Australasian funnel-web spider
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2008-07-12T10:36:06Z
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/* Description */
{{refimprove|date=July 2008}}
{{Taxobox
| name = Venomous funnel-web spiders
| image = Victorian funnelweb02.jpg
| image_width = 210px
| image_caption = '''''Atrax robustus'''''
| regnum = [[Animal]]ia
| phylum = [[Arthropoda]]
| classis = [[Arachnida]]
| ordo = [[Araneae]]
| subordo = [[Mygalomorphae]]
| familia = [[Hexathelidae]]
| familia_authority = [[Eugène Simon|Simon]], 1892
| subdivision_ranks = '''Genera'''
| subdivision =
''Atrax''<br />
''Hadronyche''<br />
}}
'''Australasian funnel-web spiders''' are very venomous [[spider]]s of the family ''[[Hexathelidae]]''. These spiders are found in two genera of the family: ''Hadronyche'' (which is not associated with any known human fatalities) and ''Atrax'' [http://www.austmus.gov.au/spiders/dangerous/funnelweb/index.htm (which probably have killed 13 people)]. They are notorious for the inclusion of the Sydney funnel-web spider (''Atrax robustus''), native to eastern [[Australia]]. There are other genera in family ''Hexathelidae'', but these do not have the notorious reputation of the Australasian funnel-webs.
== Description ==
These spiders are medium-to-large in size, with body lengths ranging from 1 cm to 5 cm (0.4" to 2"). They are darkly coloured, ranging from black to brown, with a glossy carapace covering the front part of the body. Some of these spiders greatly resemble [[tarantulas]]. Like the related [[Funnel-web tarantula|diplurid]] spiders, the hexathelids generally have long [[spinnerets]]; this is especially true of ''A. robustus''.
Like other [[Mygalomorphae]], (also called the ''Orthognatha'' an [[infraorder]] of [[spider]]s that includes the so-called [[tarantula]]s- (Mygalomorph tarantulas are more correctly termed "bird-eating spiders"- the true 'tarantula' is an araneomorph Lycosid from Europe <ref>Rod and Ken Preston-Mafham. Spiders of the World. Blandford Press, 1989, England. Page 47</ref>)) , these spiders have [[fang]]s which point straight down and do not cross each other (cf [[Araneomorphae]]). They have ample [[venom]] glands that lie entirely within their [[chelicerae]]. Their fangs are large and powerful. Although they are fairly small compared to the Mygalomorph [[tarantula]]s, they should not be handled without taking substantial precautions, because their fangs have been known to penetrate fingernails and soft shoes, resulting in a dangerous bite.
==Habitat==
[[Image:funnel_web_spider_den2.jpg|thumb|right|210px|funnel web spider burrow - mount glorious, queensland]]
The primary range of the Australasian funnel-web spiders is the eastern coast of [[Australia]], with specimens found in [[New South Wales]], [[South Australia]], [[Victoria (Australia)|Victoria]], and [[Queensland]]. In addition, some specimens have been found in other islands in the south Pacific. The only Australian state that lacks a funnel-web population is Western Australia. <ref> Raymond Mascord- Australian Spiders in Colour. Reed Press, 1991, NSW. Page 14 </ref>
== Medical significance ==
Funnel-webs are probably one of the three most dangerous spiders in the world and are regarded by some to be the most dangerous.<ref name="MJA2005-Isbister">{{cite journal | author = Isbister G, Gray M, Balit C, Raven R, Stokes B, Porges K, Tankel A, Turner E, White J, Fisher M | title = Funnel-web spider bite: a systematic review of recorded clinical cases | journal = Med J Aust | volume = 182 | issue = 8 | pages = 407–11 | year = 2005 | pmid = 15850438}}</ref>
Examination of [[spider bite|bite]] records seems to indicate that wandering [[male]]s have caused a large majority of fatal bites to humans, however this has not been proven. Males, recognised by the modified terminal segment of the [[Pedipalp|palp]], are aggressive and tend to wander during the warmer months of the year looking for receptive females of their kind for [[Sexual intercourse|mating]].<ref>{{cite journal | author = Isbister G, Gray M | title = Bites by Australian mygalomorph spiders (Araneae, Mygalomorphae), including funnel-web spiders (Atracinae) and mouse spiders (Actinopodidae: Missulena spp) | journal = Toxicon | volume = 43 | issue = 2 | pages = 133–40 | year = 2004 | pmid = 15019472 | doi = 10.1016/j.toxicon.2003.11.009}}</ref> They are attracted to water and hence are often found in swimming pools where they have fallen while wandering. The spiders can survive such immersion for several hours and can deliver a bite when removed from the water, so this should not be done by hand.<ref>Mike Gray: "The Distribution of Funnel-Web Spiders in Australia" in Toxic Plants and Animals: A Guide for Australia. Queensland Museum Press, 1987. Page 313-22</ref>. They also show up in garages and yards in suburban [[Sydney]]. Contrary to public opinion, no funnel-web spider is able to jump, although they can run swiftly. <ref>Mark Gray- "The Distribution of Funnel-Web Spiders in Australia. In Toxic Plants and Animals: A Guide for Australia. Queensland Museum Press, 1987. Page 313-322. </ref>
While some very venomous spiders may give dry bites, these spiders do so much less frequently. It appears that approximately 10% to 25% of bites will produce toxicity<ref name="MJA2005-Isbister"/> but the likelihood cannot be predicted and all should be treated as potentially life-threatening.
