivers a very painful bite, and can even stay attached to you until you try to flick it off.
The spider is defensive, and typically delivers "full envenomation" with a bite, potentially even striking repeatedly.
Symptoms after a bite might include intense nausea and vomiting, muscular twitching, difficulty breathing, confusion, and even unconsciousness.
It's usually considered to be a medical emergency, and requires fast administration of antivenom.
According to the University of Melbourne, death in humans can occur in "as little as 15 minutes".
Thankfully deaths are now very rare due to the development of effective antivenom.
BROWN RECLUSE SPIDER
The brown recluse – or Loxosceles reclusa – is one of the only spiders in North America with dangerous venom.
It often has a violion-shaped marking on its body, giving rise to nicknames like the fiddleback spider or brown fiddler.
The spider is notable for having potent necrotic venoms, meaning they destroy tissue.
This can result in something called loxoscelism where the skin around the bite dies.
And it can also lead to symptoms like nausea, vomiting, and a fever.
It's a reclusive spider so bites are rare – and will typically only strike if pressed against skin.
This can happen if the spider was hiding in a long-unworn item of clothing, bedding, shoes, or gloves.
Very rarely, bites can cause system symptoms that result in blood clots, organ damage, or death.
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But it's typically the very young, elderly, or immune-compromised that are at risk of serious complications.
Wound infections are also rare, but can be treated with antibiotics if diagnosed.