Spiders are among the most feared and misunderstood animals on earth. Spider phobia (arachnophobia) is a real thing for some people, and it is not helped by sensationalist media reporting. Funnel-web Spiders top the list of the most feared spiders in Australia.
There are 35 species of spiders in Australia which are described as ‘funnel-webs’ (subfamily Atracinae). They are found in eastern Australia - including parts of Tasmania and South Australia. Funnel-web Spiders do not occur in Western Australia or the Northern Territory.
The most notorious funnel-web is the Sydney Funnel-web Spider (Atrax robustus) which is considered to be the deadliest spider in the world. From 1927-1980, 14 deaths were reported due to Sydney Funnel-Web Spider bites. No deaths have been reported since the development of antivenom in 1981.
Call Triple Zero (000).
Keep the patient calm and don’t move them unless necessary.
Apply a broad bandage firmly to the bite area and just below it. Bandage firmly up the length of the limb towards the heart and immobilise the limb with a wooden splint.
Ensure airway, breathing and circulation are maintained.
Funnel-web spiders are part of a group of spiders known as mygalomorphs. This group includes other spiders such as Trapdoor Spiders and Mouse Spiders that may be confused with Funnel-web Spiders.
What differentiates mygalomorph spiders from all other spiders is their fangs. Mygalomorph fangs are parallel and are designed for striking downwards and pinning prey down. The fangs of all other spiders point sideways towards each other.
The name ‘funnel-web’ spider is derived from the shape of the web burrow created by the spider. The burrow may be in the ground, under bark in tree stumps or living trees, or under rotting logs depending on the species. Funnel-web Spiders spend their day at the bottom of their webbed burrows and come up to the entrance at night where they wait for prey.
The Sydney Funnel-web Spider (Atrax robustus) is found within a 160km radius of Sydney. Australia’s most populous city is right in the middle of the spider’s territory. This explains why bites from this spider are reported more frequently than bites from most other spiders.
Another significant species of Funnel-web Spiders is the Northern Tree Funnel-web (Hadronyche formidabilis) which occurs from SE Queensland to the Hunter River in NSW. It is the largest Funnel-web – the female has a body length of 50 mm. This spider is also dangerous to humans, and bites may result in severe symptoms similar to those of the Sydney Funnel-web.
Australian Funnel-web Spiders are usually black in colour, and very shiny on the thorax and legs. Their body length varies from about 15 mm to 50 mm depending on the species, with the female being the larger of the genders. For example, the female Sydney Funnel-web Spider has a body length of about 35 mm while the male has a body length of about 25 mm.
Funnel-web burrows usually occur in moist, cool, sheltered areas. You won’t find them in the middle of a sunlit lawn. The most characteristic sign of a Funnel-web Spider's burrow is the easily visible silk trip-lines that radiate out from the burrow entrance of most species – including the tree dwelling ones. The trip-lines are used by the concealed spider to detect passing prey.
The Northern Tree Funnel-web Spider lives, as the name suggest, in trees. Burrows of this spider have been recorded high up in trees about 30 meters above the ground. They and other species of Tree Funnel-webs make silk-lined retreats in holes and rot-crevices in a variety of trees. They usually disguise the burrow entrance with bark or wood particles. Visible trip-lines are usually seen radiating out across the bark of the tree. There also may be more than one entrance.
Trapdoor Spiders, which may be confused with Funnel-web Spiders, are usually dark brown in colour. Some Trapdoor Spiders have lids on their burrows while others have an open burrow. Lid or no lid, the trip-lines of Trapdoor Spider burrows are much less obvious than those of Funnel-web Spiders.
Mouse Spiders are usually brown-black in colour and more compact in shape than Funnel-webs. They dig burrows in the ground but once again don’t have obvious radiating trip-lines like Funnel-webs. Recently, researchers demonstrated that Mouse Spider venom is similar to Funnel-web spider venom. In rare cases where the reaction was severe, Mouse Spider bites have been treated successfully with Funnel-web Spider antivenom.
Male Funnel-web Spiders come out of their burrows in spring to search for females to mate with. This is when they may wander into houses or topple into swimming pools. Male Funnel-web Spiders are considered to be more dangerous than females for two reasons: they are encountered more often, and male venom is more toxic than female venom. Recent research suggests that males evolved powerful venom to protect themselves from vertebrate predators. Researchers described the lethal effects of male Funnel-web Spider venom on humans as an ‘unfortunate evolutionary coincidence’.
After mating, females return to their burrow to lay up to 100 eggs, which hatch after a few weeks. The spiderlings remain in the maternal burrow for a few months during which they moult a couple of times growing larger each time. They then leave the maternal burrow to start burrows of their own. The spiderlings reach sexual maturity after about 5 years. Mature males only survive one mating season, while mature females may live for 20 years.
Funnel-web Spiders can’t swim, but they can survive for hours floating in a pool, or even if they sink to the bottom. They can trap small bubbles of air in hairs around the abdomen, which helps them breathe. Funnel-webs have been known to survive more than 24 hours under water.
Despite their name, the web of a Funnel-web Spider is rarely funnel-shaped and looks more like a long tube or a sock. The visible entrance to a burrow is usually oval with a mesh of trip-lines radiating out from it.
Funnel-web Spider bite symptoms
The bite site may be painful and fang marks are usually seen. Other symptoms include:
How to avoid being bitten