Black mamba: Difference between revisions
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a very large, black weiner |
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{{Other uses}} |
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{{Taxobox |
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| name = Black mamba |
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| image = Dendroaspis polylepis by Bill Love.jpg |
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| image_caption = A black mamba in a defensive posture |
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| status = LC |
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| status_ref = <ref name='ICUN'/> |
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| status_system = iucn3.1 |
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| regnum = [[Animal]]ia |
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| phylum = [[Chordate|Chordata]] |
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| classis = [[Reptile|Reptilia]] |
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| ordo = [[Squamata]] |
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| subordo = [[Serpentes]] |
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| familia = [[Elapidae]] |
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| genus = ''[[Dendroaspis]]'' |
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| species = '''''D. polylepis''''' |
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| binomial = ''Dendroaspis polylepis'' |
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| binomial_authority = [[Albert Günther|Günther]], 1864<ref name="ITIS"/><ref name=Database/> |
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| range_map = D.polylepis range.png |
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| range_map_width = |
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| range_map_caption = In orange, range of ''D. polylepis'' <br>In green, ''D. polylepis'' may or may not occur here |
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| synonyms_ref = <ref name=Database/> |
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| synonyms = |
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*''Dendroaspis polylepis polylepis'' <br/><small>Günther, 1864</small> |
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*''Dendraspis polylepis'' <br/><small>Günther, 1864</small> |
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*''Dendraspis angusticeps'' <br/><small>Boulenger 1896</small> |
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*''Dendraspis antinorii'' <br/><small>Peters, 1873</small> |
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*''Dendroaspis polylepis antinorii'' <br/><small>(Peters, 1873)</small> |
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}} |
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The '''black mamba''' (''Dendroaspis polylepis''), also called the '''common black mamba''' or '''black-mouthed mamba''',<ref name=WCH>{{cite web|title=Dendroaspis polylepis – General Details, Taxonomy and Biology, Venom, Clinical Effects, Treatment, First Aid, Antivenoms|url=http://www.toxinology.com/fusebox.cfm?fuseaction=main.snakes.display&id=SN0170|work=WCH Clinical Toxinology Resource|publisher=University of Adelaide|accessdate=2 December 2011}}</ref> is the longest [[venomous snake]] in [[Africa]], averaging around {{convert|2.5|to|3.2|m|ft|abbr =on}} in length, and sometimes growing to lengths of {{convert|4.45|m|abbr =on}}.<ref name='Marais'/> It is named for the black colour of the inside of the mouth rather than the colour of its scales which varies from dull yellowish-green to a gun-metal grey. It is also the fastest snake in the world, capable of moving at 4.32 to 5.4 metres per second (16–20 km/h, 10–12 mph).<ref name='NG'/> The black mamba has a reputation for being very aggressive, but it usually attempts to flee from humans like most snakes, unless it is threatened.<ref name=Oshea05/> Without rapid and vigorous [[antivenom]] therapy, a bite from a black mamba is almost always fatal.<ref name=Oshea05/><ref name='Territory'/><ref name='Davidson'/> |
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==Taxonomy== |
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The black mamba was first described in 1864 by [[Albert Günther]], a German-born British [[Zoology|zoologist]], [[Ichthyology|ichthyologist]], and [[Herpetology|herpetologist]]. Soon after, a subspecies was identified, ''Dendroaspis polylepis antinorii'' (Peters, 1873), but this is no longer accepted as distinct.<ref name="ITIS">{{ITIS |id=700483 |taxon=''Dendroaspis polylepis'' |accessdate=2 December 2011}}</ref><ref name=Database>{{cite web|last=Uetz|first=Peter|title=Dendroaspis polylepis GÜNTHER, 1864|url=http://reptile-database.reptarium.cz/species?genus=Dendroaspis&species=polylepis|work=Reptile Database|publisher=Zoological Museum Hamburg|accessdate=2 December 2011}}</ref> The genus and species name are derived from [[Ancient Greek]] words – ''Dendroaspis'' meaning "tree asp" (''dendro'' is "tree", while ''aspis'' is "asp" which is understood to mean a "venomous snake") and ''polylepis'', "many scaled", from ''poly'' "many" and ''lepis'' "scales".<ref>{{cite journal|last=Rauchenberger|first=Mary|title=A New Species of Allodontichthys (Cyprinodontiformes: Goodeidae), with Comparative Morphometrics for the Genus|journal=Copeia – American Society of Ichthyologists and Herpetologists|date=18|year=1988|volume=2|pages=433–441|doi=10.2307/1445884|url=http://www.goodeidworkinggroup.com/Allodontichthys-polylepis|accessdate=2 December 2011}}</ref><ref>[http://hardyfernlibrary.com/ferns/listspecies.cfm?auto=40 Hardy Fern Library – polylepis etymology]. Hardyfernlibrary.com. Retrieved on 2012-07-08.