Funnel-Web spiders come from the family Hexathelidae. There are two genera, Hadronyche and Atrax. Although both genera are dangerous, it is Atrax, which is associated with human fatalities. The Sydney Funnel-Web(Atrax robustos) and the Northern or Tree-Dwelling Funnel-Web(Atrax formidabilis) spiders are the two most venomous of the species and belong to the genus Atrax. Funnel-Web spiders inhabit mostly the east coast of Australia. They can also be found in South Australia, New South Wales, Victoria, Queensland and some of the Southern Pacific Islands. The Sydney Funnel-Web’s habitat is restricted to the Sydney area, as well as adjacent areas to the north and south. The funnel-web spiders and the Australian redback spider are considered to be the two most poisonous spider species in Australia.
Anatomy
Sydney Funnel-Web spiders range in length from twenty-five to thirty-five millimeters in length, are nocturnal and live an average of eight years. The male is smaller than the female and can be distinguished by a small half-spur on its second leg and finely pointed feelers that are used to transfer sperm to the female. Although smaller than the female, male venom is five times more potent, and has accounted for all Funnel-Web related deaths. The shell or carapace of this spider is glossy, with its body being either black or brown. Both sexes are extremely aggressive and rear up on their hind legs, exposing their fangs, ready to strike when threatened. Their fangs are large and powerful and point straight down. The venom they possess is toxic to man and chimpanzees, but isn’t to a wide range of animals, including dogs, cats and rabbits.
Habitat
Funnel-Webs, in general, like moist, cool and sheltered areas. Crevices between rocks, rotting logs and moist earth are the spots they prefer. Funnel-webs need humidity to survive and have been found to make nests around swimming pools, in more populated areas. They build burrows and place silken thread lines on the outside to alert it to danger, a potential mate or its next meal. Most encounters with humans occur, either when the burrows flood or when the male seeks a mate in late summer and autumn. It’s during these times that male Funnel-Webs can be found in garages and homes. Most bites occur during this period.
First aid
Funnel-Web venom contains a neurotoxin called atraxtoxin. This neurotoxin attacks the nerves, causing them to fire repeatedly. After a bite, symptoms include muscle twitching, salivation, tearing and perspiration. It also alters the blood vessels causing shock, coma and cerebral edema. If bitten, the best first aid option would be to immobilize and use a pressure bandage on the bitten limb. The patient would need to be rushed to a hospital to possibly be given Funnel-web antivenom. Although not all bites contain sufficient poison to produce illness, one should still assume that a full dose was given. Envenoming is rapid, so time is of the essence.
Funnel-Web spiders, regardless of type, are highly dangerous and aggressive spiders. They should be avoided, whenever possible. The key to survival, if bitten, is immobilization of the affected limb and speed to the nearest hospital, for treatment.
References
McGhee,K.1999.Funnel-Webs,Australian Geography.53:80-95
