Acanthophis

Template:Short description Template:Distinguish Template:Use dmy dates Template:Use Australian English Template:Automatic taxobox

Acanthophis is a genus of elapid snakes. Commonly called death adders, they are native to Australia, New Guinea and nearby islands, and are among the most venomous snakes in the world. Despite their common name, they are not adders at all and belong to the Elapidae family (like cobras). The name of the genus derives from the Ancient Greek Template:Transliteration/{{#invoke:Lang|lang}} ('spine') and Template:Transliteration/{{#invoke:Lang|lang}} ('snake'), referring to the spine on the death adder's tail.

Eight species are listed by ITIS,<ref name=itis>{{#if:700200 | {{#invoke:template wrapper|wrap|_template=cite web|_exclude=id,ID,taxon

 | url = https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=700200
 | title = Acanthophis 
 | publisher = Integrated Taxonomic Information System
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| Template:Citation error }}</ref> though it remains unclear how many species this genus includes, with figures ranging from 4 to 15 species being quoted.

TaxonomyEdit

French naturalist François Marie Daudin established the genus Acanthophis in 1803, with the common death adder (A. cerastinus) as its only species.<ref>Template:Cite book</ref>

Although the death adders resemble vipers of the family Viperidae, they are actually members of the family Elapidae, which includes cobras, mambas, and coral snakes.

It remains unclear how many species are included in this genus. Traditionally, only A. antarcticus, A. praelongus and A. pyrrhus have been recognised. In 1985, Wells & Wellington proposed four new species – A. armstrongi, A. hawkei, A. lancasteri, and A. schistos – but these were not widely adopted at the time.<ref>Template:Cite journal [1]</ref> In 1998 five new species were described (A. barnetti, A. crotalusei, A. cummingi, A. wellsi and A. woolfi)<ref name="Hoser1998">Hoser, R. (1998): Death adders (genus Acanthophis): an overview, including descriptions of five new species and one subspecies. Monitor 9(2): 20-30, 33-41. available online</ref> and in 2002 an additional three were described (A. groenveldi, A. macgregori and A. yuwoni).<ref name="Hoser2002">Hoser, R. (2002): Death Adders (Genus Acanthophis): An Updated overview, including descriptions of 3 New Island species and 2 New Australian subspecies. Crocodilian - Journal of the Victorian Association of Amateur Herpetologists, September 2002: 5-11, 16-22, 24-30, front and back covers. available online</ref> These were received with scepticism,<ref name="Aplin1999">Aplin, K.P. & S.C. Donnellan (1999): An extended description of the Pilbara Death Adder, Acanthophis wellsi Hoser (Serpentes: Elapidae), with notes on the Desert Death Adder, A. pyrrhus Boulenger, and identification of a possible hybrid zone. Records of the Western Australian Museum 19: 277-298.</ref><ref name="Wuster2001">Wüster, W., B. Bush, J.S. Keogh, M. O'Shea & R. Shine (2001): Taxonomic contributions in the "amateur" literature: comments on recent descriptions of new genera and species by Raymond Hoser. Litteratura Serpentium 21: 67-79, 86-91. available online (PDF) Template:Webarchive</ref><ref name="Williams2006">Williams, D., W. Wüster & B. Fry (2006): The good, the bad and the ugly: Australian snake taxonomists and a history of the taxonomy of Australia's venomous snakes. Toxicon 48: 919-930. available online (PDF) Template:Webarchive</ref> and only A. wellsi, where an extended description has been published,<ref name="Aplin1999"/> has been widely recognised.<ref name=itis/><ref name=ReptileDatabaseGenus>Reptile Database (version 10 March 2011). Acanthophis.</ref> Further confusion exists over the death adders from Papua New Guinea and Indonesia. They have variously been placed in A. antarcticus or A. praelongus. In 2005 it was shown that neither is appropriate, and the New Guinea death adders fall into two main clades:<ref name="Wuster2005"/> The rather smooth-scaled A. laevis complex (including death adders from Seram), and the rough-scaled A. rugosus complex. The latter can be divided into two sub-clades; one, A. rugosus sensu stricto, from southern New Guinea, and a second, A. hawkei, from northern Queensland and the Northern Territory in Australia. It is likely some of these include more than one species, as populations included in e.g. A. laevis show extensive variation in both pattern and scalation.<ref name="Wuster2005">Template:Cite journal</ref>

