The Deadliest Spider in the World

Written by Jeremiah Wright
Published: March 11, 2022
Image Credit Ken Griffiths/Shutterstock.com
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There are more than 43,000 species of spiders worldwide. Of all these species, 30 are known to be venomous and can kill humans, and children are more sensitive to these spiders’ bites than adults. The venomous spider squeezes the venom through its hollow fangs into the victim, enough to cause paralysis. Its hollow fangs work more like a hypodermic needle, injecting substances or extracting fluid.

Spider bites rarely cause human deaths unless left untreated. At least seven people die every year from spider bites, according to the International Journal of Scientific and Technology Research.

Let’s have a look at the world’s deadliest spider.

The Deadliest Spider in the World: The Sydney Funnel-Web Spider

Most Venomous Spider
The Sydney funnel-web spider is considered deadly because its venom kills within a few minutes.

The Sydney funnel-web spider (Atrax robustus) is the most dangerous spider on the planet. This species is native to eastern Australia. The Sydney funnel-web spider is considered deadly because its venom kills within 15 minutes. A male Sydney funnel-web spider also has a more powerful venom than the female; the male is often found roaming alone while the female lives in colonies of around 100 spiders.

At least 40 different species of Sydney funnel-web spiders exist worldwide. Although some of these species are not venomous, their bites should not be ignored because some of them may contain slow-acting venom.

Sydney Funnel-Web Spider: Appearance

Sydney Funnel-Web spiders exhibit color variation, ranging from black to brown, with a shiny thorax and head. Their cephalothorax is covered by an almost hairless, smooth, and glossy carapace. Sydney funnel-web spiders are often mistaken for tarantulas because they strongly resemble them.

Sydney funnel-web spiders have larger venom sacs and fangs. The fangs point straight down without crossing each other. They also have protruding microorganisms at the rear abdominal end. You will notice a mating spur projection between the male’s second pair of legs. Both males and females have velvety hair covering their abdomens.

How Big is the Sydney Funnel-Web Spider?

Their size varies from medium to large. They are about 1 to 5 cm (0.4 to 2 inches) long. Female Sydney funnel-web spiders are larger and better built than males. The females have larger abdomens and shorter legs than the males.

Where Does the Sydney Funnel-Web Spider Live?

Sydney funnel-web spiders live mainly in the moist, forested upland areas. They bury themselves in tree trunks, stumps, or the ground in a funnel-shaped silk web about 60 cm deep. 

Their web entrance is surrounded by many strong strands of silk that normally open into a T or Y shape. These shapes raise curiosity among the unsuspecting prey that easily falls on them.

How Common Are Sydney Funnel-Web Spiders?

Sydney funnel-web spiders are widespread in Australia in that the males are often found wandering in homes and gardens in search of a mate. They also come out of their burrows during wet weather conditions, as they thrive well during such weather conditions.

Since they are usually spotted almost everywhere, the Australian Reptile Park continuously encourages people to collect any Sydney funnel-web spiders they come across and bring them to the park. This is because Sydney funnel-web spiders play a significant role in medicine. Their venom is used to create an antivenom to treat a deadly funnel-web bite. 

What Does the Sydney Funnel-Web Spider Eat?

Sydney Funnel Web Spider
Sydney funnel-web spiders are carnivores whose diet consists of frogs, lizards, snails, cockroaches.

Ken Griffiths/Shutterstock.com

Sydney funnel-web spiders are carnivores whose diet consists of frogs, lizards, snails, cockroaches, millipedes, beetles, and other small mammals. They take all their prey at the edge of their funnel-shaped webs – they ambush the prey, bite it, and drag it inside for consumption.

What’s the reproduction rate of the Sydney Funnel-Web Spider?

Male Sydney funnel-web spiders mature in 2 to 3 years. They then leave the web in search of a suitable mate. A female Sydney funnel-web spider lays over 100 eggs in 35 days after mating. She spends most of her time protecting the eggs during the incubation period. The eggs hatch in about 21 days, and the hatchlings stay with their mother for a few months.

How Aggressive is the Sydney Funnel-Web Spider?

The Sydney funnel-web spider is extremely aggressive. However, it rarely displays this aggression unless it feels threatened. Sydney funnel-web spiders will do their best to defend themselves by raising their front legs off the ground while showing their huge fangs ready to strike. They bite several times if the assailant doesn’t retreat.

How Toxic is the Sydney Funnel-Web Spider’s Venom?

Sydney funnel-web venom is highly toxic. The venom contains many other toxins that are collectively called atracotoxins. The venom can kill humans if left untreated. A male’s venom is considered six times more toxic than a female’s. Nevertheless, all Sydney funnel-web species and genders should be considered potentially dangerous.