There have been 26 recorded deaths in Australia in the last 100 years from spider bites. Bites from funnel web spiders have caused 13 deaths (seven in children)<ref name="MJA2005-Isbister"/>. In all cases where the sex of the biting spider could be determined, it was found to be the male of the species.<ref name="ClinExp2002-Nicholson">{{cite journal | author = Nicholson G, Graudins A | title = Spiders of medical importance in the Asia-Pacific: atracotoxin, latrotoxin and related spider neurotoxins | journal = Clin Exp Pharmacol Physiol | volume = 29 | issue = 9 | pages = 785–94 | year = 2002 | pmid = 12165044 | doi = 10.1046/j.1440-1681.2002.03741.x}}</ref> Most victims were young, ill or infirm. Members of the genus ''Hadronyche'' may also cause fatal envenomations although none has been recorded. Assays of venom from several ''Hadronyche'' species have shown it to be similar to ''Atrax'' venom.
===Toxins===
There are a large number of different [[toxin]]s in the venom of ''Atrax'' and ''Hadronyche'' spiders. Collectively, the toxins are given the name [[Spider toxin|atracotoxins (ACTX)]], as all these spiders belong to the subfamily Atracinae. The first toxins isolated were the δ-ACTX toxins present in the venom of both ''A. robustus'' ('''δ-ACTX-Ar1''', formerly known as [[robustoxin]]) and ''H. versuta'' ('''δ-ACTX-Hv1a''', formerly known as '''versutoxin'''). Both these toxins produce the same funnel-web envenoming syndrome in monkeys as that seen in humans, suggesting that they are responsible for the physiological effects seen with crude venom.<ref name="ClinExp2002-Nicholson"/>
[[Image:Atrax robustus.jpg|thumb|left|210px|Female Sydney funnel-web spider]]
These toxins are thought to operate by opening [[sodium channel]]s. They are [[presynaptic]] [[neurotoxin]]s that (via sodium channels) induce spontaneous, repetitive firing of [[action potentials]] in autonomic and motor neurons and inhibit neurally mediated transmitted release resulting in a surge of endogenous [[acetylcholine]], [[noradrenaline]] and [[adrenaline]].<ref>{{cite journal | author = Harris J, Sutherland S, Zar M | title = Actions of the crude venom of the Sydney funnel-web spider. Atrax robustus on autonomic neuromuscular transmission | journal = Br J Pharmacol | volume = 72 | issue = 2 | pages = 335–40 | year = 1981 | pmid = 6260279}}</ref>
Although extremely toxic to primates, the venom appears to be fairly harmless to many other animals, including [[dog]]s, [[cat]]s, [[horse]]s, [[rabbit]]s, [[guinea-pig]]s, [[chicken]]s and even [[cane toad]]s. It has been suggested that these animals may be resistant to the venom's effects due to the presence of [[IgG]], and possibly cross-linked IgG and [[IgM]] inactivating factors in their [[blood plasma]] that bind to the toxins responsible and neutralise them, or it may involve a non-specific reaction due to the highly basic nature of the toxins.<ref>{{cite journal | author = Sheumack D, Comis A, Claassens R, Mylecharane E, Spence I, Howden M | title = An endogenous antitoxin to the lethal venom of the funnel web spider, Atrax robustus, in rabbit sera | journal = Comp Biochem Physiol C | volume = 99 | issue = 1-2 | pages = 157–61 | year = 1991 | pmid = 1675965 | doi = 10.1016/0742-8413(91)90093-9}}</ref>
The [[female]] [[Venom (poison)|venom]] was thought to be only about a sixth as potent to humans as that of the male<ref>{{cite journal | author = Wiener S | title = The Sydney funnel-web spider (Atrax robustus): II. Venom yield and other characteristics of spider in captivity | journal = Med J Aust | volume = 46(2) | issue = | pages = 678–82 | year = | pmid = 13844638}}</ref> but recent research has proven that false. The bite of a female or juvenile may be serious; however, considerable variability occurs in venom toxicity between species.