</ref> The name "black mamba" is given to the snake not because of its body colour but because of the ink-black colouration of the inside of its mouth, which it displays when threatened.<ref name='NG'/> In 1896, [[George Albert Boulenger|Boulenger]] combined the species (''Dendroaspis polylepis'') as a whole with the [[eastern green mamba]], ''Dendroaspis angusticeps'', and they were considered a single species from 1896<ref>[[George Albert Boulenger|Boulenger, G.A.]] 1896. ''Catalogue of the Snakes in the British Museum (Natural History), Volume III''. ASIN: B004II92FO. London. p. 437. [http://www.amazon.com/Catalogue-Snakes-British-Museum-3/dp/B004II92FO/ref=sr_1_2?s=books&ie=UTF8&qid=1322844318&sr=1-2 Link]</ref> until 1946.<ref name='Günther'>{{cite book |author= [[Albert Günther|Günther, A.]] |title=Report on a Collection of Reptiles and Fishes made by Dr. Kirk in the Zambesi and Nyassa Regions|url=http://archive.org/details/cbarchive_53657_reportonacollectionofreptilesa9999 |volume=1864 |publisher= Proc. Zool. Soc. London| location=London, England |pages=303–314 |year=1864}}</ref> |
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It is one of four species in the African snake genus ''Dendroaspis'' that are known as mambas.<ref name=SpawlsBranch/> |
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==Description== |
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[[File:Dendroaspis polylepis head.jpg|left|thumb|The head and upper part of a relatively young black mamba's body]] |
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The adult black mamba's back skin colour is olive, brownish, gray, or sometimes khaki. A young snake is lighter, but not light enough to be confused with the different species of [[Eastern green mamba|green mamba]]. Its underbody is cream-coloured, sometimes blended with green or yellow.<ref name='Marais'/> Dark spots or blotches may speckle the back half of the body, and some individuals have alternating dark and light scales near the posterior, giving the impression of lateral bars.<ref name=SpawlsBranch/> The inside of the mouth is dark blue to inky black. The head is large but narrow and elongated, with the shape of a coffin.<ref name=ZambiaSnakes/><ref name='Mattison'/> It is a proteroglyphous snake, meaning it has immovable, fixed fangs at the front of the [[maxilla]]. The eyes are dark brown to black, with a silvery-white to yellow edge on the pupils.<ref name='Mattison'>{{cite book|last=Mattison|first=Chris|title=Snakes of the World|publisher=Facts on File, Inc.|date=1987-01-01|location=New York|isbn=0-8160-1082-X|page=164}}</ref> These snakes are strong but slender in body: adult specimens are {{convert|2.5|to|3|m|ft|abbr =on}} in length on average,<ref name='NG'/><ref name='Devenomized'/> but specimens measuring {{convert|3.1|to|3.75|m|ft|abbr =on}} are relatively common, and some specimens have reached lengths of {{convert|4.3|to|4.5|m|ft|abbr =on}}.<ref name='Mattison'/><ref name='Devenomized'>{{cite web|last=Hoser|first=Raymond|title=Captive Care of the Black Mamba (''Dendroaspis polylepis'')|url=http://devenomized.com/libraries/elapids/Black_Mamba.pdf|work=Devenomized|publisher=KingSnake.com|accessdate=2 December 2011}}</ref> The longest scientifically measured, wild-caught black mamba recorded was {{convert|4.48|m|ft}} long, found in [[Zimbabwe]].<ref name=MYTHS>{{cite web|last=Smith|first=Roddy|title=Black Mamba Myths & Other Snake Stories|url=http://www.wildlife-pictures-online.com/black-mamba.html|work=Wildlife Conservation – Lower Zambezi National Park, Zambia|publisher=The Witness|accessdate=2 December 2011}}</ref><ref name='IWE'/> Adult black mambas' slender but powerful body can typically weigh from {{convert|1.6|to|3.1|kg|lb|abbr=on}}.<ref name='NG'/><ref>[http://esapubs.org/archive/ecol/E089/085/appendix-A.htm]</ref> There is no real sexual dimorphism, and both male and female snakes of this species have a similar appearance and tend to be similar in size.<ref name=SUBM/> The species is the second-longest venomous snake in the world, exceeded in length only by the [[king cobra]].<ref name='Mattison'/> Information regarding the lifespan of snakes in the wild is sparse; the longest recorded lifespan of a captive black mamba is 14 years, but actual maximum lifespans could be much greater.<ref name='NG'/><ref name=FitzSimons/> As they age, their colouration tends to get darker.<ref name=SpawlsBranch/> |
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===Scalation=== |
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There are 23–25 rows of smooth dorsal scales at midbody (rarely 21 rows),<ref name='Marais'/><ref name=SpawlsBranch/><ref name=FitzSimons>{{cite book|last=FitzSimons|first=Vivian FM|title=A field guide to the snakes of Southern Africa|year=1970|publisher=HarperCollins|location=Canada|isbn=0-00-212146-8|page=221}}</ref> 248–281 ventrals and 109–132 paired subcaudals. The anal shield is divided. There are 7–10 upper labials, with the fourth (or third and fourth) entering the eye, and 11–13 lower labials (sometimes 10 or 14). There are three (sometimes four) preoculars and three or four (sometimes two or five) postoculars. Temporals are variable, usually 2+3.<ref name=Marais>{{cite book|last=Marais|first=Johan|title=A Complete Guide to the Snakes of Southern Africa|year=2004|publisher=Struik Nature|location=Cape Town, South Africa|isbn=1-86872-932-X|pages=95–97}}</ref> |
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==Distribution, habitat, and status== |
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===Distribution=== |
