The Sydney Funnel-web Spider (Atrax robustus) is believed to be limited to an area of about 160 kilometres from the centre of Sydney. Other species of Funnel-Web Spider are found in Eastern Australia, Victoria, South Australia and Tasmania. They are probably the most venomous aggressive spider in the world, all funnel web species should be treated as dangerous to humans, not just the Sydney or Northern tree dweller. However, species so far proven dangerous to humans have a more limited range, largely limited to eastern parts of NSW and SE Queensland. The only proven killer, the Sydney funnel web spider, is restricted to the Sydney region and adjacent areas to the north and south of the city, including Gosford. If they bite you it is usually a pretty deep injection but even a small grazing bite means get to hospital immediately.
The Sydney Funnel-web constructs its own burrow which may be over a foot deep or uses a suitable crevice in rocks or round house foundations. Sometimes, Funnel-webs may be found in colonies of over a hundred. The webs are white and often tubular rather than funnel-like with supporting lines running out to surrounding rocks and debris.
The spiders may take several years to reach maturity and live for perhaps 8 years or longer. When mature, the males leave their webs and lead a homeless existence. They tend to roam and often enter homes particularly during Summer after a heavy downpour of rain. They mate with a female for only one season and if not killed shortly after mating, die within a few months.
This spider is one of Australia's largest and most easily identified. The body of a female Sydney Funnel-web spider measures about 35mm in length and the male about 25mm. The paired spinnerets at the end of the abdomen are particularly long, much longer than those of other large dark spiders. The male is of a more delicate build than the female and has 2 features which help identification. One is a little spur half way along its second leg on each side and the other is finely pointed feelers to transfer sperm to the female.
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Both sexes are very aggressive and when approached, will rear up into a ready-to-strike position. Their massive fangs can penetrate a child's fingernail. However, most people bitten by them are not injected with sufficient venom to cause any illness.Often it falls off the tips of the spider's fangs as it makes a preliminary downward thrust. People bitten by the female may at the most suffer pain around the bitten area.
The venom of the male is 5 times more toxic than the female. Man and monkeys seem to be especially susceptible to the venom. For example, rabbits can be given very large doses of the venom with no apparent effect but a small dose injected into a monkey produces the terrifying symptoms seen in humans. In all cases where the victim has died, and in which the spider has been positively identified, it has been a male spider.
The venom contains a low molecular weight toxin called atraxtoxin which attacks the nerves of the body causing thousands of electrical impulses to be fired down them. The muscles twitch and there is a profuse flow of perspiration, tears and saliva. The venom also causes changes to blood vessels which can lead to shock and coma due to brain damage. All the evidence suggests that the effects wear off after a few hours. Provided the victim reaches hospital before serious illness has developed, he or she has an excellent chance of recovery. An antivenom to the venom of the Sydney Funnel-web Spider became available in 1980.
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Here are some great close up photos of a female Sydney A. Robustus sent in by Colin Holliday. They were done under flash and show the colours of the spider underneath and in the leg joints as well as the extent of the hairs they have on their bodies which are not as noticeable without the flash. Photos copyright Colin Halliday. These photos may not be used except with the express permission of the owner. Please email me for his details. Click for a larger view.
Northern or Tree Dwelling Funnel-Web Spider (Atrax formidabilis)
The Northern or Tree-dwelling Funnel-web Spider is the most dangerous member of this species and near to the most dangerous in the world.They are found from northern New South Wales to southern Queensland, usually in heavily timbered areas which are rarely entered by man. A female may make her nest in a hole as high as 18 metres from the base of a tree. The venom from both males and females has shown to be more toxic than the male Sydney Funnel-web. The antivenom developed for the Sydney Funnel-web may be used effectively against the Northern Funnel-web.
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