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==Behaviour==
==Behaviour==
[[Image:Dendroaspis polylepis (14).jpg|left|thumb|160px]]
[[Image:Dendroaspis polylepis (14).jpg|left|thumb|160px]]
The black mamba is a [[Diurnality|diurnal]] snake. Although its scientific name seems to be indicative of tree climbing, itthe black mamba is rarely an [[arboreal]] 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> The black mamba is known to be capable of reaching speeds of around {{convert|20|km/h|sp=us}}, traveling 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|sp=us}}, but in short bursts it can reach a speed of {{convert|16|to|20|km/h|sp=us}}, and it's even been recorded at speeds of {{convert|23|km/h|sp=us}},<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, a hollow log, or a rock crevice. It will actively defend its territory very aggressively.<ref name='Territory'>{{cite book|last=Turkington|first=Carol|last=Mitchell|first=Deborah|title=The Encyclopedia of Poisons and Antidotes|publisher=Facts on File, Inc.|date=September 2009|location=New York, USA|pages=324|isbn=0816064016}}</ref> Although it is a shy and secretive snake in general; it always seeks to escape when a confrontation occurs, unless cornered in which case the black mamba can put up a fearsome display of defense 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, the black mamba 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='Snakes'/> Herpetologist Dr. Ray Hunter has also claimed that the black mamba is both the deadliest and most aggressive venomous snake he has ever had to deal with. Dr. Hunter said that dealing with an angry black mamba "is like dealing with the devil himself, the sound of the hissing, the repeated striking, and the way they rush at you even when you let them go is something I have never seen any cobra, not even the king cobra, or any other snake for that matter do. No snake behaves that way or to that degree".<ref name=Hunter>{{cite web|last=Hunter|first=Ray|title=HUNTER SERPENTOLOGY|url=http://www.cobraman.net/4436.html|publisher=Cobraman.net|accessdate=7 December 2011}}</ref><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=1411629493|pages=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> They can show an incredible amount of tenacity, fearlessness, and aggression when they are cornered, during breeding season, or when defending its territory.<ref name='Snakes'/><ref name="ErZug"/>
The black mamba is a [[Diurnality|diurnal]] snake. Although its scientific name seems to be indicative of tree climbing, the black mamba is rarely an [[arboreal]] 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> The black mamba is known to be capable of reaching speeds of around {{convert|20|km/h|sp=us}}, traveling 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|sp=us}}, but in short bursts it can reach a speed of {{convert|16|to|20|km/h|sp=us}}, and it's even been recorded at speeds of {{convert|23|km/h|sp=us}},<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, a hollow log, or a rock crevice. It will actively defend its territory very aggressively.<ref name='Territory'>{{cite book|last=Turkington|first=Carol|last=Mitchell|first=Deborah|title=The Encyclopedia of Poisons and Antidotes|publisher=Facts on File, Inc.|date=September 2009|location=New York, USA|pages=324|isbn=0816064016}}</ref> Although it is a shy and secretive snake in general; it always seeks to escape when a confrontation occurs, unless cornered in which case the black mamba can put up a fearsome display of defense 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, the black mamba 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='Snakes'/> Herpetologist Dr. Ray Hunter has also claimed that the black mamba is both the deadliest and most aggressive venomous snake he has ever had to deal with. Dr. Hunter said that dealing with an angry black mamba "is like dealing with the devil himself, the sound of the hissing, the repeated striking, and the way they rush at you even when you let them go is something I have never seen any cobra, not even the king cobra, or any other snake for that matter do. No snake behaves that way or to that degree".<ref name=Hunter>{{cite web|last=Hunter|first=Ray|title=HUNTER SERPENTOLOGY|url=http://www.cobraman.net/4436.html|publisher=Cobraman.net|accessdate=7 December 2011}}</ref><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=1411629493|pages=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> They can show an incredible amount of tenacity, fearlessness, and aggression when they are cornered, during breeding season, or when defending its territory.<ref name='Snakes'/><ref name="ErZug"/>


===Hunting and prey===
===Hunting and prey===

Revision as of 14:24, 13 December 2011

For other uses, see Black mamba (disambiguation).

Black mamba
A black mamba in defense mode
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Subphylum:
Vertebrata
Class:
Reptilia
Order:
Squamata
Suborder:
Serpentes
Family:
Elapidae
Genus:
Dendroaspis
Species:
D. polylepis
Binomial name
Dendroaspis polylepis
Range of the black mamba

The black mamba (Dendroaspis polylepis), also called the common black mamba or black-mouthed mamba,[4] is the longest venomous snake in Africa, averaging around 2.5 to 3.2 meters (8.2 to 10.5 ft) in length, and sometimes growing to lengths of 4.45 meters (14.6 ft).[5] Its name is derived from the black colouration inside the mouth rather than the actual colour of its scales which varies from dull yellowish-green to a gun-metal grey. It is 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).[1] It's also a very "notorious" snake that's feared throughout the world and it generally has a very bad reputation for being very aggressive, explosive, and highly venomous, and many snake experts have cited this species as both the world's deadliest and most aggressive species, noting tendency to actively attack without provocation.[6][7] One expert even calls this species "death incarnate".[8] They are among the world's ten most venomous land snakes in the world,[9] and when threatened or cornered they often become very explosive[7] and fiercely aggressive, which is why they are given mythical status and many myths, legends, and stories about this species abound.[10]