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Although it is a large [[diurnality|diurnal]] snake, the distribution of the black mamba is the subject of much confusion in research literature, indicating the poor status of African [[herpetology|herpetological]] [[zoogeography]].<ref name='JSTOR'>{{cite journal |title=On the Distribution of the Black Mamba (''Dendroaspis polylepis'') in West Africa |volume=17 |issue=2 |pages=186–187 |year=1983 |journal=Journal of Herpetology |author= Håkansson, Thomas; Madsen, Thomas |doi=10.2307/1563464}}</ref> However, the distribution of the black mamba in [[East Africa|eastern Africa]] and [[southern Africa]] is well documented. [[Charles Pitman (scientist)|Pitman]] (1974) gives the following range for the species' total distribution in Africa: northeastern [[Democratic Republic of the Congo]], southwestern [[Sudan]], [[South Sudan]] to [[Ethiopia]], [[Eritrea]], [[Somalia]], southern [[Kenya]], eastern [[Uganda]], [[Tanzania]], southwards to [[Mozambique]], [[Swaziland]], [[Malawi]], [[Zambia]], [[Zimbabwe]] and [[Botswana]] to [[KwaZulu-Natal]] in [[South Africa]], and into [[Namibia]]; then northeasterly through [[Angola]] to the southeastern part of the Democratic Republic of Congo.<ref name=SUBM>{{cite web|title=Black Mamba Fact File|url=http://www.snakes-uncovered.com/Black_Mamba.html|work=Perry's Bridge Reptile Park|publisher=Snakes-Uncovered|accessdate=2 December 2011}}</ref><ref name='JSTOR'/> According to [[CITES]], the species is also found in [[Lesotho]], [[Rwanda]], and [[Djibouti]].<ref name=CITES>{{cite web|title=Species Database (''Dendroaspis polylepis'')|url=http://www.unep-wcmc-apps.org/isdb/Taxonomy/tax-species-result.cfm?displaylanguage=ENG&Genus=%25dendroaspis%25&source=animals&speciesNo=33987&Country=&tabname=names|work=UNEP-WCMC Species Database|publisher=CITES|accessdate=2 December 2011}}</ref> The black mamba is not commonly found above altitudes of {{convert|1000|m|ft}}, although the distribution of black mamba does reach {{convert|1800|m|ft}} in Kenya and {{convert|1650|m|ft}} in Zambia.<ref name=ZambiaSnakes>{{cite book|last=Broadley; Doria; Wigge|first=DG; CT; J|title=Snakes of Zambia: An Atlas and Field Guide|year=2003|publisher=Edition Chimaira|location=Frankfurt am Main, Germany|isbn=978-3-930612-42-0|page=280}}</ref><ref name='JSTOR'/> The black mamba was recorded in 1954 in West Africa in the [[Dakar]] region of [[Senegal]].<ref name='JSTOR'/> However, this observation, and a subsequent observation that identified a second specimen in the region in 1956, have not been confirmed and thus the species' distribution in [[West Africa]] is inconclusive.<ref name='JSTOR'/> West of Ethiopia, it has a curious distribution, with few records. There is a single record from the [[Central African Republic]], two from [[Burkina Faso]], and as mentioned two unconfirmed sightings from Senegal, one from the [[Gambia]], and a possible sighting in [[Cameroon]]. These sightings may indicate improper documentation, remaining populations from what was once a larger range, or new populations, indicating a growing range.<ref name=SpawlsBranch>{{cite book|last=Spawls|first=Stephen|coauthor=Branch, Bill|title=The dangerous snakes of Africa: natural history, species directory, venoms, and snakebite.|year=1995|publisher=Ralph Curtis-Books|location=Dubai: Oriental Press|isbn=0-88359-029-8|pages=49–51}}</ref> The black mamba's western distribution contains gaps within the [[Central African Republic]], [[Chad]], [[Nigeria]] and [[Mali]]. These gaps may lead physicians to misidentify the black mamba and administer an ineffective antivenom.<ref name='JSTOR'/> |
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===Habitat=== |
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The black mamba has adapted to a variety of climates, ranging from [[savanna]], [[woodland]]s, farmlands, rocky slopes, dense forests and humid [[swamps]].<ref name='JSTOR'/> The [[grassland]] and savanna woodland/shrubs that extend all the way from southern and eastern Africa to central and western Africa, eastern and southern Africa are the black mamba's typical habitat.<ref name='JSTOR'/> The snake prefers more arid environments, such as semiarid, dry bush country, light woodland, and rocky outcrops.<ref name='JSTOR'/><ref name=Pitman74/> This species likes areas with numerous hills, as well as riverine forests. Black mambas often make use of abandoned [[Termite mound#Mounds|termite mounds]] and hollow trees for shelter.<ref name=Pitman74>{{cite book|last=Pitman|first=Charles R.S.|authorlink=Charles Pitman (scientist)|title=A Guide to the Snakes of Uganda|year=1974|publisher=Wheldon & Wesley|location=United Kingdom|isbn=0-85486-020-7|page=290}}</ref> The abandoned termite mounds are especially used when the snake is looking for somewhere to cool off, as the mounds are sort of a "natural air-conditioning" system. The structure of these mounds is very complex and elaborate. They have a network of holes, ducts, and chimneys that allow air to circulate freely, drawing heat away from the nest during the day – though without taking too much valuable moisture – while preventing the nest cooling too much at night.<ref name=SUBM/> As a territorial species, though, the black mamba will always return to its territory or lair if left undisturbed.<ref name=SpawlsBranch/><ref name=Pitman74/> |
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===Conservation status=== |
