The Venomous Australian Funnel-Web Spiders

Funnel-web Spider

Australia’s Funnel-web Spiders: A Comprehensive Guide to These Fascinating and Dangerous Arachnids

Australia is home to a diverse array of unique and often dangerous wildlife, and among the most notorious are the funnel-web spiders. Belonging to the family Atracidae, these medium to large spiders are endemic to Australia and are renowned for their potent venom, which can cause severe injuries and even death in humans. In this comprehensive guide, we will delve into the fascinating world of Australian funnel-web spiders, exploring their taxonomy, physical characteristics, distribution, venom potency, and the steps to take if bitten.

The Australian funnel-web spider is a highly venomous species found in Eastern Australia, known for its aggressive nature. Its bite can be deadly to humans, but effective antivenom has significantly reduced fatalities.

Taxonomy and Physical Characteristics

The family Atracidae comprises three genera: Atrax, Hadronyche, and Illawarra, with a total of 35 described species. These spiders have robust, glossy bodies ranging in size from 1 to 5 cm in length, with the Northern Tree Funnel-web Spider (Hadronyche formidabilis) being the largest at up to 5 cm. Males are typically more lightly built than females.

One of the most distinctive features of funnel-web spiders is their unique fang structure. Unlike most spiders, whose fangs come together when biting, funnel-web spiders have fangs that point straight down. This allows them to deliver a powerful, stabbing bite when threatened or hunting prey.

Another notable characteristic of some funnel-web species, particularly those in the genus Atrax, is the presence of long, visible spinnerets at the rear of the abdomen. In males, the second pair of legs also bears a large mating spur or spines, which are used during courtship and mating.

Distribution and Habitat

Funnel-web spiders are found along the eastern coast and highlands of Australia, spanning from Tasmania in the south to Queensland in the north. They typically inhabit moist forests and woodlands, although some species can be found in drier, open forests further inland.

Most funnel-web spiders construct burrows in sheltered locations, such as under rocks, logs, and leaf litter. These burrows are lined with irregular trip-lines of silk that radiate outward, acting as an early warning system for the spider. Some tree-dwelling species, like the Southern Tree Funnel-web Spider (Hadronyche cerberea), create retreats in rot holes and crevices high up in rough-barked trees.

Unwanted Guests

Having spiders in the house, especially funnel-webs, can be a worry in Australia. Here’s our tips to help keep these unwanted guests outside.

  1. Seal Entry Points – Check for and seal any cracks in doors, windows, and walls. Use weather stripping around doors and windows to close gaps.
  2. Remove Sheltering Sites – Clear up any clutter around the yard, such as piles of wood, leaves, or debris where spiders can hide. Keep grass trimmed and gardens well maintained.
  3. Use Screens – Ensure that fly screens on windows and vent openings are in good repair to prevent spiders from entering.
  4. Limit Outdoor Lighting – Lights can attract insects, which in turn can attract spiders. Use yellow sodium vapor lights outdoors as these are less attractive to insects.
  5. Regular Cleaning – Keep the inside of your house clean and clutter-free. Vacuum regularly, especially in corners, under furniture, and behind cupboards where spiders may hide.
  6. Check Items Before Bringing Them Inside – Furniture, boxes, and other items that have been stored outside or in sheds should be thoroughly checked before bringing them into the house.
  7. Pest Control – If you live in an area known for funnel-web spiders, consider having regular pest control treatments to manage their population around your property.
  8. Education – Educate your household members about funnel-web spiders, especially identifying them and understanding their behavior, so they can react appropriately and safely.

By being proactive, you can significantly reduce the likelihood of funnel-web spiders entering your home and ensure a safer environment for everyone.

Sydney Funnel-web Spiders

The Sydney Funnel-web Spider (Atrax robustus) is perhaps the most well-known and notorious of the funnel-web spiders. Its range extends from Newcastle to Nowra in New South Wales, primarily in moist forests. However, it is also abundant throughout suburban Sydney, where it favors gardens with dense vegetation and rockeries.

In the Sydney region, two funnel-web species are particularly common: Atrax robustus and the Southern Tree Funnel-web Spider (Hadronyche cerberea). The latter creates retreats lined with bark and wood particles in tree holes, preying on beetles, cockroaches, and small vertebrates.

Venom Potency and Bite Symptoms

Funnel-web spider venom is incredibly potent and contains numerous toxins called atracotoxins, which target the human nervous system. Delta-atracotoxins specifically affect sodium channels, causing uncontrolled neurotransmitter release. This leads to severe neuromuscular symptoms, including intense pain, muscle spasms, twitching, difficulty breathing, confusion, and metabolic disturbances. Without prompt treatment, the venom can rapidly cause hypotension, organ damage, and death.