Taxonomy

The black mamba was first described in 1864 by Albert Günther, a German-born British zoologist, ichthyologist, and herpetologist. Soon after, the species was found to have a subspecies Dendroaspis polylepis antinorii (Peters, 1873), but this is no longer accepted as a separate subspecies.[2][3] However, in 1896 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[11] until 1946, when Dr. Vivian FitzSimons split them into separate species again.[12][13]

Etymology

The snake's scientific name is Dendroaspis polylepis: Dendroaspis meaning "tree asp" (dendro is "tree", while aspis is "asp" which is understood to mean a "venomous snake") and polylepis derives from the Greek term which means "many scaled." poly (or polu) means "many" and lepis means "scales".[14][15] 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.[1] It displays this physical attribute when threatened.[1]

Description

The head and upper part of a relatively young black mamba's body.

The adult black mamba's back skin colour is olive, brownish, gray, or sometimes khaki in colour. Young snakes are lighter in colour, appearing gray or olive green, but are not light enough to be confused with the different species of green mamba. Their underbody is cream-coloured, sometimes blended with green or yellow.[5] 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.[16] The inside of the mouth is a dark blue to "inky" black in colour. The head is big but narrow and elongated, with a distinct shape of a "coffin".[17][18] It is a proteroglyphous snake, meaning it has non-movable, 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.[18] These snakes are strong but slender in body, adult specimens are 2.5 to 3 meters (8.2 to 9.8 ft) in length on average,[1][19] but specimens measuring 3.1 to 3.75 meters (10.2 to 12.3 ft) are relatively common, and some specimens have reached lengths of 4.3 to 4.5 meters (14 to 15 ft).[18][19] Africans and wild game hunters have claimed to have seen black mamba specimens measuring 5 to 6.5 meters (16 to 21 ft) in length, but of course none of these are confirmed or verified by scientists using scientific methods. The longest scientifically measured wild caught black mamba on record was a specimen which was found in Zimbabwe and was 4.48 metres (14.7 ft) long and weighed 11.7 kilograms (26 lb).[20][21] Black mambas weigh about 5.6 kilograms (12 lb) on average, though they can weigh up to 12.5 kilograms (28 lb).[1][22] 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.[23] The species is the second longest venomous snake in the world, exceeded in length only by the king cobra.[18] The snake has an average life span of 11 years in the wild.[1] As they age, their colouration tends to get darker.[16][24] Their smooth scales are at mid-body, in 23 to 25 (in some cases 21) rows.[16][5][25]

Range, habitat, and status

Range

Although a large, diurnal, and "notorious" snake, the distribution of the black mamba is the subject of much confusion in research literature, indicating the poor status of African herpetological zoogeography.[26] However, the distribution of the black mamba in eastern Africa and southern Africa is well documented. 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, Kenya, eastern Uganda, Tanzania, southwards to Mozambique, Swaziland, Malawi, Zambia, Zimbabwe and Botswana to KwaZulu-Natal in South Africa, and Namibia; then northeasterly through Angola to the southeastern part of the Democratic Republic of Congo.[23] [26] According to CITES, the species is also found in Lesotho, Rwanda, and Djibouti.[27] The black mamba is not commonly found above altitudes of 1,000 metres (3,300 ft), although the distribution of black mamba does reach 1,800 metres (5,900 ft) in Kenya and 1,650 metres (5,410 ft) in Zambia.[17][26] The black mamba was also recorded in 1954 in West Africa in the Dakar region of Senegal.[26] 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.[26] 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.[16][26]

Habitat

The black mamba has adapted to a variety of climates ranging from savanna, woodlands, farmlands, rocky slopes, dense forests and even humid swamps.[26] 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.[26] The black mamba prefers more arid environments such as semi-arid dry bush country, light woodland, and rocky outcrops.[26][28] This species likes areas with a lot of hills as well as riverine forests. Black mamba's also often make use of abandoned termite mounds and hollow trees for shelter.[28] 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.[23] However, as a territorial species the black mamba will always return to their territory.[16][28]

Conservation status

This species is classified as Least Concern (LC) on the IUCN Red List of Threatened Species (v3.1, 2001). 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 it's 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.[29]

Environmental encroachment

The sugarcane fields that dominate the habitat of the black mamba.