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This species is classified as [[Least Concern]] (LC) on the [[World Conservation Union|IUCN]] [[IUCN Red List|Red List of Threatened Species]] (v3.1, 2011). The conservation status of this species was last assessed in 2010 and it was classed as such due to its very large distribution throughout [[sub-Saharan Africa]]. Besides its very large geographical distribution, the species has no specific threats or predators that have been reported and this species is not undergoing significant population declines.<ref name='ICUN'>{{Redlist species|no=177584|genus=Dendroaspis|species=polylepis|year assessed=2010|url=http://www.iucnredlist.org/apps/redlist/details/177584/0}}</ref> |
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===Fear, myths, and killings of black mambas=== |
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The black mamba faces human persecution because of its negative reputation throughout [[Africa]]. With the increasing amount of its territory being inhabited by humans, the black mamba often finds itself cornered with no escape. In this situation, it will stand its ground and display fearsome tenacity and explosive aggression while hissing loudly and striking repeatedly. A group of people is usually required to kill it, as it is very fast and agile, striking in all directions while a third of its body is {{convert|3|-|4|ft}} above the ground. The deep fear of this snake stems not only from its reputation for aggression, speed, and venom toxicity, but from stories and legends that have been passed down from generation to generation.<ref name=MYTHS/> |
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==Behaviour and ecology== |
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===Behaviour=== |
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Although its scientific name seems to be indicative of tree climbing, the black mamba is a terrestrial and [[Diurnality|diurnal]] snake.<ref name='Maina'>{{cite journal|pmc=1256818|title=The morphology of the lung of the black mamba Dendroaspis polylepis|last=Maina|first=J.N|date=1989-12|work=The Journal of Anatomy|pmid=2630539|volume=167|journal=J. Anat.|pages=31–46}}</ref> It is known to be capable of reaching speeds of around {{convert|20|km/h|abbr=on}}, travelling with up to a third of its body raised off the ground.<ref name="NG">{{cite web|url=http://animals.nationalgeographic.com/animals/reptiles/black-mamba.html|title=Black mamba|accessdate=2010-03-12|publisher=[[National Geographic Society]]}}</ref> Over long distances, the black mamba can travel {{convert|11|to|19|km/h|abbr =on}}, but it can reach a speed of {{convert|16|to|20|km/h|abbr=on}} in short bursts, and it has been recorded at speeds of {{convert|23|km/h|abbr =on}},<ref name='Adele2'/> making it the fastest land snake in the world.<ref name='Maina'/> The black mamba is a territorial snake, having a favoured home usually in an abandoned termite mound, a hollow tree or log, or a rock crevice. It will actively defend its territory very aggressively.<ref name='Territory'>{{cite book|last=Mitchell|first=Deborah|title=The Encyclopedia of Poisons and Antidotes|publisher=Facts on File, Inc.|date=September 2009|location=New York, USA|page=324|isbn=0-8160-6401-6}}</ref> Although it is a shy and secretive snake in general (often seeking to escape when a confrontation occurs), when cornered, the black mamba can put up a fearsome display of defence and aggression.<ref name='NG'/> When cornered, it mimics a cobra by spreading a neck-flap; exposing its black mouth, it lifts up to a third of its body up off the ground, and hisses.<ref name='NG'/> If the attempt to scare away the attacker fails, it will strike repeatedly.<ref name='NG'/> Many snake experts have cited the black mamba as the world's most aggressive snake, noting tendency to actively attack without provocation.<ref name=Smith05>{{cite book|last=Smith|first=BW|title=Venomous Snakes in Captivity: Safety and Husbandry|year=2005|publisher=Lulu.com|location=United States|isbn=1-4116-2949-3|page=147}}</ref><ref name='Snakes'>{{cite web|last=Haji|first=R.|title=Venomous snakes and snake bite|url=http://www.zoocheck.com/Reportpdfs/Venomous%20snakes.pdf|work=Zoocheck Canada Inc.|accessdate=2 December 2011}}</ref> It can show an incredible amount of tenacity, fearlessness, and aggression when cornered, during breeding season, or when defending its territory.<ref name="ErZug">{{cite book|last= Zug|first= George R.|title= Snakes in Question: The Smithsonian Answer Book |year= 1996|publisher= Smithsonian Institution Scholarly Press |location= Washington D.C., USA|isbn= 1-56098-648-4}}</ref> According to Swaziland-born snake handler and snake expert Thea Litschka-Koen: |
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{{Block quote|"Black mambas will kill a dog or several dogs if threatened and it happens quite often. We also find dead cows and horses! We were called by the frantic family late one evening. When we arrived minutes later, two small dogs had already died and two more were showing severe symptoms of envenomation. Within 15 minutes we had found and bagged the snake. By this time the other two dogs were also dead. The snake must have been moving through the garden when it was attacked by the dogs. It would have struck out defensively, biting all the dogs that came within reach. The snake was bitten in several places on its body as well and died about a week later."''<ref name=Koen>{{cite web|last=Koen|first=Thea Litschka|title=Black Mamba Snake Handler: Thea Litschka-Koen Answers Your Questions|url=http://www.pbs.org/wnet/nature/episodes/black-mamba/snake-handler-thea-litschka-koen-answers-your-questions/5331/|work=PBS Nature|accessdate=13 December 2011}}</ref>}} |