The venom of the funnel-web spider is highly toxic and is considered more deadly than that of many other spiders and snakes. Its potency is due to the presence of a neurotoxin that can cause rapid onset of severe symptoms, making it more dangerous than the venom of many other creatures. For example, it is faster acting and can be more lethal than the venom of rattlesnakes and many other venomous spiders. However, with the availability of effective antivenom, fatalities are preventable if medical treatment is quickly administered.

Six funnel-web species have been responsible for severe envenomations in humans: the Sydney Funnel-web (Atrax robustus) and five tree-dwelling species of the genus Hadronyche. The venom of male Sydney Funnel-web Spiders is considered the most potent, although bites from females and juveniles can still have serious consequences.

Wandering Males and Bite Risk

The risk of funnel-web spider bites increases during the summer and autumn months when mature males leave their burrows in search of females to mate with. During this time, the wandering males may inadvertently enter houses through cracks and crevices, increasing the likelihood of encounters with humans.

It is important to note that only male funnel-web spider bites have been responsible for human deaths. This is due to the presence of a specific toxin called robustoxin in their venom, which has a severe impact on primate nervous systems. The large human population in Sydney further amplifies the risk of bites from these spiders.

Bite Treatment and Antivenom

If bitten by a funnel-web spider, contact emergency services, remain calm, immobilize the bitten limb, and get to a hospital as quickly as possible. The effectiveness of the antivenom has greatly reduced the threat posed by these spiders, making timely medical intervention the key to a successful recovery.

Symptoms of a Funnel-web Spider Bite

  • Immediate Pain: The bite is often immediately painful, with the pain intensifying over the first hour.
  • Sweating: Localized sweating at the bite site is common.
  • Nausea and Vomiting: Victims may experience nausea, abdominal pain, and vomiting.
  • Neurological Symptoms: These can include twitching, muscle spasms, confusion, and in severe cases, coma.
  • Respiratory Difficulty: In some cases, severe bites can lead to difficulty breathing or even respiratory failure.

Treatment for a Funnel-web Spider Bite

  • First Aid: Apply a pressure immobilization bandage – wrap the area tightly with a bandage, extending up the limb to slow the spread of venom. Keep the affected limb still.
  • Medical Attention: Seek immediate medical help. Funnel-web spider bites require antivenom, which is the only effective treatment to counteract the venom.
  • Antivenom: Since the development of antivenom, there have been no recorded deaths from funnel-web spider bites in Australia. Hospitals stock antivenom, especially in regions where these spiders are prevalent.

If bitten by a funnel-web spider, immediate first aid is key. The bitten limb should be immobilized with a pressure bandage, and the victim should seek urgent medical attention. Prior to the development of an effective antivenom, 13 people lost their lives due to Sydney Funnel-web Spider bites.

Fortunately, a specific antivenom for funnel-web spider bites was introduced in 1981. When administered promptly, it rapidly relieves symptoms, and no deaths have been recorded since its availability. However, it is essential to seek medical care as quickly as possible, even if symptoms appear mild, as life-threatening envenomation can develop swiftly.

Funnel-web spiders, particularly the males, are often perceived as aggressive due to their tendency to stand their ground and present their fangs when threatened. However, these spiders are not usually aggressive by nature and prefer to avoid confrontation with humans.

Behavior and Aggression

  • Defensive, not Aggressive: Funnel-web spiders are defensive creatures. They typically only attack if provoked or threatened, such as when accidentally touched or stepped on.
  • Male Spiders More Active: Male funnel-web spiders are more likely to be encountered and seem more aggressive, especially during mating season when they wander in search of females.
  • Threat Display: When threatened, a funnel-web spider might rear up on its hind legs, displaying its large fangs as a warning.

What to Do If You See One

  • Keep Distance: If you encounter a funnel-web spider, maintain a safe distance. Do not attempt to touch or provoke it.
  • Capture Safely: If it’s necessary to remove a spider from an indoor area, professionals or those with experience should do so using a long object or container to avoid close contact.
  • Pest Control: In areas where funnel-web spiders are common, consider consulting pest control professionals to manage and reduce the presence of these spiders around your home.

Understanding that funnel-web spiders are more inclined to escape than attack can reduce unnecessary fear. Respecting their space and avoiding direct interaction is the best approach to coexisting with these remarkable yet misunderstood creatures.

Funnel-web spiders Facts

Lifecycle: Funnel-web spiders can live for several years. Males tend to live for around 3-4 years, while females can live up to 10 years or more. Females spend most of their life in or around their burrow, whereas males roam in search of mates, especially after rain.