What Happens When a Sydney Funnel-Web Spider Bites You?

The atracotoxins and neurotoxins in the venom of a Sydney funnel-web spider will affect the nervous system of a bitten person. When a Sydney funnel-web spider bites you, you will experience the following symptoms:

  • Twitching of the facial muscles
  • Tingling around the tongue and mouth
  • Drooling
  • Nausea
  • Vomiting
  • Excessive sweating
  • Shortness of breath
  • Accumulation of fluid in the lungs and brain in severe cases

These symptoms occur between 10 and 30 minutes after being bitten by a Sydney funnel-web spider. Death happens when too much fluid builds up in the brain, which is called cerebral edema.

How Many Humans Die Each Year From Sydney Funnel-Web Spider Bites?

According to the Australian Museum, Sydney funnel-web spiders bite around 30 people each year. Except for the 13 fatalities documented between 1927 and 1981, there have been no recent deaths from Sydney funnel-web bites. Since then, antivenom derived from the venom of the spider has been created, which successfully treats envenoming within 12 to 24 hours after admission.

Do Sydney Funnel-Web Spiders Have Enemies?

Sydney funnel-web spiders are vulnerable to predators whenever they are out of their burrows. Expert Sydney funnel-web predators are the centipede, blue-tongue lizard, chicken, velvet worms, and flatworms. These predators first immobilize the Sydney funnel-web spiders before eating them.

Other Venomous Spiders

Apart from the Sydney funnel-web spiders, there are also other venomous spiders whose bites require urgent medical attention. Here are the additional top 8 deadliest spiders in the world that you should be cautious of, along with Sydney funnel-web spiders:

1. The Brazilian Wandering Spider

Biggest Spiders: Brazilian Wandering Spider
The Brazilian Wandering Spider is found in South America and Central America.

Tacio Philip Sansonovski/Shutterstock.com

Brazilian wandering spiders are also among the world’s deadliest spiders. They are found in South America and Central America. They are almost as deadly as the Sydney funnel-web spider, but their venom doesn’t kill the victim as fast as the Sydney funnel-web spider.

2. The Chinese Bird Spider

The Chinese bird spider is a deadly spider found in China. Its venom contains neurotoxins that severely affect the victim’s nervous system. Its bite can lead to death if left untreated.

3. The Black Widow Spider

Beautiful example of a False Widow spider. This species is also dangerous to humans but not life threatening as is the case with the Black Widow or Black Button Spider.
A black widow spider’s venom is not highly fatal to humans.

Danie Spreeth Photography/Shutterstock.com

The black widow spider is another dangerous spider found in the United States. Although it is among the most venomous spiders globally, its venom is not highly fatal to humans. However, its bite can be harmful. It’s a good idea to get checked out by a doctor to make sure you aren’t in danger because our immune systems are different.

4. The Indian Ornamental Tarantula

The Indian ornamental tarantula is among the most venomous spiders in south-eastern India. There are no recorded deaths from Indian ornamental tarantula bites, though they are still dangerous. The Indian tarantula’s venom causes intense pain and depending on the immune system, the victims might respond differently to the bites. That’s why seeking medical attention is essential when bitten by this type of spider.

5. Redback Spider

Close up of Redback Spider
The Redback spider’s venom contains neurotoxins that damage the nervous system.

Peter Yeeles/Shutterstock.com

The redback spider is a highly venomous spider that is native to Australia. The female redback spider contains toxic venom, and it’s known to have killed a few people with a single bite. Its venom contains neurotoxins that severely damage the nervous system.

6. Six-Eyed Sand Spider

The six-eyed sand spider is the most venomous spider found in the sandy places and deserts of South Africa. It’s thought to be the most dangerous spider because its venom can cause severe or even fatal wounds.

7. Brown Recluse

The Brown recluse is among the most dangerous spiders native to the United States. Its venom is very toxic but rarely kills humans. However, it’s best to get medical help as soon as possible because the venom always damages cells and tissues.

8. Yellow Sac Spider

Yellow Sac spider (Cheiracanthium) with prey in a pine tree. These dangerous spiders are prolific at night, and have similar venom to the Brown Recluse spider, only a milder dose.
The yellow sac spider is a venomous spider found in the United States.

Brett Hondow/Shutterstock.com

The yellow sac spider is another venomous spider found in the United States. There is not much to worry about if the wound doesn’t get any secondary infections. However, one should get medical attention if the wound develops into a large surface lesion.

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About the Author

I hold seven years of professional experience in the content world, focusing on real estate, nature, and wildlife. Asides from writing, I enjoy surfing the internet and listening to music.

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