Learning to Live with a Killer
The deadly funnelweb spider is one resident of Sydney that officials hope will shun the Olympic Games
- Karen McGhee - Photographs by Esther Beaton
- Sep 01, 2000
Working his way along a gentle slope leading down to a creek bed, Nathan Kirkwood lifts large rocks and clumps of casuarina leaves, searching for burrow entrances with silk trip lines radiating outward.
"Funnelwebs tend to excavate in softer ground and along natural cracks and crevices," he says. "Basically, we´re after depressions containing moisture or places where the water table is close to the surfacemoist spots with rocks or leaf litter providing plenty of cover."
We are in the southern outskirts of Sydney, and the burrows Kirkwood is trying to find belong to one of the world´s most dangerous spiders - the Sydney funnelweb (Atrax robustus). I´ve lived in this city for six years and I´ve never seen a funnelweb in its natural habitat. In fact, I´ve intentionally avoided settling in the suburbs favored by the species. The prospect of this encounter makes me more than a little anxious, and I jump with each glance of a grass blade or tree branch against my skin.
Kirkwood, an amateur spider enthusiast, politely avoids commenting on my arachnophobia. He´s been fascinated with these creatures since childhood and now shares his bedroom with six of them in a large terrarium. As he continues lifting rocks and leaves, Kirkwood notes that "funnelweb" is a bit of a misnomer.
"Their webs aren´t really funnels, more like long flattened purses," he says. The web has a slitlike aperture at the burrow´s entrance where the spider sits, well hidden, and waits to ambush hapless insects, small lizards or even frogs that set the trip lines vibrating.
I´m not normally bothered by spiders, but the Sydney funnelweb has an intimidating reputation. It´s big and aggressive, with a bite that´s been known to kill a child within 15 minutes. It is responsible for the deaths of 13 people between 1927 and 1981, when an antivenin was released. Despite my fears, I have a certain morbid fascination with funnelwebs. I´m eager to know more about them, and to discover how people have learned to coexist and even benefit from their relationship with this deadly arachnid.
The Sydney spider is one of about 40 funnelweb species in eastern and southern Australia. The other species are also venomous, but because they live in isolated locations, they are rarely encountered by humans. Sydney, Australia´s largest city and site of this year´s Olympic Games (see box, page 40), is located in the center of Atrax robustus´ range.
Despite the danger, many Sydneysiders aren´t bothered by these spiders. Take, for example, Gwen David and her family, who moved here from Melbourne about 30 years ago. Ignoring the advice of friends, they settled in the notorious funnelweb suburb of Seaforth and have since managed to live there without mishap by taking a few simple precautions.
"Always wear shoes outside, particularly at night," Gwen David says. "Always wear gloves when gardening and be careful when you lift up logs or old bricks."
When the family began building their Seaforth home, the excavations disturbed hordes of funnelwebs. Long after the house was completed, the spiders regularly turned up in bedrooms and bathrooms. "You just learn to live with them," Karen Burgess, David´s daughter, says nonchalantly.
Burgess was rarely troubled about growing up among funnelwebs. Now, having moved only a few suburbs away from the family home, she is teaching her own children about the simple routines needed to avoid bites. "You always check for spiders in shoes or clothing left on the floor," Burgess says. "And you never thrust your hands into the swimmingpool filter to clear out leaves without first checking for funnelwebs!"
While Burgess´ easygoing attitude toward funnelwebs is representative of most Sydneysiders these days, the city wasn´t always so relaxed about its infamous spider. It wasn´t until the early 1980s, when a team led by Melbourne based medical researcher Struan Sutherland developed the first successful funnelweb antivenin, that life with these spiders became much less worrisome.
The antivenin, which has saved dozens of lives in the past two decades, is made possible in large part by the tireless work of spider experts at the Australian Reptile Park in Somersby, north of Sydney. Chief among those experts is Lyn Abra, who milked funnelwebs for their venom for three decades, first for Sutherland´s research and then for commercial antivenin production. Although recently retired, Abra remains well respected for her knowledge of Australian spiders.
While at the reptile park Abra established and maintained a colony of hundreds of funnelwebs in glass jars and terrariums, and I went to her to get my first closeup look at one of these spiders. Nicknamed "the funnelweb lady," Abra turned out to be not a Morticia Adams, but a gracious grandmother. The specimen she showed me was truly magnificent. From the tip of the female spider´s head to the spinnerets at the end of her glistening black abdomen, she measured about an inch and a half. Her long legs, covered with short sensory hairs, made her appear even larger. Abra nudged her gently with a glass pipette and the spider reared up into the classic funnelweb defense pose: head back, front legs raised and fangs on display. After a little more stimulation, two large drops of venom glistened on the end of her huge fangs. Then she quickly snapped her head forward and down repeatedly with a force intended to propel the fangs through the exoskeletons of prey such as millipedes and cockroaches.
Funnelweb attacks are so forceful that one bite victim reportedly turned up at a hospital with the spider´s fangs still embedded in his toenail. That tale may be true, but there are many other fictional funnelweb horror stories that often circulate in Sydney.
"There are two main fallacies," Abra told me. "They don´t jump. And they don´t chase after people." Also contrary to urban mythology, funnelwebs don´t roam around the house making "gnashing noises" with those enormous fangs.
