They are often found under rocks or in rock gardens, in various shrubberies, or under logs. These spiders reside in cool and relatively sheltered habitats. Funnel-web spiders get their name from their funnel-shaped burrows they spin to trap prey.

įunnel-web spiders are medium to large in size and are dark in color, ranging from black to brown (Figure 1). There has been only 1 death associated with Sydney funnel web spider bite and was likely a result of a delayed presentation 11). Moreover, the antivenom is extremely safe – no cases of anaphylaxis have been reported and only one case of serum sickness has been associated with the antivenom 10). Since the introduction of funnel web spider antivenom in 1980, there have been no deaths reported and time required in hospital has dramatically decreased from an average of 14 days 8) to less than 2 days 9). It is interesting to note that most mammals are relatively unaffected by funnel web spider venom, but humans are very sensitive. This triggers the release of excessive and eventual exhaustion of predominantly sympathetic neurotransmitters leading to the characteristic biphasic clinical syndrome 7). Delta-atracotoxins act by slowing sodium current inactivation resulting in spontaneous repetitive firing of action potentials. While the causative venom is multicomponent, the key neurotoxins are called delta-atracotoxins (delta-ACTXs) are considered to be the principal component responsible for severe envenoming in humans. In the early stages it may be mistaken for organo-phosphate poisoning. Hypertension and tachycardia occur, and respiratory distress due to rapid development of pulmonary edema, which may be very severe and potentially lethal. If envenoming occurs, it will develop early, starting with tingling around the lips, twitching of the tongue, then profuse salivation, lachrymation, sweating, piloerection and muscle twitching/spasms. The bite is usually painful, both due to large fangs and acidic venom and the spider is usually seen. However, when the spider does inject a dangerous quantity of venom, the effects can be rapid and severe, and death within an hour may occur. ĭespite its fearsome reputation, there are only 14 recorded deaths due to funnel web spider bite, and experience has shown that many bites do not result in significant envenoming. In adults, untreated envenomation may result in death from progressive, irreversible hypotension, or possibly raised intracranial pressure resulting from cerebral edema 6). other – agitation (47%), vomiting (41%), headache (10%).Ĭhildren may deteriorate rapidly and death may result in 1–2 hours if left untreated 5).noncardiogenic pulmonary edema (54%), more common in children than adults (70% compared to 44%).neurological – fasciculations (54%) and oral pins-and-needles sensation (paraesthesia) (17%).cardiovascular – hypertension (75%) and fast heart rate (tachycardia) (59%), slow heart rate (bradycardia) and hypotension (less commonly – both 10%).autonomic – excessive sweating (diaphoresis) (78%), hypersalivation (44%) and goose bumps (piloerection) (12%).Isbister et al 4) observed the following clinical effects of funnel web spider envenomation: Funnel-web spider antivenom appears effective and safe severe allergic reactions are uncommon. Of all Australian spiders, one species of the Atrax genera, the Atrax robustus also known as the Sydney funnel-web spider, is unquestionably the most dangerous spider in Australia and is implicated in the most human fatalities however tree-dwelling funnel webs (Hadronyche cerberea and Hadronyche formidabilis) have the highest envenoming rates (75%), while the Sydney funnel web, Atrax robustus, accounted for only 17% (or 1% of all spider bites) 3). There are over 40 species of funnel-web spiders, with 3 genera restricted to Australia, including the Hadronyche, Illawarra, and the Atrax 2). Funnel-web spiders are not native to the United States, although some people may keep them as exotic pets. Funnel-web spiders are found in eastern seaboard of Australia, around Sydney, including parts of southern Queensland, South Australia and Tasmania. Funnel web spider bite is a medical emergency a pressure immobilisation bandage should be applied and the patient transferred to a hospital with available antivenom and resuscitation facilities 1). Funnel web spiders are the most venomous in the world and envenomation should be considered a life threatening emergency.

Funnel of causality