Although the black mamba is not an endangered or threatened species by any means, its environment is rapidly diminishing in many parts of its range in Africa. In Swaziland alone, 75% of the population is employed by subsistence farming.[30] Because of agricultural encroachment on the black mamba's habitat, the snake is commonly found in sugarcane fields. The black mamba will climb to the top of the sugarcane to bask in the sun and possibly wait for prey. The majority of human attacks occur in the sugarcane fields of east and southern Africa in which are employed thousands of workers for manual labour, as cane growing is not a highly mechanised industry. This encroachment on the snake's territory contributes to potentially dangerous human contact with these highly venomous snakes.[1] Similar encroachment is also being seen in Kenya, where the black mamba's is a very common species. In Kenya, there is immense pressure on the water resources from agricultural chemicals and urban and industrial wastes, as well as from use for hydroelectrical power.[31] Resource degradation has caused the output of forestry to decline. Overexploitation over the past three decades has reduced the country’s timber resources by one-half. At present, only 2% of the land remains forested, and an estimated 50 square kilometres (19 square miles) of forest are lost each year. This loss of forest aggravates erosion, the silting of dams and flooding, and the loss of biodiversity. There are a wide variety of wildlife species in Kenya, whose habitats are threatened by the encroachment of man, this includes the black mamba and even the Eastern green mamba, which is highly arboreal.[31][32] Deforestation and encroachment on its territory is occurring throughout much of its range in Africa as many of the African countries want to further develop their nations and that is not only putting pressure on the species but it contributes to more potentially dangerous human contact with these snakes. It is entirely possible that bites and deaths attributed to black mamba's will rise in the next decade.[1] Although antivenom is available, some African countries do not always have it in stock. One example is Swaziland, where the black mamba mortality rate is still about 100% because of the lack of antivenom and proper care methods (ie. 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 black mamba bite victims in Swaziland.[24] The only victims that do survive are the ones who are lucky enough to be bitten when black mamba antivenom is in stock and is quickly administered within the first 15-30 minutes, as antivenom administered beyond 30 minutes post-envenomation will usually keep the victim alive but depending on the nature of the bite, permanent paralysis from the shoulder down may occur if the bite was serious in nature or if the bite wasn't as serious as black mamba bites usually are, then the victim would make a full recovery without any problems. In very severe cases of envenomation, the victim may not live longer than 30 minutes, as the neurotoxins (dendrotoxins) of the black mamba are the most rapid-acting snake venom known.[33] So it is crucial for antivenom to be administered rapidly.[34][24]

Fear, myths, and killings of black mambas

File:D-polylepis close up.jpg
A close up of a black mamba

Another problem which this species faces is human persecution as it is feared throughout the continent of Africa. Although it would much rather avoid confrontation and flee from any perceived threat, the black mamba can be extremely aggressive if badgered long and hard enough, during breeding season, when defending territory or an egg nest, or if cornered with no escape, it will stand its ground and display fearsome tenacity and explosive aggression while hissing loudly and striking repeatedly.[7] No other snake in the continent is as loathed, and yet respected and feared at the same time. For this reason, many black mamba's are killed right where they are spotted by villagers.[10][20] It usually requires a group of people to kill it as it is very fast and agile, striking in all directions while a third of its body is 3–4 feet above the ground. Villagers will use rocks, big knives, saws, or big pieces of wood to either chop the snake, crush it, or kill it in some fashion. The black mamba will sometimes bite one or two of the villagers before being killed itself.[24] This is common in some parts of its geographical range. The deep fear of this snake stems not only from its reputation for aggression, speed, and venom toxicity, but it also stems from stories and legends that have been passed down from one generation to the next.[20] It's claimed that the mere mention of its name can cause fear, anxiety, or panic attacks in some people. The indigenous Africans that share stories of how this snake has been seen chasing away herds of Cape buffalos, wildebeests, and even chasing away humans. Magical abilities have even been attributed to it, which has added to the myth, mystery, and fear of the black mamba. Other stories include black mamba's biting and killing full grown bull elephants, which are unverified. However, there is a scientifically verified record of a fully grown adult female elephant that died due to black mamba envenomation in 2006.[35] Many other legendary stories have been attributed to this species, most are myths, some are unconfirmed and only a very few of them are said to be "possible" based upon what we know of this species' behavior.[10]

Behaviour

The black mamba is a diurnal snake. Although its scientific name seems to be indicative of tree climbing, the black mamba is rarely an arboreal snake.[36] The black mamba is known to be capable of reaching speeds of around 20 kilometers per hour (12 mph), traveling with up to a third of its body raised off the ground.[1] Over long distances the black mamba can travel 11 to 19 kilometers per hour (6.8 to 11.8 mph), but in short bursts it can reach a speed of 16 to 20 kilometers per hour (9.9 to 12.4 mph), and it's even been recorded at speeds of 23 kilometers per hour (14 mph),[37] making it the fastest land snake in the world.[36] The black mamba is a territorial snake, having a favoured home usually in an abandoned termite mound, a hollow tree, a hollow log, or a rock crevice. It will actively defend its territory very aggressively.[38] Although it is a shy and secretive snake in general; it always seeks to escape when a confrontation occurs, unless cornered in which case the black mamba can put up a fearsome display of defense and aggression.[1] 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.[1] If the attempt to scare away the attacker fails, the black mamba will strike repeatedly.[1] Many snake experts have cited the black mamba as the world's most aggressive snake, noting tendency to actively attack without provocation.[6] Herpetologist Dr. Ray Hunter has also claimed that the black mamba is both the deadliest and most aggressive venomous snake he has ever had to deal with. Dr. Hunter said that dealing with an angry black mamba "is like dealing with the devil himself, the sound of the hissing, the repeated striking, and the way they rush at you even when you let them go is something I have never seen any cobra, not even the king cobra, or any other snake for that matter do. No snake behaves that way or to that degree".[39][40][6] They can show an incredible amount of tenacity, fearlessness, and aggression when they are cornered, during breeding season, or when defending its territory.[6][9]

