Acanthophis
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''Acanthophis'' is a
genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of
elapid Elapidae (, commonly known as elapids , from , variant of "sea-fish") is a family (biology), family of snakes characterized by their permanently erect fangs at the front of the mouth. Most elapids are venomous, with the exception of the genus ...
snake Snakes are elongated limbless reptiles of the suborder Serpentes (). Cladistically squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales much like other members of the group. Many species of snakes have s ...
s. Commonly called ''death adders'', they are native to
Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...
,
New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; , fossilized , also known as Papua or historically ) is the List of islands by area, world's second-largest island, with an area of . Located in Melanesia in the southwestern Pacific Ocean, the island is ...
and nearby islands, and are among the most
venomous snake ''Venomous snakes'' are species of the suborder Serpentes that are capable of producing venom, which they use for killing prey, for defense, and to assist with digestion of their prey. The venom is typically delivered by injection using hollow ...
s in the world. Despite their common name, they are not adders at all and belong to the
Elapidae Elapidae (, commonly known as elapids , from , variant of "sea-fish") is a family of snakes characterized by their permanently erect fangs at the front of the mouth. Most elapids are venomous, with the exception of the genus '' Emydocephalus ...
family (like
cobra COBRA or Cobra, often stylized as CoBrA, was a European avant-garde art group active from 1948 to 1951. The name was coined in 1948 by Christian Dotremont from the initials of the members' home countries' capital cities: Copenhagen (Co), Brussels ...
s). The name of the genus derives from the
Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...
/ ('spine') and / ('snake'), referring to the spine on the death adder's tail. Eight species are listed by
ITIS The Integrated Taxonomic Information System (ITIS) is an American partnership of federal agencies designed to provide consistent and reliable information on the taxonomy of biological species. ITIS was originally formed in 1996 as an interagenc ...
, though it remains unclear how many
species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
this genus includes, with figures ranging from 4 to 15 species being quoted.


Taxonomy

French naturalist
François Marie Daudin François Marie Daudin (; 29 August 1776 in Paris – 30 November 1803 in Paris) was a French zoologist. Biography With legs paralyzed by childhood disease, he studied physics and natural history but ended up being devoted to the latter. Daudin w ...
established the genus ''Acanthophis'' in 1803, with the common death adder (''A. cerastinus'') as its only species. Although the death adders resemble vipers of the family
Viperidae Vipers are snakes in the family Viperidae, found in most parts of the world, except for Antarctica, Australia, Hawaii, Madagascar, New Zealand, Ireland, and various other isolated islands. They are venomous snake, venomous and have long (relat ...
, they are actually members of the family
Elapidae Elapidae (, commonly known as elapids , from , variant of "sea-fish") is a family of snakes characterized by their permanently erect fangs at the front of the mouth. Most elapids are venomous, with the exception of the genus '' Emydocephalus ...
, which includes
cobra COBRA or Cobra, often stylized as CoBrA, was a European avant-garde art group active from 1948 to 1951. The name was coined in 1948 by Christian Dotremont from the initials of the members' home countries' capital cities: Copenhagen (Co), Brussels ...
s,
mamba Mambas are fast-moving, highly venomous snakes of the genus ''Dendroaspis'' (which literally means "tree asp") in the family Elapidae. Four extant species are recognised currently; three of those four species are essentially arboreal and gre ...
s, and
coral snake Coral snakes are a large group of elapid snakes that can be divided into two distinct groups, the Old World coral snakes and New World coral snakes. There are 27 species of Old World coral snakes, in three genera ('' Calliophis'', '' Hemibungar ...
s. It remains unclear how many
species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
are included in this
genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
. 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. In 1998 five new species were described (''A. barnetti'', ''A. crotalusei'', ''A. cummingi'', ''A. wellsi'' and ''A. woolfi'') 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'').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