SpeciesEdit

Image	Species<ref name=itis/><ref name=ReptileDatabaseGenus/>	Authority<ref name=ReptileDatabaseGenus/>	Subspecies*	Common name	Geographic range
File:Z07 4504 export.jpg	A. antarcticus^T	(Shaw, 1794)	2<ref name=ReptileDatabaseAntarcticus>Reptile Database (version 10 March 2011). Acanthophis antarcticus.</ref>	Common death adder	Australia<ref name="Wuster2005"/>
	A. cryptamydros	Maddock, Ellis, Doughty, L.A. Smith & Wüster, 2015	0<ref name="Maddock2015">Maddock, S. T., R. J. Ellis, P. Dougthy, L. A. Smith & W. Wüster (2015): A new species of death adder (Acanthophis: Serpentes: Elapidae) from north-western Australia. Zootaxa 4007: 301–326. available online (PDF)</ref>	Kimberley death adder	Australia<ref name="Maddock2015"/><ref name="Sci-News.com">(14 Sep 2015). New Species of Venomous Snake Discovered in Australia.</ref>
	A. hawkei	Wells & Wellington, 1985	0<ref name="ReptileDatabaseHawkei"/>	Barkly Tableland death adder	Australia<ref name=ReptileDatabaseHawkei>Reptile Database (version 10 March 2011). Acanthophis hawkei.</ref>
File:Acanthophis laevis.jpg	A. laevis	Macleay, 1878	0<ref name=ReptileDatabaseLaevis>Reptile Database (version 10 March 2011). Acanthophis laevis.</ref>	Smooth-scaled death adder	Indonesia, Papua New Guinea<ref name=ReptileDatabaseLaevis/>
File:Acanthophis praelongus 1.jpg	A. praelongus	Ramsay, 1877	0<ref name=ReptileDatabasePraelongus>Reptile Database (version 10 March 2011). Acanthophis praelongus.</ref>	Northern death adder	Australia<ref name="Wuster2005"/>
File:Acanthopis pyrrhus - Christopher Watson.jpg	A. pyrrhus	Boulenger, 1898	0<ref name=ReptileDatabasePyrrhus>Reptile Database (version 10 March 2011). Acanthophis pyrrhus.</ref>	Desert death adder	Australia<ref name=ReptileDatabasePyrrhus/>
File:Acanthophis rugosus 188048029 (cropped).jpg	A. rugosus	Loveridge, 1948	0<ref name=ReptileDatabaseRugosus>Reptile Database (version 10 March 2011). Acanthophis rugosus.</ref>	Rough-scaled death adder	Australia, Indonesia<ref name=ReptileDatabaseRugosus/>
	A. wellsi	Hoser, 1998	1<ref name=ReptileDatabaseWellsi>Reptile Database (version 10 March 2011). Acanthophis wellsi.</ref>	Pilbara death adder	Australia<ref name=ReptileDatabaseWellsi/>

* Not including the nominate subspecies.
^TType species.

DescriptionEdit

File:Death-Adder.jpg

Death Adder. Photo taken at Brisbane Forest Park, Brisbane, Queensland, Australia

Death adders are very viper-like in appearance, having a short, robust body, triangular shaped heads, small subocular scales, many small scales on the top of the head, and elevated supraocular scales. Dorsal scales may be smooth or keeled. Body patterning is generally crossbanding, and they have vertically elliptical pupils.<ref name=":0">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Their fangs are also longer and more mobile than for most other elapids, although still far from the size seen in some of the true vipers. Despite their name, they are not related to adders, which are members of the family Viperidae, and their similar appearance is due to convergent evolution.

They normally take 2–3 years to reach adult size. Females are generally slightly larger than the males. They can also be easily distinguished from other Australian snakes because of a small, worm like lure on the end of their tail, which is used to attract prey. Most have large bands around their bodies, though the colour itself is variable, depending on their locality. Colours are usually black, grey or red and yellow, but also include brown and greenish-grey.

Death adders are ovoviviparous with the embryos developing in membranous sacs inside the female who will give birth to litters of 8 to 30 live neonates.<ref name=":0" />

Origin of nameEdit

Early settlers of Australia called them "deaf adders".<ref name='Etymology'>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> How "deaf" became "death" is not recorded.

Unlike other snakes that tend to flee from human disturbance, the death adder is inclined to hold its ground, leading to the notion that the death adder cannot hear. However, death adders, like other snakes, perceive ground vibrations.

HuntingEdit

Unlike most snakes, death adders do not actively hunt, but rather lie in ambush and draw their prey to them.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> When hungry, death adders bury themselves among the substrate. This may be leaf litter, soil or sand, depending on their environment. The only part of themselves they expose are their head and their tail, both generally very well camouflaged. The end of the tail is used for caudal luring and when wiggled, it is easily mistaken for a grub or worm. When the snake's prey attempts to seize it, the death adder strikes. Although it has been claimed to have the quickest strike of any snake in the world,<ref name="Strike">Template:Cite book</ref> this topic has not been well enough studied to make reliable comparisons.<ref>Template:Cite journal</ref> They commonly feed on local geckos such as the Dubious dtella.

VenomEdit

Death adders can inject on average 40–100 mg of highly toxic venom with a bite. The Template:LD50 of the venom was reported as 0.4–0.5 mg/kg subcutaneous and it is completely neurotoxic, containing neither haemotoxins nor myotoxins, unlike the venoms of most venomous snakes.

A bite from a death adder can cause paralysis which seems minor at first but can cause death from a complete respiratory shutdown in six hours. Symptoms of envenomation can be reversed through the use of death adder antivenom, or using anticholinesterases, which break the synaptic blockade by making acetylcholine more available to the parasympathetic nervous system, thus mitigating the effects of the venom.

Before antivenom was introduced, it is reported that about 50% of death adder bites were fatal. A fatal bite is less likely now as the anti-venom is widely available and the progression of envenomation symptoms is slow.

ReferencesEdit

Template:Reflist

External linksEdit

A severe case of stomatitis (canker or mouthrot) in a Death Adder (Acanthophis antarcticus) associated with a reovirus infection. Boydii (Autumn 2004):16-17. Treatment
Husbandry and breeding of Death Adders
WCH Clinical Toxinology

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