Hunting and prey

As stated, the black mamba is a diurnal species. When hunting, it actively seeks prey and 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.[37] If the prey attempts to escape, the black mamba will follow up its initial bite with a series of strikes.[37] The black mamba will release larger prey after biting it, but smaller prey, such as birds or rats, are held onto until the prey's muscles stop moving.[37] The black mamba feeds almost solely on warm-blooded animals, such as birds and small mammals including hyraxes and various rodents. They have even been known to prey on bushbabies, bats, and small chickens[12] as well as other snakes like the puff adder and Cape cobra.[21] After ingestion, powerful acids digest the prey, sometimes within 8 to 10 hours.[5]

Communication and perception

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.[5]

Predators

The Martial Eagle is a predator of young or small black mambas.

The black mamba has no real natural predators, but humans and birds of prey are its main threat.[12][22] Very large specimens of this species (10 feet and up) have only humans to fear as even many birds of prey won't go after such specimens, preferring smaller sized snakes.[22] The Egyptian mongoose, which shares much of its geographical range with all species of mambas, has shown a particularly high level of resistance to three species of venomous snake: the Palestine viper, Desert black snake, and the black necked spitting cobra, and also all Naja (cobra) species in general.[41] This resistance is caused by mutations in their nicotinic acetylcholine receptor, but resistance to dendrotoxins, which are the main components of the black mamba's venom, is not seen. In fact, dendrotoxin's have been shown to bind to the alpha subunits of mongoose species, unlike cobratoxins.[42] Most species of mongoose in Africa (and elsewhere for that matter) show a very strong resistance to α-cobratoxin. The mongoose's α-subunits don't bind the toxin and thus most species of mongoose are able to survive bites from both the true cobra's (genus Naja) and also the king cobra, which isn't a "true" cobra but shares the same cobratoxins of the true cobras.[42] However, mongoose do on occasion prey on very young snakes and black mamba eggs. Mongooses, especially the yellow mongoose attack only young snakes as they are very small and thus can be killed with ease, while large black mambas usually fight back, are very quick, and can deliver a lethal bite. Cape file snakes have also been observed preying on young black mambas, but this is uncommon.[12]

Reproduction

The breeding season for black mambas begins in the 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. Agonistic behaviour for black mambas involves wrestling matches in which opponents attempt to pin each other’s head repeatedly to the ground.[7] Fights normally last a few minutes but can extend to over an hour or more.[7] The purpose of fighting is to secure mating rights to receptive females nearby during the breeding season. Mating begins with the male inspecting the female with his forked tongue. After a successful copulation the eggs develop in the female’s body for about 60 days. During this period, the female goes and seeks a suitable place in which to lay her eggs in. Females prefer using abandoned termite mounds as nests, but a warm and slightly damp hole, hollow tree, or even decaying vegetation will do if a termite mound isn't available.[7] 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 50 centimetres (20 in) in length and are totally independent after leaving the eggs, hunting and fending for themselves right from birth. Young hatchlings are just as venomous as the adults, but don't deliver as much venom per bite as an adult snake would. Still, new born hatchlings have been known to hunt, kill, and eat rats. They've also caused mortality in adult humans.[5][24]

Venom

File:Mouth-dpolylepis.jpg
The black mamba with its mouth opened wide, displaying the inky-black colouration of the inside of its mouth.

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) and even weather.[9] Being a protein of low molecular weight, the venom of the black mamba is the most rapid-acting venom of any snake species[33][43] and consists mainly of potent neurotoxins,[4][44] it also contains cardiotoxins,[38][45][46] fasciculins,[4] and calciseptine.[47] Subcutaneous LD50 values for this species' venom varies greatly. Ernst and Zug et al. 1996 gave it a value of 0.05 mg/kg,[9] Dr. Bryan Grieg Fry of the University of Queensland gave it a value of 0.32 mg/kg,[48] and Brown gave it a value of 0.12 mg/kg.[33] Although there's great variation, the average SC value of the black mamba's venom is said to be around 0.185 mg/kg, making it one of the most venomous land snakes in the world.[9][33][49][34][50] To illustrate just how toxic the venom of this species is, in 2006, a fully grown adult female elephant named Eleanor, who was a matriarch of an entire herd and was between 40 and 48 years of age[51] and weighed over 7,500 pounds, was bitten and subsequently killed by a black mamba at Samburu National Reserve in Kenya.[35] Scientists in the field shot footage of Eleanor's herd calling out in distress and making desperate attempts to get the dying elephant back onto her feet, but Eleanor succumbed to the venom and died. To date, this is the only known case in which a snake bit and killed an adult elephant.[35]