===Symptoms===
The envenoming syndromes observed following bites by all these spiders are identical. The bite is initially very painful due to the [[acidity]] of the venom and the size of the fangs penetrating the skin. Systemic envenoming may follow the local effects. Early symptoms of systemic envenoming include tingling around the mouth and tongue, facial muscle twitching, nausea, vomiting, profuse sweating, salivation, and [[dyspnoea|shortness of breath]]. Patients may rapidly develop [[agitation]], [[confusion]] and [[coma]] associated with [[hypertension]], [[metabolic acidosis]], [[mydriasis|dilation of the pupils]], generalised muscle twitching and [[pulmonary oedema]].<ref name="MJA2005-Isbister"/> Death results from progressive [[hypotension]] or possibly raised [[intracranial pressure]] resulting from [[cerebral oedema]].<ref>{{cite journal | author = Torda T, Loong E, Greaves I | title = Severe lung oedema and fatal consumption coagulopathy after funnel-web bite | journal = Med J Aust | volume = 2 | issue = 8 | pages = 442–4 | year = 1980 | pmid = 7010098}}</ref>
The onset of severe envenoming is rapid; in one prospective study, the median time to onset of envenoming was 28 minutes, with only two cases having onset after 2 hours (both had pressure immobilization bandages applied).<ref name="MJA2005-Isbister"/> Deaths may occur within a period ranging from 15 minutes<ref name="ClinExp2002-Nicholson"/> (this occurred when a small child was bitten) to three days.
===Treatment===
First aid for funnel-web bites consists of applying a pressure immobilization bandage. Pressure immobilization is the wrapping of the bitten limb with a crepe bandage and splint. It was originally developed for [[snakebite]]s but has been shown to be effective at slowing venom movement in funnel web bites and may also slowly inactivate the venom.<ref>{{cite journal | author = Sutherland S, Duncan A | title = New first-aid measures for envenomation: with special reference to bites by the Sydney funnel-web spider (Atrax robustus) | journal = Med J Aust | volume = 1 | issue = 8 | pages = 378–9 | year = 1980 | pmid = 6771503}}</ref>
[[Image:Victorian funnelweb_side.jpg|thumb|right|210|''A. robustus'']] Further supportive care may be necessary, but the mainstay of treatment is [[antivenom]]. Antivenom is raised against male ''Atrax robustus'' venom but appears to be effective for all species of funnel web spiders.<ref>{{cite journal | author = Graudins A, Wilson D, Alewood P, Broady K, Nicholson G | title = Cross-reactivity of Sydney funnel-web spider antivenom: neutralization of the in vitro toxicity of other Australian funnel-web (Atrax and Hadronyche) spider venoms | journal = Toxicon | volume = 40 | issue = 3 | pages = 259–66 | year = 2002 | pmid = 11711122 | doi = 10.1016/S0041-0101(01)00210-0}}</ref> Funnel-web antivenom has also been shown to reverse the in vitro effects of Eastern [[Mouse spider]] (''Missulena bradleyi'') venom.<ref>{{cite journal | author = Rash L, Birinyi-Strachan L, Nicholson G, Hodgson W | title = Neurotoxic activity of venom from the Australian eastern mouse spider (Missulena bradleyi) involves modulation of sodium channel gating | journal = Br J Pharmacol | volume = 130 | issue = 8 | pages = 1817–24 | year = 2000 | pmid = 10952670 | doi = 10.1038/sj.bjp.0703494}}</ref>
Prior to the introduction of [[antivenom]], envenoming resulted in significant morbidity and mortality.<ref>{{cite journal | author = Isbister G, Graudins A, White J, Warrell D | title = Antivenom treatment in arachnidism | journal = J Toxicol Clin Toxicol | volume = 41 | issue = 3 | pages = 291–300 | year = 2003 | pmid = 12807312 | doi = 10.1081/CLT-120021114}}</ref> The purified rabbit [[IgG]] antivenom was developed in 1981 through a team effort led by Dr [[Struan Sutherland]], head of immunology at the [[CSL Limited|Australian Commonwealth Serum Laboratories]] in [[Melbourne]].