Dendroaspis polylepis

Family : Elapidae

Text © Dr. Gianni Olivo

 

English translation by Mario Beltramini

 

The Black mamba (Dendroaspis polylepis Günther, 1864, family Elapidae) whose scientific name means small scaled serpent of the trees is the typical example of zoological name which may create confusion. Actually, the colour of this serpent is never black, as it varies from the grey to the green-grey, the brown and to (especially in old individuals) to the gun-metal, often with slight and thin askew bands on the distal part of the body and on the tail, but the name of “black” is due to the colour of the oral mucosa the reptilian uses as intimidation when opening the mouth.

Dendroaspis (tree asp) is the name defining the genus and forms the first part of the scientific name, common to all the four species known as mamba, but, whilst the other three species of green mambas are strictly arboreal, deserving one hundred per cent such adjective, the black mamba is mainly terrestrial, even if it may easily climb and it spends part of the time on trees and shrubs, for hunting nestlers or squirrels as well as for escaping from a danger or, especially when the soil is wet, like after heavy rains, for avoiding its excessive humidity.

The head is unmistakable, elongated and slightly compressed on the sides, shaped like a coffin (symbolism not completely far away from the truth), the mouth is ample and the labial commissure, with superior concavity, gets well behind the eye, which is of medium size and with round pupil. The poison fangs are shorter than those of the viperids even if of much smaller size, and in any case do not reach the centimetre (as an average, 5-7 mm), but are indeed terribly efficacious weapons. The body, thin if compared to its length, has small and smooth scales which confer it a sericeous appearance and, at half length, are placed in a number of rows from 21 to 25 (most often 23-25).

The mambas are elapids, they are therefore proteroglyphous poison serpents which, unlike the viperids (more evolved), do not have poison fangs foldable on the palate; but fixed and placed on the fore part of the superior maxilla. However, in the case of the mambas, the grooved fangs are provided of certain mobility and the squared bone may rotate forward, thus rendering the bite even more effectual.

This is the longest poisonous serpent after the Asiatic King cobra: the new born measure already 50 or 60 cm, and are perfectly able to inoculate an amount of venom several times superior than the minimum necessary to kill an adult man; the reptilian reaches almost the two metres during its first year of life and then grows up more slowly. An adult specimen has an average length from 220 to 300 cm, but it may be 450 cm long; 3 m long individuals are not rare. Many texts aver that the black mamba prefers open zones of dry savannah at low altitude, but indeed, it happened to me to sight one at more than 2.000 m in Tanzania and in my area, it is common over the 1.500 m.

On the contrary, in our location, very green and rich of thick bush, often covered by lichens and interrupted by rocks and crevices which, together with the termite mounds, offer abundance of shelters, the black mamba appears to be the most common venomous serpent, followed immediately by the Mozambique spitting cobra (Naja mossambica) which often shares the same shelters. Sedentary animal with fixed habits, it loves staying in the sun, always in a certain place and uses the same shelter, if not disturbed, for years.

It is a day hunter, very active and it doesn’t hunt by ambush; it doesn’t hesitate in climbing even high trees, looking for nestlers and rodents. It catches also mammals as big as the hyrax and they have even reported one case of predation on a blue duiker.

Many legends have flourished about its velocity: obviously, many assertions are exaggerated, like the one which alleges that it may overtake a running horse; in any case, top speeds of 15 km/h are credible and it is in any case matter of a remarkable speed and of an impressive view due to the deadly grace with which it seems to fly on the uneven ground, disappearing and appearing again between grass and bush.

I have seen, many times, mambas which, at the moment of taking shelter on a plant, raise at the last moment, but still in full movement, the fore half of the body without any effort. The nimbleness of these animals is unbelievable and they are capable to hit with precision even if moving at full speed and even laterally, as I saw once, at the expense of an unlucky dog and there are reports of a pack of six dogs all killed by the same mamba as they had had the very bad idea to attack it.

When moving on the ground, the Dendroaspis polylepis keeps the head well raised from the soil and in this manner it is in condition to locate the prey or a possible danger and react as required. The black mamba is the most feared among the African and world serpents, for the power of its venom, neurotoxic, and for the enormous quantities of the same it can inoculate with a single bite, as well as for its speed and nimbleness, which allow the animal to bite a person on the face, the superior limbs or the thorax. Furthermore, unlike what happens with other poisonous serpents which often bite without inoculating poison (dry bites), the black mamba almost always inoculates a full amount of it and often bites repeatedly, so much that, before the advent of the polyvalent or specific serum, the bite was fatal practically in 100% of instances.