/ref> These were received with scepticism,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. 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)
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)
and only ''A. wellsi'', where an extended description has been published, has been widely recognised.Reptile Database (version 10 March 2011).
Acanthophis
''
Further confusion exists over the death adders from
Papua New Guinea Papua New Guinea, officially the Independent State of Papua New Guinea, is an island country in Oceania that comprises the eastern half of the island of New Guinea and offshore islands in Melanesia, a region of the southwestern Pacific Ocean n ...
and
Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...
. 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
clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...
s: The rather smooth-scaled ''A. laevis''
complex Complex commonly refers to: * Complexity, the behaviour of a system whose components interact in multiple ways so possible interactions are difficult to describe ** Complex system, a system composed of many components which may interact with each ...
(including death adders from
Seram Seram (formerly spelled Ceram; also Seran or Serang) is the largest and main island of Maluku province of Indonesia, despite Ambon Island's historical importance. It is located just north of the smaller Ambon Island and a few other adjacent i ...
), and the rough-scaled ''A. rugosus'' complex. The latter can be divided into two sub-clades; one, ''A. rugosus
sensu stricto ''Sensu'' is a Latin word meaning "in the sense of". It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular c ...
'', from southern
New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; , fossilized , also known as Papua or historically ) is the List of islands by area, world's second-largest island, with an area of . Located in Melanesia in the southwestern Pacific Ocean, the island is ...
, and a second, ''A. hawkei'', from northern
Queensland Queensland ( , commonly abbreviated as Qld) is a States and territories of Australia, state in northeastern Australia, and is the second-largest and third-most populous state in Australia. It is bordered by the Northern Territory, South Austr ...
and the
Northern Territory The Northern Territory (abbreviated as NT; known formally as the Northern Territory of Australia and informally as the Territory) is an states and territories of Australia, Australian internal territory in the central and central-northern regi ...
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 In zoology, a scale (; ) is a small rigid plate made out of keratin that grows out of Vertebrate animals' skin to provide protection. In lepidopterans (butterflies and moths), scales are plates on the surface of the insect wing, made out of chi ...
.


Species

* Not including the
nominate subspecies In biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics ( morphology), but that can successfully interbreed. ...
.
T
Type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...
.


Description

Death adders are very
viper Vipers are snakes in the family Viperidae, found in most parts of the world, except for Antarctica, Australia, Hawaii, Madagascar, New Zealand, Ireland, and various other isolated islands. They are venomous and have long (relative to non-vipe ...
-like in appearance, having a short, robust body,
triangular A triangle is a polygon with three corners and three sides, one of the basic shapes in geometry. The corners, also called ''vertices'', are zero-dimensional points while the sides connecting them, also called ''edges'', are one-dimensional ...
shaped heads, small subocular scales, many small scales on the top of the head, and elevated
supraocular scales In scaled reptiles, supraocular scales are (enlarged) scales on the crown immediately above the eye.Mallow D, Ludwig D, Nilson G. 2003. True Vipers: Natural History and Toxinology of Old World Vipers. Malabar, Florida: Krieger Publishing Company. ...
. Dorsal scales may be smooth or keeled. Body patterning is generally crossbanding, and they have vertically elliptical
pupil The pupil is a hole located in the center of the iris of the eye that allows light to strike the retina.Cassin, B. and Solomon, S. (1990) ''Dictionary of Eye Terminology''. Gainesville, Florida: Triad Publishing Company. It appears black becau ...
s. 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 Vipers are snakes in the family Viperidae, found in most parts of the world, except for Antarctica, Australia, Hawaii, Madagascar, New Zealand, Ireland, and various other isolated islands. They are venomous snake, venomous and have long (relat ...
, and their similar appearance is due to
convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last comm ...
. 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 Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a "bridging" form of reproduction between egg-laying oviparity, oviparous and live-bearing viviparity, viviparous reproduction. Ovoviviparous animals possess embryos that develo ...
with the embryos developing in membranous sacs inside the female who will give birth to litters of 8 to 30 live neonates.


Origin of name

Early settlers of Australia called them "deaf adders". 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.