<ref>{{cite journal | author = Fisher M, Raftos J, McGuinness R, Dicks I, Wong J, Burgess K, Sutherland S | title = Funnel-web spider (Atrax robustus) antivenom. 2. Early clinical experience | journal = Med J Aust | volume = 2 | issue = 10 | pages = 525–6 | year = 1981 | pmid = 7321948}}</ref> Fortunately, the antivenom is fast-acting and highly and globally effective.<ref>{{cite journal | author = Hartman L, Sutherland S | title = Funnel-web spider (Atrax robustus) antivenom in the treatment of human envenomation | journal = Med J Aust | volume = 141 | issue = 12-13 | pages = 796–9 | year = | pmid = 6503783}}</ref> Antivenom therapy has shortened the course of envenoming: prior to antivenom availability, the average length of hospital treatment for severe bites was about 14 days. Today, antivenom-treated patients are commonly discharged from hospital within 1 to 3 days.<ref name="ClinExp2002-Nicholson"/> There have been no deaths since it became available.<ref name="MJA2005-Isbister"/>
While all funnel-web bites appear to have been by male spiders, none of the 13 victims has been an adult male. The 13th and last victim was a two-year-old boy, James Culley, who was bitten on 3 January 1980 and died three days later. <ref> Mark Whittaker, ''Spiderman'', an article about [[Struan Sutherland]], ''[[The Weekend Australian]]'' magazine, 13-14 March 1999</ref>
==Species==
The following funnel-web species have been identified:
* ''Atrax robustus'', [[Sydney]] funnel-web spider
* ''Hadronyche adelaidensis'', [[Adelaide]] funnel-web spider
* ''Hadronyche cerberea'', Tree funnel-web spider or Southern funnel-web spider
* ''Hadronyche eyrei'', [[Eyre Peninsula]] funnel-web spider
* ''Hadronyche flindersi'', [[Flinders]] funnel-web spider
* ''[[Northern funnel-web spider|Hadronyche formidabilis]]'', Northern Rivers funnel-web spider or Northern funnel-web spider
* ''Hadronyche infensa'', Toowoomba funnel-web spider or [[Fraser Island]] funnel-web spider.
* ''Hadronyche modesta'', [[Victoria (Australia)|Victoria]]n funnel-web spider
* ''Hadronyche pulvinator'', Cascade funnel-web spider
* ''Hadronyche venenata'', [[Tasmania]]n funnel-web spider
* ''Hadronyche versuta'', [[Blue Mountains (Australia)|Blue Mountains]] funnel-web spider
:See [[List of Hexathelidae species]] for a complete list of species within this family (about 90 species in 11 genera).
==Footnotes==
<div class="references-small">
<references />
</div>
==References==
* [http://www.mja.com.au/public/issues/182_08_180405/isb10564_fm.html Medical information regarding bites and geographical ranges]
* Main, Barbara York. 1976. ''Spiders''. Collins, Sydney, Australia.
* McKeown, Keith C. 1952. ''Australian Spiders''. Angus and Robertson, Sydney, Australia.
* [http://www.amonline.net.au/spiders/dangerous/funnelweb/ Spiders. Funnel-Web Spiders. Family Hexathelidae]
* [http://news.bbc.co.uk/1/hi/health/3539410.stm BBC News: Scapegoats For Diseases] 6th August 2004.
* [http://www.washington.edu/burkemuseum/spidermyth/myths/downunder.html Spider Myths: Ours Are Deadlier Than Yours]
==External links==
{{Commons|Hexanthelidae|Australasian funnel-web spider}}
{{Wikispecies|Hadronyche}}
* [http://www.arachnology.org/Arachnology/Pages/Araneae.html Arachnology Home Pages: Araneae]
* [http://www.arachnology.org/Arachnology/Pages/Atrax.html Arachnology Home Pages: Atrax]
* [http://research.amnh.org/entomology/spiders/catalog81-87/index.html Platnick, N.I. 2003. World Spider Catalog]
* [http://www.amonline.net.au/factsheets/funnelweb.htm Funnel-web spider info]
* [http://www.deh.gov.au/cgi-bin/species-bank/sbank-treatment.pl?id=75618 Information, distribution and pictures of ''A. robustus'']
[[Category:Funnel-web spiders]]
[[Category:Hexathelidae]]
[[Category:Spiders of Australia]]
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[[fr:Hexathelidae]]
[[hr:Sidnejski pogrebni pauk]]
[[he:עכביש המשפך האוסטרלי]]
[[pl:Ptasznik australijski]]