The male of the species does roam, however. The female, which is thought to live more than 12 years, inhabits a burrow from which she rarely strays more than a yard. Males leave their burrows at maturity, probably between two and three years of age, to search for mates. Abra believes a combination of warm temperatures and high humidityconditions most often encountered during Sydney´s spring and summer trigger the sexually mature male funnelweb´s urge to roam.
He is thought not to eat during his reproductive sojourn and, as a result, dies between 6 and 12 months later. In most spiders, it´s the female of the species that has the more dangerous venom. But, in funnelwebs, the venom of the wandering male is far more potent. Males are responsible for most bites, and probably all deaths, in humans. No one knows why the roaming male needs such potent venom, particularly when he is presumed not to eat, but perhaps the venom is for defense. In their burrows, funnelwebs face aggressive predators such as centipedes and king crickets. When they´re on the move, they´re also susceptible to attack from reptiles, birds and small marsupials.
All of the worst encounters between humans and funnelwebs involve male spiders looking for mates. Usually the victims are residents of suburbia doing ordinary things. Such was the case on January 1, 1998, when Trevor Ryan, then 12 years old, was bitten on the foot. Ryan had lifted a board in the backyard of his home to clear the lawn for a game of cricket. The male funnelweb beneath had probably stopped there for shelter after a night of searching for females.
Ryan recalls that the pain from the bite was so excruciating he was convinced he was going to die. Less than two decades earlier, a similar bite certainly would have been fatal. But after treatment with antivenin and a short stay in the hospital, Ryan recovered with no ill effects.
What makes the funnelweb´s bite so painful are the size of the fangs and the acidic nature of the venom, according to Graham Nicholson of the University of Technology, Sydney. Nicholson is one of several researchers in Australia investigating funnelweb venom, most of whom are hoping to find commercial applications for the compounds it contains. Nicholson is particularly interested in potential biomedical uses. But he is also collaborating on a project headed by Glenn King, a former University of Sydney professor who now works at the University of Connecticut.
King´s team is investigating chemicals within the funnelweb´s poisonous cocktail that target insects. These may provide the basis for new, environmentally friendly pesticides. Tests on one toxin indicate that it kills insects quickly but has no impact on the cells of humans or other mammals.
Only one of the 50 or so different compounds in funnelweb venom affects humans. This substance, known as deltaatracotoxin, is a neurotoxin that targets the nerves leading to muscles, making the muscles twitch uncontrollably. "It looks like you are shivering," says Nicholson. "You can´t breathe properly and you get respiratory collapse. That, combined with some cardiovascular effects, is usually what kills you."
This overstimulation of the peripheral nervous system also affects the glands, so that victims produce profuse amounts of sweat, saliva, tears and fluid in the lungs. Strangely, the only mammals this neurotoxin is known to affect are primates, which lack a substance in their blood that inactivates the venom. No one knows why primates are missing this protective substance. Experts regard it simply as a quirk of nature.
Funnelwebs appeared on Earth long before humans, evolving more than 50 million years ago, when Australia was covered in warm, humid forests. As a result, modernday funnelwebs suffer readily from desiccation and dehydration and tend to prefer moist, leafy environments. That explains why Kirkwood has so much trouble finding these spiders when we go looking for them.
It is very hot and dry, as it has been most of this summer. Kirkwood sees lots of evidence of previous funnelweb occupation but, he speculates, most of the spiders have left for moister surroundings, have died from dehydration or have dug down closer to the water table.
Just as we are about to give up, Kirkwood finds fresh silk. He explains that the long webs that extend down into the burrows give the spiders a surface across which they can maneuver more easily than dirt. The webs also provide insulation and strengthen the burrow´s walls. Excited, Kirkwood digs down about a foot, exposing a large main burrow with several side chambers containing juveniles. Eventually, he reaches the mother. Upset by the disturbance, she rears back and starts striking blindly, repeatedly raising her fangs and snapping them down like a crazed windup toy.
It is, at first, a fearsome display. But she tires quickly, apparently suffering from exhaustion and dehydration. We gently trickle water around her and Kirkwood restores her burrow. As she disappears, it becomes clear to me that the seeming ferocity of these spiders masks an underlying vulnerability. And so, with that brief encounter, my anxiety about funnelwebs starts to abate.
I ask Kirkwood about the prognosis for the mother we´ve disturbed. "Funnelwebs are survivors," he says. "This one must´ve been living here for years and I reckon she´ll do alright here, for a while yet."
Athletes and Arachnids
Thousands of athletes and spectators from around the world are expected to descend on Sydney this fall for the Olympic Games. Will the presence of a deadly spider pose a threat to these visitors?
"We´ve had no reports of funnelwebs on Olympic sites at all," says Sandie Watson, a spokesperson for the Olympics. "So we´re not expecting any problems."
Brad Harvey, a spider expert with the Australian Reptile Park, confirms that funnelwebs are not a problem in western Sydney, site of most Olympic venues. But it could be a different story in other parts of the city.
"If we have high rainfall, we could have a lot of male funnelwebs out and about," warns Harvey. "But it´s important that visitors realize we have a successful antivenin in Australia and, because of that, we haven´t had anyone die from a funnelweb bite in 20 years." K.M.
Australian journalist Karen McGhee writes frequently about natural history.
Esther Beaton photographed and wrote the story on malleefowl in the July/August 1999 issue.