Diet: Their diet primarily consists of insects, small reptiles, and other arthropods. They are ambush predators, waiting for prey to come close to their burrow before striking with speed and precision.

Web Structure: The funnel-web spider’s name comes from the distinctive funnel-shaped web they weave, which serves as both a home and a trap. The entrance to the burrow is often surrounded by trip-lines made of silk that alert the spider to the presence of potential prey or danger.

Venom: Funnel-web spiders have a potent venom that they use to subdue their prey. This venom contains a complex mix of toxins, and while highly effective against insect prey, it can be dangerously toxic to humans and other mammals.

Burrowing Behavior: They are excellent burrowers, with some species creating extensive underground networks that they use for shelter and to ambush prey. The burrows are lined with silk, which helps to maintain a stable microenvironment and to detect vibrations from approaching prey.

Reproduction: Mating can be a dangerous affair for male funnel-webs, as they risk being eaten by females. Males approach females with caution, often plucking strands of silk to signal their presence and intent. After mating, females lay eggs in their burrow, which they guard fiercely until the spiderlings hatch and disperse.

Adaptations: Funnel-web spiders have adapted to a variety of habitats, from dense forests to suburban gardens. Their robust build and powerful fangs allow them to tackle a variety of prey, and their silk webs are marvels of engineering, optimized for detecting and capturing food.

Frequently Asked Questions

How dangerous are funnel-web spiders?
Funnel-web spiders are considered one of the most venomous spiders in the world, and their bites can be fatal to humans without proper treatment. While only a few species, such as the Sydney Funnel-web, have caused human deaths, all funnel-web spider bites should be treated as medical emergencies.

What are the symptoms of a funnel-web spider bite?
Funnel-web spider bites cause immediate pain and local swelling at the bite site. Within minutes, systemic symptoms may develop as the neurotoxic venom takes effect. These can include tingling around the mouth, twitching, sweating, vomiting, confusion, and agitation. As the envenomation progresses, muscle spasms, breathing difficulties, uncontrolled movements, and even coma may occur. Without treatment, the bite can be fatal.

What should I do if I am bitten by a funnel-web spider?
If you suspect you have been bitten by a funnel-web spider, immediately apply a tight pressure bandage to the affected limb and immobilize it. Seek urgent medical assistance, even if symptoms seem mild, as life-threatening envenomation can develop rapidly. If safe to do so, capture the spider for identification purposes.

Where do funnel-web spiders live?
Funnel-web spiders are native to the moist forest regions along Australia’s eastern coast, ranging from Tasmania to Queensland. They can be found in sheltered locations such as under rocks, logs, and leaf litter, and some species inhabit trees. In suburban areas like Sydney, they are abundant in gardens with dense vegetation.

What do funnel-web spiders look like?
Funnel-web spiders have glossy, dark brown to black bodies, typically 1-5 cm in length. They have robust legs and large, downward-facing fangs. Some species have very long spinnerets at the rear of the abdomen. Males can be identified by the presence of a large mating spur on their second pair of legs. The abdomen lacks distinct patterns.

How can I prevent being bitten by a funnel-web spider?
To minimize the risk of funnel-web spider bites, avoid putting your hands in dark crevices and under debris where spiders may be hiding. When gardening, wear gloves and enclosed shoes for protection. Shake out clothing, shoes, and towels left outside before use. Apply insect repellent when spending time outdoors, and always check before grabbing spiders with bare hands.

Are there any treatments for funnel-web spider venom?
Yes, an effective antivenom specifically developed for funnel-web spider bites is available. When administered promptly, it reverses the effects of the venom. However, first aid measures, such as pressure bandages and immobilization, are crucial in buying time until the antivenom can be given.

What is the history of funnel-web spider bites in Australia?
Before the introduction of the funnel-web spider antivenom in 1981, 13 deaths were attributed to bites from the Sydney Funnel-web Spider. Since the antivenom became available, no deaths have been recorded, thanks to improved first aid techniques and the timely administration of the antivenom, which has saved countless lives.

What is the Sydney Funnel-web Spider?
The Sydney Funnel-web Spider (Atrax robustus) is considered the most dangerous of the funnel-web species. Native to the Sydney region, this spider, particularly the male, possesses the most toxic venom, which can be fatal to humans if left untreated.

Australian funnel-web spiders are a fascinating and formidable group of arachnids that command respect and caution. While their potent venom and the risk of severe envenomation make them one of the most dangerous spiders in the world, prompt first aid and the availability of an effective antivenom have significantly reduced the threat they pose to human life. By understanding their biology, behavior, and the steps to take in case of a bite, we can coexist with these remarkable creatures while appreciating their unique place in Australia’s diverse ecosystem.