Black mamba
| Black mamba | |
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| Species: | D. polylepsis
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| Binomial name | |
| Dendroaspis polylepsis | |
The black mamba (Dendroaspis polylepis) is the longest venomous snake in Africa, averaging around 8 feet (2.5 m), but sometimes growing up to 14 feet (4.3 m). Its name is due to the black inside of its mouth; the actual color of the skin varies, from dull yellowish-green to a gun-metal grey. It is one of the fastest snakes in the world, capable of moving at 10 to 12 mph (16 to 20 km/h).[1]
Etymology
The snake's scientific name is Dendroaspis polylepis. Dendroaspis means "tree snake." Polylepis means "many scaled."
The name "black mamba" is given to the snake not because of its body color but because of its ink-black mouth.[1]
Description
Ironically, The Black Mamba's skin color can be olive, brownish, gray, or sometimes khaki in color. The younger Black Mambas are lighter, appearing gray or olive green. The Black Mamba’s belly is cream-colored, sometimes blended with green or yellow. The Black Mamba also appears to have lateral bars running down its body. This effect is from dark spots or blotches that speckle the back half of the body and alternating dark and light scales near the posterior. Their smooth scales are at mid-body, in 23 to 25 rows. The eyes are dark brown to black, with a silvery-white to yellow edge on the pupils. The adult Black Mamba's length ranges from 2.0 to 3.0 m, with an average length of 2.2 to 2.7m long [8 feet].[2] There have been rare cases of Black Mambas reaching lengths of 4.3 and even 4.5m long [14 feet][3]
Distribution and habitat
The Black Mamba lives in Africa. Its distribution ranges from Eritrea in the north-east, through to South Africa, and as far west as Namibia. This includes Swaziland, Mozambique, Zimbabwe, Zambia, Botswana, Ethiopia, Kenya, Uganda, Angola, Malawi, and the Congo.[4] The Black Mamba thrives in the hot and humid environment of the region. It lives in rocky hills, riverine forest with downed trees providing shelter, and wooded-savannah. Because of agricultural encroachment on the Black Mamba's habitat, the snake is commonly found in sugarcane fields. Rodents and amphibians also live in the sugarcane. 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, as thousands of workers must plow the fields by hand. The Black Mamba's most active hunting month is in October because of the warm spring climates.[3]
Behaviour
The Black Mamba prefers traveling on ground, but some are arboreal.[3] They are shy, secretive and will normally retreat from danger. However, this snake will become highly aggressive if it feels threatened, especially if the threat is standing between the snake and its lair. They use their incredible speed to escape threats, not to hunt prey.[5] When in its aggressive mode, the Mamba will rear its head as high as possible, even sometimes being able to look directly into the eyes of an averaged sized human depending on the snake's size. It will arch its back and advance rapidly while balanced on the rear third of its body, jaws open to reveal the inky black inside of its mouth while hissing loudly. It maintains a home range, but is not considered highly territorial.
When hunting small animals it delivers a single bite and backs off, waiting for the neurotoxin in its venom to paralyze the prey. If the prey is a bird, it will usually hang on to the bird waiting for the venom to take effect (lest it fly away and die where the snake cannot find it), the limited supply of venom being diminished without helping the snake survive. If fighting off a threat, it will deliver multiple deadly strikes.
Reproduction
Spring is the Black Mamba’s mating season. This occurs around September in the African regions. Males will attempt to locate a female by following her scent trail. Once a female is found, the male inspects the female’s body with its tongue. The male Black Mamba is equipped with a dual set of penises (hemipenes). If mating is successful the female will lay up to 17 eggs in a nest underground or in a hallow tree. The eggs hatch in about 3 months, during the summer season. During mating season, males will engage in combat. The males fight by coiling around each other; this is often mistaken for mating. The winner will attempt to pin the loser's head to the ground.[3]
Venom
The venom of the Black Mamba is mainly neurotoxin, with a LD50 of 0.25 mg/kg. Its bites deliver about 100–120 mg of venom on average, however it can deliver up to 400 mg; 10 to 15 mg is deadly to a human. One snake can produce enough venom to kill 15-25 people. Mortality rate is nearly 100% unless the snakebite victim is promptly treated with antivenom or is put on a respirator or ventilator. There is a polyvalent antivenom produced by SAMIR (South African Institute of Medical Research) to treat all Black Mamba bites from different localities.[1][6]
The venom is potent, and due to its aggressive nature and its speed, it is widely regarded as one of the most dangerous snakes in Africa. However, bites from Black Mambas to humans are rare, as the snakes would rather avoid confrontation with humans.[1][5] If bitten, common symptoms to watch for are rapid onset of dizziness, coughing or difficulty breathing, and erratic heart-beat. In extreme cases, when the victim has received a large amount of venom, death can result within an hour from respiratory or cardiac arrest. Also, the Black Mamba's venom has been known to cause paralysis.[7] Black Mamba bites can potentially kill a human within 20 minutes depending on the health, size, age, and psychological state of the human; but death usually occurs after 30–60 minutes, sometimes taking up to three hours. Death is due to suffocation resulting from paralysis of the muscles used for breathing. Other factors include penetration of one or both fangs, amount of venom injected, location of the bite, and proximity to major blood vessels. The health of the snake and the interval since it last used its venom mechanism is also important.
References
- ^ a b c d "Richard Mastenbrok's Elapid Pages".
- ^ Smith, Roddy. "Black Mamba Myths and Other Snake Stories". Wildlife Pictures Online. Retrieved 2010-03-04.
- ^ a b c d Scott, Randy. "Dendroaspis polylepis". University of Michigan Museum of Zoology Animal Diversity Web. Retrieved 2010-02-28. Cite error: The named reference "Randy" was defined multiple times with different content (see the help page).
- ^ Litschka-Koen, Thea (2009-11-09). "Snake Handler Thea Litschka-Koen Answers Your Questions". Nature. PBS. Retrieved 2010-02-28.
- ^ a b "Black Mamba". National Geographic Society. Retrieved 2010-03-12.
- ^ "LD50 menu". Retrieved 2010-03-13.
{{cite news}}: Cite has empty unknown parameter:|coauthors=(help) - ^ Thomas, Sean (1999-12-10). "Most Dangerous Snakes in the World". Seanthomas.net. Retrieved 2010-03-13.
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Gallery
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Black mamba at Wilmington's Serpentarium. -
Close-up of a Black mamba's head -
Close-up of the snake climbing a branch, in London Zoo. -
A Black Mamba at the St Louis zoo.
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