Hunting

Unlike most snakes, death adders do not actively hunt, but rather lie in ambush and draw their prey to them. When hungry, death adders bury themselves among the
substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached ** Substrate (aquatic environment), the earthy material that exi ...
. This may be
leaf litter Plant litter (also leaf litter, tree litter, soil litter, litterfall, or duff) is dead plant material (such as leaves, bark, needles, twigs, and cladodes) that has fallen to the ground. This detritus or dead organic material and its constituen ...
, 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 Caudal luring is a form of aggressive mimicry characterized by the waving or wriggling of the predator's tail to attract prey. This movement attracts small animals who mistake the tail for a small worm or other small animal. When the animal approac ...
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, this topic has not been well enough studied to make reliable comparisons. They commonly feed on local geckos such as the
Dubious dtella The dubious dtella, native Australian house gecko, or dubious four-clawed gecko (''Gehyra dubia'') is a species of gecko in the genus ''Gehyra'', native to Northeastern Australia (Queensland and northern New South Wales as well as islands of the G ...
.


Venom

Death adders can inject on average 40–100 mg of highly
toxic Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subst ...
venom with a bite. The of the venom was reported as 0.4–0.5 mg/kg subcutaneous and it is completely
neurotoxic Neurotoxicity is a form of toxicity in which a biological, chemical, or physical agent produces an adverse effect on the structure or function of the central and/or peripheral nervous system. It occurs when exposure to a substance – specifical ...
, containing neither haemotoxins nor
myotoxin Myotoxins are small, basic peptides found in snake venoms (e.g. rattlesnakes) and lizard venoms (e.g. Mexican beaded lizard). This involves a non-enzymatic mechanism that leads to severe muscle necrosis. These peptides act very quickly, causing i ...
s, unlike the venoms of most venomous snakes. A bite from a death adder can cause
paralysis Paralysis (: paralyses; also known as plegia) is a loss of Motor skill, motor function in one or more Skeletal muscle, muscles. Paralysis can also be accompanied by a loss of feeling (sensory loss) in the affected area if there is sensory d ...
which seems minor at first but can cause death from a complete
respiratory The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies gr ...
shutdown in six hours. Symptoms of envenomation can be reversed through the use of death adder
antivenom Antivenom, also known as antivenin, venom antiserum, and antivenom immunoglobulin, is a specific treatment for envenomation. It is composed of antibodies and used to treat certain venomous bites and stings. Antivenoms are recommended only if ...
, or using
anticholinesterase Cholinesterase inhibitors (ChEIs), also known as anti-cholinesterase, are chemicals that prevent the breakdown of the neurotransmitter acetylcholine or butyrylcholine by cholinesterase. This increases the amount of the acetylcholine or butyryl ...
s, which break the synaptic
blockade A blockade is the act of actively preventing a country or region from receiving or sending out food, supplies, weapons, or communications, and sometimes people, by military force. A blockade differs from an embargo or sanction, which are ...
by making
acetylcholine Acetylcholine (ACh) is an organic compound that functions in the brain and body of many types of animals (including humans) as a neurotransmitter. Its name is derived from its chemical structure: it is an ester of acetic acid and choline. Par ...
more available to the
parasympathetic nervous system The parasympathetic nervous system (PSNS) is one of the three divisions of the autonomic nervous system, the others being the sympathetic nervous system and the enteric nervous system. The autonomic nervous system is responsible for regulat ...
, 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 Anti-Venom is a fictional antihero appearing in Comic books published by Marvel Comics. It first appeared in ''The Amazing Spider-Man'' #569 (August 2008), and was created by Dan Slott and John Romita Jr. The creature belongs to a race of amorp ...
is widely available and the progression of envenomation symptoms is slow.


References


Further reading

* Daudin FM (1803). ''Histoire Naturelle, Générale et Particulière des Reptiles; Ouvrage faisant suite aux Œuvres de Leclerc de Buffon, et partie du Cours complet d'Histoire naturelle rédigé par C.S. Sonnini, membre de plusieurs Sociétés savantes. Tome Cinquième'' olume 5 Paris: F. Dufart. 365 pp. (''Acantophis'', new genus, pp. 287–288). (in French).


External links

*A severe case of stomatitis (canker or mouthrot) in a Death Adder (''Acanthophis antarcticus'') associated with a reovirus infection. Boydii (Autumn 2004):16-17
TreatmentWCH Clinical Toxinology
{{Authority control Snakes of Australia Venomous snakes Snake genera Taxa named by François Marie Daudin