Although only 10 to 15 mg[46][52] is deadly to a human adult, its bite delivers about 100–120 mg of venom on average,[46][52] but they can deliver up to over 400 mg of venom in a single bite.[52][43] Its bite is often called "the kiss of death"[53] because before antivenom was widely available, the mortality rate from a bite was 100%.[1][38][34][1][49][53][54] Severe black mamba envenomation can potentially kill a human within 20 minutes or less[1][33][52][55] depending on the nature of the bite and the area bitten, but death usually occurs after 30–60 minutes on average, sometimes even taking up to three hours.[17][33] British wildlife enthusiast Nathan Layton was bitten in Hoedspruit, a small city near Kruger National Park, by a juvenile black mamba and died in less than 30 minutes after being bitten. Nearby ambulance personnel were called to the scene, but Mr. Layton was already dead by the time they had arrived.[56] The fatality duration and rate depend on various factors, such as the health, size, age, psychological state of the human, the penetration of one or both fangs from the snake, amount of venom injected, location of the bite, and proximity to major blood vessels.[1] The health of the snake and the interval since it last used its venom mechanism is also important. Presently, there is a polyvalent antivenom produced by the South African Institute for Medical Research (SAIMR) to treat all black mamba bites from different localities.[16][34]

If bitten, neurological, respiratory, and cardiovascular symptoms rapidly begin to manifest, usually within five minutes or less.[33] Common symptoms for which to watch are rapid onset of dizziness, drowsiness, coughing or difficulty breathing, convulsions, and an erratic heartbeat.[34] 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, 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.[34] In cases where the victim has received larger amounts of venom than average (over 200 mg +) or the venom was delivered right into a vein, death can result within as little as 10 minutes[1][55] from respiratory or cardiac arrest.[34] This is also true if the victim is bitten in the face or chest area, as 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.[43] The venom of this species has also been known to cause permanent paralysis if treatment with antivenom was delayed.[34] Death is due to suffocation resulting from paralysis of the respiratory muscles.[34]

Due to various factors including the toxicity and high yield of its venom, the fact that untreated bites have a mortality rate of 100%, its high level of aggression, its speed, agility, and size, many herpetologists[6] tend to agree to the notion that the black mamba is the deadliest and most aggressive snake species in the world.[6][55][57] Herpetologist's who share this view include world renowned Wolfgang Wüster, Charles Pitman, Ray Hunter, Stephen Spawls, and even Austin Stevens.[16][28] Stevens has mentioned this several times on different episodes of his hit TV series Austin Stevens: Snakemaster. Nevertheless, attacks on humans by black mambas are relatively rare, as the snakes usually avoid confrontation with humans and their occurrence in highly-populated areas is not as common compared to many other African species of venomous snakes.

Toxins

Mamba venom is made up mostly of dendrotoxins (dendrotoxin-k - "Toxin K",[58] dendrotoxin-1 - "Toxin 1",[59] dendrotoxin-3 - "Toxin 3",[60] dendrotoxin-7 - "Toxin 7",[60] among others), fasciculins, and calciseptine.[47] Being a protein of low molecular weight, the venom and its constituents are able to spread extraordinarily rapidly within the bitten tissue and as a result black mamba venom is the most rapid-acting of all snake venoms.[33][43] 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,[58] Toxin 1 inhibits the K+ channels at the pre and post-synaptic level in the intestinal smooth muscle. It also inhibits Ca2+-sensitive K+ channels from rat skeletal muscle‚ incorporated into planar bilayers (Kd = 90 nM in 50 mM KCl),[59] Toxin 3 inhibits M4 receptors, while Toxin 7 inhibits M1 receptors.[60] The calciseptine is a 60 amino acid peptide which acts as a smooth muscle relaxant and an inhibitor of cardiac contractions. It blocks K+ induced contraction in aortic smooth muscle and it blocks spontaneous contraction of uterine muscle and portal vein.[52][47] 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 7 minutes. However, black mamba venom can kill a mouse after 4.5 minutes.[55]

