AUSTRALIAN INVERTEBRATES
FUNNEL-WEB SPIDERs
They are a group of Australian spiders belonging to the family Atracidae. They include some of the most venomous spiders on the planet and are generally shiny black spiders with a distinctive appearance.
They are a group of Australian spiders belonging to the family Atracidae. They include some of the most venomous spiders on the planet and are generally shiny black spiders with a distinctive appearance.
Despite there being around 40 species, the most well-known and notorious species is the Sydney Funnel-web (Atrax robustus). Prior to the development of the antivenom in 1980, 13 human deaths were attributed to the males of this species. Male Sydney Funnel-web have a component in their venom which the females lack. This toxin known as Robustoxin (d-Atracotoxin-Ar1) is the chemical that makes these spiders so dangerous to humans. For some unknown reason, this chemical affects primates (humans and our relatives the monkeys and apes) severely, but has relatively little effect on other mammal species. The other unfortunate part of this equation is that Australia’s most populated city was founded in the heart of this spiders’ natural habitat. Despite the distribution of these spiders and toxic venom, since the development of the antivenom the real danger of these spiders has greatly diminished. There have been no deaths as a result of Sydney Funnel-web bites in 44 years, yet the fear of these spiders remains extraordinarily high within Australia. It is certainly a case where the perceived danger far outweighs the real risk, and some perspective is required. Few people fear motor vehicles which have caused almost 88,000 deaths in Australian within the same 44 year period.
Funnel-web spiders are ambush hunters and live within silken retreats either underground, or in the case of a few species, within hollows and crevices in trees. The majority of species are found in relatively moist habitats such as shaded gullies in forested areas. Species are spread from South Australia (Adelaide Hills) through areas of Victoria, Tasmania and up the east coast into Queensland. They Sydney Funnel-web (Atrax robustus) is confined to radius of about 160km around Sydney itself. Most ground dwellers will occupy naturally occurring spaces beneath rocks and logs, and line the interior with silk. Many species have multiple entrances which are tube-like openings of silk, usually with some distinct silk strands (trip lines) connected to them. These lines alert the spider of the presence of prey when they are hunting. Insects, spiders and small vertebrates such as lizards and frogs are taken by funnel-web spiders. The prey is simply ambushed and overpowered, bitten and dragged back inside the retreat to be consumed.
