Sydney Funnel-Web Spiders

The Sydney Funnel-web Spider 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, but of all these species only the Sydney Funnel-web Spider is known to be dangerous to man.

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.

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.