Situation in Africa

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,[34] some severely impoverished African nations do not always have antivenom in stock as it is very expensive, even by Western standards.[61][30] 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 (ie. 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 snakebites, but they are especially focused on treating black mamba bite victims in Swaziland.[61] Another problem common to most African nations where black mambas occur is the fact that bite victims in rural and isolated areas cannot access treatment and therefore don't stand a chance. Pockets of areas with a 100% mortality rate due to black mamba envenomation still exist in Africa.[62] However, bites attributed to this species are far less likely compared to most African cobra species and the puff adder. In Tanzania, the black mamba is second only to the puff adder in causing human fatalities, but the puff adder bites more than 15 times the amount of people that the black mamba does.[5] Other snakes in Tanzania which are responsible for far more bites than the black mamba include the Egyptian cobra (N. haje), Black forest cobra (N. melanoleuca), Red spitting cobra (N. pallida), and the Mozambique spitting cobra (N. mossambica), yet still fatalities due to black mamba bites are more numerous.[24][63]

Gallery

  • Black mamba at Wilmington's Serpentarium
    Black mamba at Wilmington's Serpentarium
  • A black mamba climbing a branch at the London zoo
    A black mamba climbing a branch at the London zoo
  • A coiled up black mamba
    A coiled up black mamba
  • A close up of the black mamba's "coffin" shaped head
    A close up of the black mamba's "coffin" shaped head
  • A black mamba at the St. Louis zoo
    A black mamba at the St. Louis zoo
  • A stretched out black mamba
    A stretched out black mamba
  • A black mamba with lighter colouration and shiny scales
    A black mamba with lighter colouration and shiny scales
  • Large and darker coloured black mamba
    Large and darker coloured black mamba
  • A black mamba looking right at the camera
    A black mamba looking right at the camera
  • A black mamba looking forward
    A black mamba looking forward
  • Black mamba opening its mouth wide
    Black mamba opening its mouth wide

