Sydney Funnel-web Spider
Sydney Funnel-web Spiders are found in the central coastal and highland regions of New South Wales. They are forest dwellers with a liking for moist, cool habitats. In the Sydney region funnel-webs are most common in the forested uplands surrounding the Cumberland Plain (NSW).Features:
These large spiders (body length 1.5 to 3.5 cm) are typically dark brown-black. The shiny carapace is almost hairless and the eyes are grouped in front. Often the abdomen is tinged with a dull reddish plum colour. At its rear end are four spinnerets, in two pairs; the larger pair is held upwards like two pointed fingers. Males are smaller-bodied and longer-legged than females, and have a conical mating spur on the underside of each second leg. Spine-like mating organs are present at the tip of short, leg-like, male palps. These palps are short, leg-like appendages which lie alongside the massive, projecting jaws, under which the dagger-like fangs are folded.Ecology/Way of Life:
These spiders make a burrow, some 15 to 35 cm deep, under or beside logs, rocks and roots in forest or gardens. The entrance to the burrow consists of a silken entrance or short passage, somewhat funnel-like in form, from which irregular silk trip-lines spread out. The slit-like opening of the entrance to the spider's silk tunnel lies collapsed on the entrance floor when not in use.
At night, these spiders hunt from the burrow entrance, running out to seize prey crossing the triplines, or foraging on the surface near the burrow. They prey on a range of animals, from insects and spiders to small frogs and lizards.
Male spiders are short-lived (3 to 4 years) compared with females (8 years or more). When males mature they leave their burrows and wander in search of females during summer and autumn. When mating, both spiders rear up head to head, the front legs braced up against each other. The male grips the bases of the female's second legs securely with his mating spurs before inserting his palpal mating organs into her genital opening. During spring and summer females make pillow-shaped egg sacs containing 80 to 250 eggs. Spiderlings disperse over summer and autumn.Interaction with Humans/Threats:
Funnel-web spiders have caused 13 deaths, all in the vicinity of Sydney. A unique combination of factors have combined to make Atrax robustus one of the world's most notorious spiders. Robustoxin (d-Atracotoxin-Ar1), the part of the venom that severely affects the nervous systems of humans and humans and other primates (but not other mammals), is present only in male spiders. This explains why male envenomation is so much more serious than that of females. The highly venomous male spiders are more likely to come into contact with people because of their active wandering behaviour, some even entering houses. Also the distribution of this spider coincides with that of almost 5 million people in the Wollongong, Sydney and Newcastle regions. Fortunately, an effective antivenom was introduced in 1981 (the last death was in 1980), but the rapid application of proper first aid, such as the pressure-immobilisation first aid technique, remains essential.
Nerve toxins from the funnel-web spider venom of this spider are under investigation as effective targeted biopesticides. Genes for Sydney Funnel-web Spider nerve neurotoxins that kill insects are being introduced experimentally into viruses that infect specific insect pests. Once infected, the cells of these insects produce the neurotoxin, which kills them rapidly.Other Comments:
The Sydney Funnel-web Spider was described by O.P.Cambridge in 1877. The origin of the name Atrax is uncertain, but may derive from the Latin atrare = to blacken or atrox = terrible; the species name is from the Latin robustus = strong or powerful.Further Reading:
The pressure-immobilisation technique is described at: http://www.usyd.edu.au/su/anaes/snakebite.html#SNAKEFIRSTAID.
Bradley, R.A. (1993). Seasonal activity patterns in Sydney funnel-web spiders, Atrax spp. (Araneae: Hexathelidae). Bulletin of the British Arachnological Society 9 (6): 189-192.
Gray, M.R. (1987). Distribution of the funnelweb spiders. In Covacevitch, J., Davie, P. and Pearn, J. (eds), Toxic Plants and Animals. A Guide for Australia. Queensland Museum, Brisbane.
Gray, M.R. (1992). Funnelwebs: separating fact from fiction. Australian Natural History 24: 34-39.
McGhee, K. (1999). Funnel-webs. Australian Geographic 53: 80-95.
Robins, M. and Le Page, M. (2000). Mean and green - Does a deadly spider hold the key to eco-pesticides? New Scientist, 17 June, No. 2243: 5.
Sutherland, S.K. and J. Tibballs (2001). Australian Animal Toxins. The creatures, their toxins and care of the poisoned patient. Oxford University Press.
Wilson, D. and Alewood, P. (2000). Fascinating Funnel-web findings. Today's Life Science 12 (4): 28-33.Topics: Spider webs Venom Prey capture
Text & map by Mike Gray; photograph by Mike Gray, courtesy of the Australian Museum.Sponsorship welcomed:
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