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Similarly, black mambas have been witnessed confronting, biting, and subsequently killing lions and other large predators, such as spotted hyenas and leopards,{{citation needed|date=March 2013}} in defence of their territory, eggs, or when the predators stand between the snakes and their prey.<ref name=Thorpe>{{cite book|last=Thorpe, Wüster, Malhotra|first=Roger S, Wolfgang, Anita|title=Venomous Snakes: Ecology, Evolution, and Snakebite|year=1996|publisher=Oxford University Press, USA|location=US|isbn=0-19-854986-5|page=296}}</ref> |
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===Hunting and prey=== |
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[[File:Dendroaspis polylepis eating.JPG|right|thumb|A black mamba feeding on prey]] |
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When hunting, the black mamba is often seen travelling with its head raised well above ground level, quickly moving forward in search of prey. Once prey is detected, the black mamba "freezes" before hurling itself forward and issuing several quick bites, swiftly killing its prey.<ref name='Adele2'>{{cite book|last=Richardson|first=Adele|title=Mambas|publisher=Capstone Press|year=2004|location=Mankato, Minnesota|page=25| url=http://books.google.com/?id=SMoGSbemC1UC&pg=PA14|accessdate=2010-05-19|isbn=9780736821377}}</ref> If the prey attempts to escape, the black mamba will follow up its initial bite with a series of strikes.<ref name='Adele2'/> It will release larger prey after biting it, but smaller prey, such as birds or rats, are held until the prey's muscles stop moving.<ref name='Adele2'/> Black mambas feed on a variety of prey, especially mammals, including [[hyrax]]es, rats, mice, squirrels, bats, [[bushbabies]] and elephant shrews.<ref name=SpawlsBranch/> They have also been known to prey on birds and small chickens, as well as other snakes, such as the [[Bitis arietans|puff adder]] and [[Cape cobra]].<ref name='IWE'>{{cite book|first=Robert|last=Burton|title=International Wildlife Encyclopedia: Leopard – marten|publisher=Marshall Cavendish|year=2002|location=USA|page=3168|isbn=0-7614-7277-0}}</ref> A large specimen has even been recorded eating a young [[blue duiker]] (''Philantomba monticola'').<ref name=Marais/> After ingestion, powerful acids digest the prey, sometimes within 8 to 10 hours.<ref name='Marais'/> |
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===Communication and perception=== |
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Black mambas show little deviation from the common methods of communication and perception found in snakes. They use their eyesight mainly for detection of motion, and sudden movements will cause them to strike. The tongue is extended from the mouth to collect particles of air, which are then deposited in the vomeronasal organ on the roof of the mouth, which acts as a chemosensory organ. They have no external ears, but are quite adept at detecting vibrations from the ground. Like many snakes, when threatened, they will display aggression with a set of signals warning of the possibility of attack.<ref name='Marais'>{{cite book|last=Marais|first=Johan|title=Snake versus man: A guide to dangerous and common harmless snakes of southern Africa|publisher=Macmillan South Africa|year=1985|location=Braamfontein, Johannesburg (South Africa)|isbn=0-86954-267-2}}</ref> |
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===Reproduction=== |
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[[File:Black mamba, male-male combat.jpg|thumb|right|Males fighting over right to mate]] |
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Black mambas breed only once a year. The breeding season begins in the [[Spring (season)|spring]], which occurs around the month of September in the African regions where these snakes occur, as much of sub-Saharan Africa is in the [[Southern Hemisphere]]. In this period, the males fight over females.<ref name=FitzSimons/> [[Agonistic behaviour]] for black mambas involves wrestling matches in which opponents attempt to pin each other’s head repeatedly to the ground. Fights normally last a few minutes, but can extend to over an hour.<ref name=GreeneFogden>{{cite book|last=Greene; Fogden|first=Harry W.; Michael|title=Snakes: The Evolution of Mystery in Nature|year=2000|publisher=University of California Press|location=United States|isbn=0-520-22487-6|page=351}}</ref> The purpose of fighting is to secure mating rights to receptive females nearby during the breeding season. Beyond mating, males and females do not interact.<ref name=FitzSimons/> Males locate a suitable female by following a scent trail. Upon finding his mate, he will thoroughly inspect her by flicking his forked tongue across her entire body. Males are equipped with two [[hemipenes]].<ref name=SpawlsBranch/> After a successful and prolonged copulation, the eggs develop in the female’s body for about 60 days. During this period, the female seeks a suitable place to lay the eggs. Females prefer using abandoned termite mounds as nests.<ref name=GreeneFogden/> Mature females lay between 15 and 25 eggs, which they hide very well and guard very aggressively. The eggs incubate for about 60 days before hatching. The hatchlings are about {{convert|50|cm|in}} in length and are totally independent after leaving the eggs, hunting and fending for themselves from birth. Young hatchlings are as venomous as the adults, but do not deliver as much venom per bite as an adult snake would. |
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===Natural predators=== |