References

  1. ^ a b c d e f g h i j k l m n o p q r "Black mamba". National Geographic Society. Retrieved 2010-03-12.
  2. ^ a b "Dendroaspis polylepis". Integrated Taxonomic Information System. Retrieved 2 December 2011.
  3. ^ a b Uetz, Peter. "Dendroaspis polylepis GÜNTHER, 1864". Reptile Database. Zoological Museum Hamburg. Retrieved 2 December 2011.
  4. ^ a b c "Dendroaspis polylepis - General Details, Taxonomy and Biology, Venom, Clinical Effects, Treatment, First Aid, Antivenoms". WCH Clinical Toxinology Resource. University of Adelaide. Retrieved 2 December 2011.
  5. ^ a b c d e f g Marais, Johan (1985). Snake versus man: A guide to dangerous and common harmless snakes of southern Africa. Braamfontein, Johannesburg (South Africa): Macmillan South Africa. ISBN 0869542672.
  6. ^ a b c d e f Haji, R. "Venomous snakes and snake bite" (PDF). Zoocheck Canada Inc. Retrieved 2 December 2011.
  7. ^ a b c d e f Greene; Fogden, Harry W.; Michael (2000). Snakes: The Evolution of Mystery in Nature. United States: University of California Press. p. 351. ISBN 0520224876.{{cite book}}: CS1 maint: multiple names: authors list (link)
  8. ^ Lee, Douglas. "Black mamba! Meet the African species that one expert calls 'death incarnate.'". International Wildlife. National Wildlife Federation. Retrieved 2 December 2011.
  9. ^ a b c d e Zug, George R. (1996). Snakes in Question: The Smithsonian Answer Book. Washington D.C., USA: Smithsonian Institution Scholarly Press. ISBN 1560986484.
  10. ^ a b c Smith, Roddy. "Black Mamba Myths & Other Snake Stories". Wildlife Conservation - Lower Zambezi National Park, Zambia. The Witness. Retrieved 2 December 2011.
  11. ^ Boulenger, G.A. 1896. Catalogue of the Snakes in the British Museum (Natural History), Volume III. ASIN: B004II92FO. London. p. 437. Link
  12. ^ a b c d Haagner, G.V; Dr. Morgan (1993). "The maintenance and propagation of the Black mamba Dendroaspis polylepis at the Manyeleti Reptile Centre, Eastern Transvaal" (PDF). International Zoo Yearbook. Zoological Society of London. Retrieved 2010-05-19.{{cite web}}: CS1 maint: multiple names: authors list (link)
  13. ^ Günther, A. (1864). Report on a Collection of Reptiles and Fishes made by Dr. Kirk in the Zambesi and Nyassa Regions. Vol. 1864. London, England: Proc. Zool. Soc. London. pp. 303–314.
  14. ^ Rauchenberger, Mary (18). "A New Species of Allodontichthys (Cyprinodontiformes: Goodeidae), with Comparative Morphometrics for the Genus". Copeia - American Society of Ichthyologists and Herpetologists. 2: 433–441. doi:10.2307/1445884. Retrieved 2 December 2011. {{cite journal}}: Check date values in: |date= and |year= / |date= mismatch (help); Unknown parameter |month= ignored (help)
  15. ^ Hardy Fern Library - polylepis etymology
  16. ^ a b c d e f g Spawls, Stephen (1995). The dangerous snakes of Africa: natural history, species directory, venoms, and snakebite. Dubai: Oriental Press: Ralph Curtis-Books. p. 192. ISBN 0883590298. {{cite book}}: Unknown parameter |co-author= ignored (help)
  17. ^ a b c Broadley; Doria; Wigge, DG; CT; J (2003). Snakes of Zambia: An Atlas and Field Guide. Frankfurt am Main, Germany: Edition Chimaira. p. 280. ISBN 978-3-930612-42-0.{{cite book}}: CS1 maint: multiple names: authors list (link)
  18. ^ a b c d Mattison, Chris (1987-01-01). Snakes of the World. New York: Facts on File, Inc. p. 164. ISBN 081601082X.
  19. ^ a b Hoser, Raymond. "Captive Care of the Black Mamba (Dendroaspis polylepis)" (PDF). Devenomized. KingSnake.com. Retrieved 2 December 2011.
  20. ^ a b c "Black Mamba Facts". Siyabona Africa (Pty) Ltd - The Definitive Kruger Park Guide. http://www.krugerpark.co.za. Retrieved 2 December 2011. {{cite web}}: External link in |publisher= (help)
  21. ^ a b Burton, Robert (2002). International Wildlife Encyclopedia: Leopard - marten. USA: Marshall Cavendish. p. 3168. ISBN 0761472770.
  22. ^ a b c Hallowell, Edward (7). Proceedings of the National Academy of Sciences (Stanford University's Highwire Press). 2 (3): 57–62. doi:10.2307/4058479 http://pubget.com/paper/pgtmp_jstor4058479. Retrieved 2 December 2011. {{cite journal}}: Check date values in: |date= and |year= / |date= mismatch (help); Missing or empty |title= (help); Unknown parameter |month= ignored (help)
  23. ^ a b c "Black Mamba Fact File". Perry's Bridge Reptile Park. Snakes-Uncovered. Retrieved 2 December 2011.
  24. ^ a b c d e f "Black Mamba". BBC Knowledge. British Broadcasting Corporation. Retrieved 2 December 2011.
  25. ^ FitzSimons, Vivian FM (1970). A field guide to the snakes of Southern Africa. Canada: HarperCollins. p. 221. ISBN 0002121468.
  26. ^ a b c d e f g h i "On the Distribution of the Black Mamba (Dendroaspis polylepis) in West Africa". Journal of Herpetology. 17 (2): 186–187. 1983. {{cite journal}}: Cite uses deprecated parameter |authors= (help); Unknown parameter |month= ignored (help)
  27. ^ "Species Database (Dendroaspis polylepis)". UNEP-WCMC Species Database. CITES. Retrieved 2 December 2011.
  28. ^ a b c d Pitman, Charles R.S. (1974). A Guide to the Snakes of Uganda. United Kingdom: Wheldon & Wesley. p. 290. ISBN 0854860207. {{cite book}}: Check |first= value (help)
  29. ^ Dendroaspis polylepis at the IUCN Red List
  30. ^ a b "UNDP: Human development indices – Table 3: Human and income poverty (Population living below national poverty line (2000-2007))" (PDF). United Nations Development Programme. 28 November 2008. Retrieved 29 December 2009.
  31. ^ a b "Environmenal issues in Kenya". Provincial Environmental Committees (PECS) and District Environment Committees (DECS). National Environment Management Authority (NEMA). Retrieved 7 December 2011.
  32. ^ Otieno, Jeff. "Vegetation loss threatens to push wildlife species into extinction". Daily Nation. Retrieved 7 December 2011.
  33. ^ a b c d e f g h Brown, JH (1973). Toxicology and Pharmacology of Venoms from Poisonous Snakes. Springfield, Illinois: Charles C. Thomas. p. 184. ISBN 0-398-02808-7. {{cite book}}: Unknown parameter |lcccn= ignored (help)
  34. ^ a b c d e f g h i j Davidson, Terence. "IMMEDIATE FIRST AID". University of California, San Diego. Retrieved 2010-05-12.
  35. ^ a b c Sheldrick, Daphne. "Elephants with broken hearts". Daily Mail Online. Retrieved 2 December 2011.
  36. ^ a b Maina, J.N (1989-12). "The morphology of the lung of the black mamba Dendroaspis polylepis". J. Anat. 167: 31–46. PMC 1256818. PMID 2630539. {{cite journal}}: Check date values in: |date= (help); More than one of |work= and |journal= specified (help)
  37. ^ a b c d Richardson, Adele (2004). Mambas. Mankato, Minnesota: Capstone Press. p. 25. Retrieved 2010-05-19.
  38. ^ a b c Mitchell, Deborah (September 2009). The Encyclopedia of Poisons and Antidotes. New York, USA: Facts on File, Inc. p. 324. ISBN 0816064016.
  39. ^ Hunter, Ray. "HUNTER SERPENTOLOGY". Cobraman.net. Retrieved 7 December 2011.
  40. ^ Smith, BW (2005). Venomous Snakes in Captivity: Safety and Husbandry. United States: Lulu.com. p. 147. ISBN 1411629493.
  41. ^ Ovadia, M. and Kochva. E. (1977) Neutralization of Viperide and Elapidae snake venoms by sera of different animals. Toxicon 15. 541-547
  42. ^ a b Conti-Tronconi BM, Raftery MA. (1986). "Nicotinic acetylcholine receptor contains multiple binding sites: evidence from binding of alpha-dendrotoxin". Proc. Natl. Acad. Sci. U.S.A. 83 (17): 6646–50. PMC 386561. PMID 3462717. {{cite journal}}: Unknown parameter |month= ignored (help)
  43. ^ a b c d Chippaux, Jean-phillipe (2006). Snake Venoms and Envenomations. United States: Krieger Publishing Company. p. 300. ISBN 1575242729.
  44. ^ [cogs.csustan.edu/~tom/bioinfo/groupwork/cobra/cobra-venom.ppt Neurotoxins in Snake Venom]
  45. ^ "Putative cardiotoxicity of the venoms of three mamba species". Journal of Wilderness and Environmental Medicine. 7 (2): 115–21. May 1996. PMID 11990104. {{cite journal}}: Cite uses deprecated parameter |authors= (help)
  46. ^ a b c Gilbert, Steven. "Black mamba (Dendroaspis polylepis)". Toxipedia. Toxipedia.org. Retrieved 7 December 2011.
  47. ^ a b c "[Calciseptine, a peptide isolated from black mamba venom, is a specific blocker of the L-type calcium channel.]". Proceedings of the National Academy of Science of the United States of America. 88 (6): 2437–2440. 15 March. PMC 51247. PMID 1848702. {{cite journal}}: Check date values in: |date= and |year= / |date= mismatch (help); Cite uses deprecated parameter |authors= (help)
  48. ^ Fry, Bryan Grieg. "Subcutaneous LD50 values". Australian Venom Research Unit. University of Queensland. Retrieved 25 November 2011.
  49. ^ a b Thomas, Sean. "LD50". www.seanthomas.net. www.seanthomas.net/oldsite/. Retrieved 7 December 2011.
  50. ^ "LD50 Menu". Retrieved 2010-04-21.
  51. ^ "Life of Eleanor the Elephant". Orphan's Project. The David Sheldrick Wildlife Trust. Retrieved 7 December 2011.
  52. ^ a b c d e "Black Mamba Biology". Retrieved 2011-09-13.
  53. ^ a b Lee, Donald. "THIRTEEN's Nature goes to Swaziland to track Africa's deadliest snake in Black Mamba" (PDF). Nature - PBS. www.pbs.org. Retrieved 7 December 2011.
  54. ^ "Black Mamba - Introduction". PBS - Nature. www.pbs.org. Retrieved 7 December 2011.
  55. ^ a b c d Strydom, Daniel (1971-11-12). "Snake Venom Toxins" (PDF). The Journal of Biological Chemistry. Retrieved 2010-04-24.
  56. ^ Fernandez, Colin. "British wildlife student dies in front of girlfriend minutes after being bitten by black mamba snake". Daily Mail Online. Retrieved 7 December 2011.
  57. ^ "Deadliest Snakes in the World". Manbir-Online for Health & Fitness. www.manbir-online.com. Retrieved 7 December 2011.
  58. ^ a b "[Nuclear magnetic resonance solution structure of dendrotoxin K from the venom of Dendroaspis polylepis polylepis.]". Journal of Molecular Biology. 234 (3): 735–50. 1993. doi:10.1006/jmbi.1993.1623. PMID 8254670. {{cite journal}}: Cite uses deprecated parameter |authors= (help); Unknown parameter |month= ignored (help)
  59. ^ a b "[Potassium channels and epilepsy: evidence that the epileptogenic toxin, dendrotoxin, binds to potassium channel proteins.]". Epilepsy Research Supplement. 4: 263–73. 1991. PMID 1815606. {{cite journal}}: Cite uses deprecated parameter |authors= (help)
  60. ^ a b c Rang, H. P. (2003). Pharamacology. Edinburgh: Churchill Livingstone. p. 139. ISBN 0-443-07145-4.
  61. ^ a b "Antivenom Swazi Foundation". Antivenom Swazi Trust Fund. www.antivenomswazi.org. Retrieved 9 December 2011.
  62. ^ Nhachi, Charles FB (1994). "Snake poisoning in rural Zimbabwe—A prospective study". Journal of Applied Toxicology. 14 (3): 191–193. doi:10.1002/jat.2550140308. PMID 8083480. Retrieved 9 December 2011. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)
  63. ^ Spawls, Howell, Drewes, Stephen, Kim, Robert (2006). Pocket Guide to the Reptiles and Amphibians of East Africa. United Kingdom: Christopher Helm Publishers Ltd. p. 240. ISBN 0713674253.{{cite book}}: CS1 maint: multiple names: authors list (link)

External links

Media related to Dendroaspis polylepis at Wikimedia Commons

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