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[[Mongooses]] and [[predatory birds]] are the main predators of the black mamba.<ref name='Asher'>{{cite journal|pmid=9714553|title=Functional characterization of mongoose nicotinic acetylcholine receptor alpha-subunit: resistance to alpha-bungarotoxin and high sensitivity to acetylcholine|last=Asher|first=O|date=1998-06-04|work=}}</ref> Juvenile mambas are also subject to [[predation]] from [[cape file snake]]s.<ref name='Haagner'>{{cite web|url=http://www3.interscience.wiley.com/journal/119323294/abstract?CRETRY=1&SRETRY=0|title=The maintenance and propagation of the Black mamba Dendroaspis polylepis at the Manyeleti Reptile Centre, Eastern Transvaal|accessdate=2010-05-19|last=Haagner|first=G.V; Dr. Morgan|year=1993|format=PDF|work=International Zoo Yearbook|publisher=Zoological Society of London}}</ref> |
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==Venom== |
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[[File:Dendroaspis polylepis striking.JPG|left|thumb|upright=0.86|A black mamba striking]] |
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Among mambas, toxicity of individual specimens within the same species and subspecies can vary greatly based on several factors, including geographical region (there can be great variation in toxicity from one town or village to another).<ref name="ErZug"/> Its venom is the most rapid-acting venom of any snake species<ref name=Chippaux/>{{clarify|date=November 2012}} and consists mainly of highly potent [[neurotoxin]]s;<ref name=WCH/><ref>Reed, Tim; Eaton, Katie; Peng, Cathy and Doern, BettyLou. [http://cogs.csustan.edu/~tom/bioinfo/groupwork/cobra/cobra-venom.ppt Neurotoxins in Snake Venom]. California State University Stanislaus. csustan.edu. Retrieved on 2012-07-08.</ref> it also contains [[cardiotoxin]]s,<ref name='Territory'/><ref name=MambaCDTX>{{cite journal |title=Putative cardiotoxicity of the venoms of three mamba species |journal=Journal of Wilderness and Environmental Medicine |volume=7|issue=2 |year= 1996 |pmid=11990104 |pages=115–21 |author=van Aswegen G, van Rooyen JM, Fourie C, Oberholzer G.}}</ref> fasciculins,<ref name=WCH/> and [[calciseptine]].<ref name='Calciseptine'/> [[Subcutis|Subcutaneous]] {{LD50}} values for this species' venom varies greatly. Australian toxic database provides values of 0.32 mg/kg for [[subcutaneous injection]], 0.25 mg/kg for [[intravenous injection]] and 0.941 mg/kg for [[intraperitoneal injection]].<ref name= "LD50">{{cite web|url=http://www.seanthomas.net/oldsite/ld50tot.html|title=LD50 |author= Thomas, Séan and Griessel, Eugene |date=December 1999}}</ref><ref name=Engelmann>{{cite book|last=Engelmann|first=Wolf-Eberhard|title=Snakes: Biology, Behavior, and Relationship to Man|year=1981|publisher=Leipzig Publishing; English version published by Exeter Books (1982)|location=Leipzig; English version NY, USA|isbn=0-89673-110-3|page=53}}</ref> Ernst and Zug ''et al.'' 1996 gave it a value of 0.05 mg/kg,<ref name="ErZug"/> Spawls and Branch list it as 0.28 mg/kg,<ref name=SpawlsBranch/> and Brown gave it a value of 0.12 mg/kg.<ref name=Brown73>{{cite book|last=Brown|first=JH|title=Toxicology and Pharmacology of Venoms from Poisonous Snakes.|year=1973|publisher=Charles C. Thomas|location=Springfield, Illinois|isbn=0-398-02808-7|lccn=73–229|page=184}}</ref> |
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It is estimated that only 10 to 15 mg will kill a human adult, and its bites delivers about 50–120 mg of venom on average.<ref name= "LD50"/><ref name=SpawlsBranch/> The largest envenomation on record is 400 mg.<ref name=Chippaux>{{cite book|last=Chippaux|first=Jean-phillipe|title=Snake Venoms and Envenomations|year=2006|publisher=Krieger Publishing Company|location=United States|isbn=1-57524-272-9|page=300}}</ref> Its bite is often called "the kiss of death" because, before [[antivenom]] was widely available, the mortality rate from a bite was 100% since this species always delivers fatal dosage of venom during every envenomation.<ref name=Oshea05/><ref name='Territory'/><ref name='Davidson'/> Severe black mamba envenomation can kill a person in 30 minutes,<ref name='Davidson'/> but sometimes it takes up to 2–3 [[hour]]s,<ref name=ZambiaSnakes/><ref name='Davidson'/> depending upon many factors.<ref name='Davidson'/> The fatality <!-- duration and --> rate depends on various factors, such as the health, size, age, and psychological state of the victim, the penetration of one or both fangs from the snake, the amount of venom injected, the [[pharmacokinetics]] of the venom, the location of the bite, and its proximity to major blood vessels.<ref name="NG"/> The health of the snake and the interval since it last used its venom mechanism is important, as well. Currently, a polyvalent [[antivenom]] produced by the South African Institute for Medical Research (SAIMR) is used to treat all black mamba bites from different localities.<ref name=SpawlsBranch/><ref name='Davidson'/> Due to antivenom, a bite from a black mamba is no longer a certain death sentence. But in order for the antivenom to be successful, vigorous antivenom therapy must be administered very rapidly post-envenomation. The doses of antivenom required are often massive (10–12 vials). Cases where 100 cm<sup>3</sup> of antivenom is required are not at all unusual.<ref name=SpawlsBranch/><ref name='Davidson'/> |
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If bitten, severe neurotoxicity often ensues.<ref name='Davidson'/> [[Neurology|Neurological]], [[Respiratory system|respiratory]], and [[cardiovascular]] symptoms rapidly begin to manifest, usually within ten minutes or less. Common symptoms are rapid onset of dizziness, drowsiness, coughing or difficulty breathing, convulsions, and an erratic heartbeat.<ref name='Davidson'/> Other common symptoms which come on rapidly include neuromuscular symptoms, shock, loss of consciousness, [[hypotension]], [[pallor]], [[ataxia]], excessive salivation (oral secretions may become profuse and thick), limb paralysis, nausea and vomiting, [[Ptosis (eyelid)|ptosis]], fever, and very severe abdominal pain. Local tissue damage appears to be relatively infrequent and of minor severity in most cases of black mamba envenomation. [[Edema]] is typically minimal.<ref name='Davidson'/> A black mamba can rear up around one-third of its body from the ground, which can put it at about four feet high. When warding off a threat, the black mamba delivers multiple strikes, injecting large amounts of virulently toxic venom with each strike, often landing bites on the body or head, unlike other snakes.<ref name=Chippaux/> The venom of this species has been known to cause permanent [[paralysis]] if treatment with antivenom was delayed.<ref name='Davidson'/> Death is due to suffocation resulting from paralysis of the respiratory muscles.<ref name='Davidson'>{{cite web|url=http://drdavidson.ucsd.edu/portals/0/snake/dendroa3.htm|title=Immediate First Aid|accessdate=2010-05-12|last=Davidson|first=Terence|publisher=University of California, San Diego}}</ref> |
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Because of various factors, including the toxicity and high venom yield, the fact that untreated bites have a mortality rate of 100%, as well as aggressiveness, speed, agility, and size of black mamba, it is considered one of the world's deadliest and most aggressive snake species.<ref name=SnakeGuide>{{cite web|title=Guide: Common Snakes "Dangerous"|url=http://www.hikinginfo.co.za/DOCS/Snake%20Guide.pdf|publisher=South African Government|accessdate=21 March 2013}}</ref><ref name='Daniel'>{{cite journal|url=http://www.jbc.org/content/247/12/4029.full.pdf+html|title=Snake Venom Toxins|last=Strydom|first=Daniel|year=1972|journal=The Journal of Biological Chemistry|volume=247|pages=4029–4042}}</ref> Herpetologists who share this view include [[Wolfgang Wüster]], [[Charles Pitman (scientist)|Charles Pitman]], Johan Marais, Vivian FitzSimons, Ray Hunter, and [[Austin Stevens]].<ref name=Pitman74/> Nevertheless, attacks on humans are relatively rare, as the snakes usually avoid confrontation with humans and their occurrence in highly populated areas is not as common as some other African species of venomous snakes.<ref name=Oshea05/> |
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===Toxins=== |
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Mamba venom is made up mostly of [[dendrotoxin]]s (dendrotoxin-k – "Toxin K",<ref name="ReferenceA">{{cite journal|title=[Nuclear magnetic resonance solution structure of dendrotoxin K from the venom of Dendroaspis polylepis polylepis.] |volume=234 |issue=3 |pages= 735–50|year=1993 |pmid=8254670 |journal=Journal of Molecular Biology |doi=10.1006/jmbi.1993.1623 |author=Berndt KD, Güntert P, Wüthrich K.}}</ref> dendrotoxin-1 – "Toxin 1",<ref name="ReferenceB">{{cite journal|title=[Potassium channels and epilepsy: evidence that the epileptogenic toxin, dendrotoxin, binds to potassium channel proteins.] |volume=4 |pages=263–73|year=1991 |pmid=1815606 |journal=Epilepsy Research Supplement |author=Newitt RA, Houamed KM, Rehm H, Tempel BL.}}</ref> dendrotoxin-3 – "Toxin 3",<ref name=Rang>{{cite book |author=Rang, H. P. |title=Pharmacology |publisher=Churchill Livingstone |location=Edinburgh |year=2003 |page= 139 |isbn=0-443-07145-4}}</ref> dendrotoxin-7 – "Toxin 7",<ref name=Rang/> among others), fasciculins, and [[calciseptine]].<ref name='Calciseptine'>{{cite journal|title=Calciseptine, a peptide isolated from black mamba venom, is a specific blocker of the L-type calcium channel|url= http://www.ncbi.nlm.nih.gov/pmc/articles/PMC51247/|volume=88 |issue=6 |pages=2437–2440.|date=15 March 1991 |pmc= 51247|journal=Proceedings of the National Academy of Science of the United States of America |pmid=1848702 |author=J R de Weille, H Schweitz, P Maes, A Tartar, and M Lazdunski|doi=10.1073/pnas.88.6.2437}}</ref> Being a protein of low [[Molecular mass|molecular weight]], the venom and its constituents are able to spread extraordinarily rapidly within the bitten tissue, so black mamba venom is the most rapid-acting of all snake venoms.<ref name=Chippaux/> The dendrotoxins disrupt the exogenous process of [[muscle contraction]] by means of the [[sodium potassium pump]]. Toxin K is a selective blocker of voltage-gated potassium channels,<ref name="ReferenceA"/> Toxin 1 inhibits the K<sup>+</sup> channels at the pre and postsynaptic level in the intestinal smooth muscle. It inhibits Ca<sup>2+</sup>-sensitive K<sup>+</sup> channels from rat skeletal muscle‚ incorporated into planar bilayers (Kd = 90 nM in 50 mM KCl),<ref name="ReferenceB"/> Toxin 3 inhibits [[M4 receptors]], while Toxin 7 inhibits [[M1 receptors]].<ref name=Rang/> The calciseptine is a 60 amino acid peptide which acts as a smooth muscle relaxant and an inhibitor of cardiac contractions. It blocks K<sup>+</sup>-induced contraction in aortic smooth muscle and spontaneous contraction of uterine muscle and portal vein.<ref name='Calciseptine'/> The venom is highly specific and virulently toxic. In one experiment, the death time of a mouse after subcutaneous injection of some toxins studied, was around seven minutes. However, black mamba venom can kill a mouse after 4.5 minutes.<ref name='Daniel'/> |
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Black mamba venom also contains proteins, [[mambalgins]], which in [[House mouse#Laboratory mice|mice]] act as an [[analgesic]] as strong as [[morphine]], but without most of the [[side-effect]]s. Mambalgins cause much less tolerance than morphine and no respiratory distress.<ref name=NaturePh>{{cite doi|10.1038/nature11494|noedit}}</ref> They act through a completely different route, [[acid-sensing ion channel]]s. Laboratory tests suggest that the pain-killing effect on humans may be similar, but this had not been tested {{As of|2012|10|lc=on}}. Researchers were puzzled about the advantage this substance could give the snakes.<ref name=NaturePh /><ref>{{cite web|url=http://www.bbc.co.uk/news/health-19812064 |title=Black mamba venom is 'better painkiller' than morphine|publisher=BBC|date=3 October 2012|accessdate=3 October 2012|first=James |last=Gallagher|work=BBC News Health}} Describes research by Dr Eric Lingueglia and others, [[Institute of Molecular and Cellular Pharmacology]] (Institut de Pharmacologie Moléculaire et Cellulaire), France</ref> |
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===Situation in Africa=== |
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Venomous snakebites are rampant in sub-Saharan Africa.<ref name=IST>{{cite web|last=Kasturiratne|first=A|title=Global Snakebite Statistics – Epidemiology|url=http://www.toxinology.org/GSI-epidemiology2.htm|work=International Society on Toxinology – Global Snakebite Initiative|publisher=International Society on Toxinology (IST)|accessdate=13 December 2011}}</ref> Although antivenom is now widely available and bite victims can rapidly access adequate treatment in most of Africa's medium to large cities and nearby areas,<ref name='Davidson'/> some severely impoverished African nations do not always have antivenom in stock, as it is very expensive, even by Western standards.<ref name=AntivenomSwazi/> One example is [[Swaziland]], where the black mamba mortality rate is still very close to 100% because of the lack of antivenom and proper care methods (i.e. mechanical ventilation equipment, proper envenomation symptom control, lack of drugs, etc.). However, Swaziland does have "Antivenom Swazi", which is a charity whose mission is to raise enough funds to create a "bank" of antivenom for treating [[snakebite]]s, but they are specifically focused on treating black mamba bite victims in Swaziland.<ref name=AntivenomSwazi>{{cite web|title=Antivenom Swazi Foundation|url=http://www.antivenomswazi.org/#|work=Antivenom Swazi Trust Fund|publisher=www.antivenomswazi.org|accessdate=9 December 2011}}</ref> Another problem common to most African nations where black mambas occur is that bite victims in rural and isolated areas cannot access treatment and therefore have no chance to survive. Pockets of areas with a 100% mortality rate due to black mamba envenomation still exist in Africa.<ref name=Zimbabwe>{{cite journal|last=Nhachi|first=Charles FB|coauthors=Kasilo, Ossy M|title=Snake poisoning in rural Zimbabwe—A prospective study|journal=Journal of Applied Toxicology|year=1994|volume=14|issue=3|pages=191–193|doi=10.1002/jat.2550140308|pmid=8083480}}</ref> However, bites attributed to this species are far less likely compared to most African cobra species and to the puff adder. In Tanzania, while the black mamba is second to the [[Bitis arietans|puff adder]] in causing human fatalities, the puff adder bites almost six times the number of people that the black mamba does.<ref name='Marais'/><ref name=IST/> A survey of snakebites in South Africa from 1957 to 1963 recorded over 900 venomous snakebites, but only seven of these were confirmed black mamba bites. From the 900 bites, only 21 ended in fatalities, including all seven black mamba bites – a 100% mortality rate.<ref name=Oshea05>{{cite book|last=O'Shea|first=Mark|title=Venomous Snakes of the World|year=2005|publisher=New Holland Publishers|location=United Kingdom|isbn=0-691-12436-1|page=78|quote=...in common with other snakes they prefer to avoid contact;...from 1957 to 1963...including all seven black mamba bites - a 100 per cent fatality rate}}</ref> This and many other studies which found a 100% fatality rate among black mamba bites stimulated the production of a specific mamba antivenom, and in 1967 Louw reported the first successful treatment of two black mamba bites with a specific antivenom prepared by the [[South African Institute of Medical Research]]. This was the first time that any victim of a black mamba bite was documented to survive envenomation.<ref name=SpawlsBranch/> |
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==References== |
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{{Reflist|colwidth=30em}} |
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==External links== |
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{{Wikispecies|Dendroaspis polylepis}} |
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*{{Commons category-inline|Dendroaspis polylepis}} |
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*[http://www.venomousreptiles.org/articles/336 Venomous Reptiles – Black mamba] |
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*[http://www.blueplanetbiomes.org/black_mamba.htm Blue Planet Biomes Black Mamba article] |
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[[Category:Animals described in 1864]] |
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[[Category:Elapidae]] |
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[[Category:Elapidae by common name]] |
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[[Category:Reptiles of Africa]] |
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[[Category:Snakes]] |
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[[Category:Snakes of Africa]] |
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[[Category:Venomous snakes]] |
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Revision as of 15:22, 2 October 2013
a very large, black weiner