Another reason of its sinister reputation is its extreme hastiness which renders it unforeseeable and aggressive, aggressiveness which increases during the reproduction period. On the other hand, luckily, the cases of bite are less frequent than with the other serpents, just because it is an extremely active, fast and nervous serpent, which means that it tends to get away when it perceives the vibrations caused by an approaching intruder. However it happens, unluckily, that at times the animal realizes at the last moment the presence of a human, and, if it feels menaced or trapped, it often attacks, biting repeatedly and with the speed of a lightning. Some of the most dangerous situations do happen when a mamba chooses as habitual haven a tool shed, a generator shed or another space of human living quarters: the entrance of a person in such case will trigger a swift reaction. Once I was called by my tracker because a mamba had chosen as dwelling an old obsolete water discharge, just in front of the kitchen of my house, and I was able to drive it out and seize it with a pliers for snakes only by widening the drain, otherwise, the presence of this guest would have revealed as very much dangerous. In another instance, a specimen entered our bath creating a very dangerous situation, especially if I had not timely noticed its presence.

While walking in the bush, this reptilian goes unnoticed the most of times, because it gets away at the least sign of human approach and hardly may it be approached at less than 20 m, but there are cases where the accident happens anyway, as it occurred to me close to my house, a few years ago. Another highly risky situation takes place when a mamba, forced out by our arrival, has climbed a bush or has reached the low branches of a plant: while walking in the bush it is easy in this way to get close to the serpent with the face, and it will react, being already alarmed and annoyed, by biting. For this reason, when I am taking people in the bush, I always recommend to look alternatively at the ground where they put their feet and at the branches of the bushes where they pass through. In case of a close encounter, however, the serpent does not always bite without warning; at times, before, it assumes a typical menacing position, with the fore part of the body raised from the ground, often at a remarkable height, it wide opens the mouth exhibiting the black mucosa, while the tongue is rapidly darting, often accompanying the warning with a low angry hiss and widening a long “hood”, much narrower than that of the cobras. At this point, if the foe does not get away slowly or does not keep still, the reaction is fast and violent and consists in a series of quick bites; each one of them may inject from 100 to 400 mg of poison which is fatal for an adult man in the quantity of 12-15 mg.

If we keep perfectly still, usually the reptilian will low down the fore part of the body and will go away. The only African elapid provided of a neurotoxic venom of a power similar to the black mamba, is the Cape cobra (Naja nivea), whilst other species of cobras have poisons which, even if fatal, are so in higher doses.

This poison has the texture of a thick liquid, similar to the glycerine, clear and, once dried up, is of white colour (whilst that, for instance, of the cobras, is yellow).

The action of the dendrotoxin is mainly neurotoxic and operates inhibiting the transmission at synaptic level, that is, in the point where the nerve terminal interfaces with the muscular fibre, with consequent progressive paralysis of muscular groups culminating in the paresis of the respiratory ones and subsequent death by choking if an efficacious intervention does not take place. At the level of the endplate, the arrival of the neural impulse frees substances called neurotransmitters (i.e. acetylcholine), which pass through the synapse and carry the order of contraction to the muscular fibres.

The neurotoxic venoms may operate in different levels and in different ways: some interrupt the process upstream (pre-synaptic action), blocking the release of the transmitter (i.e. the bungarotoxin of the kraits of Asia), some, on the contrary, operate downstream (post-synaptic block) and act in way that the neurotransmitter cannot go to fix (taipoxin of Australia and Papua-New Guinea taipans), but the dendrotoxin of the mambas operates in an even different way, blocking the nodes of Ranvier of the motoneurons and consequently those called “sodium channels”, thus increasing and inhibiting the efficacy of the acetylcholine and causing, with a mechanism almost opposite to the previous ones, a prolonged excitability of the muscular fibres with symptoms even convulsive; the final outcome, will be, in any case, an inefficiency of the muscles and subsequent choking. Indeed, there are different dendrotoxins: in the black mamba, the most studied are the dendrotoxin I and the dendrotoxin K, whilst the Eastern green mamba (Dendroaspis angusticeps ) has an alpha-dendrotoxin, besides beta, gamma and delta-dendrotoxins; the Western green mamba (Dendroaspsis viridis) of western Africa has a DV14-dendrotoxin. An odd particular: it has been discovered that some sea anemones such as Anemonia sulcata have toxins called Kalicludins with a structure similar to the dendrotoxins. Those of the black mamba appear to be the most powerful among all the others.

However, the venoms of the mambas contain also some cardiotoxins which seem to operate directly on the heart, in this case, however, the cardiotoxin of the black mamba (which has a venom much more powerful than the green mambas) is less powerful than that of the arboreal relatives among which stands first the Jameson’s green mamba (Dendroaspis jamesoni) of central Africa, followed by the Dendroaspis angusticeps and then by Dendroaspis polylepis.  Concluding, then, the bite of the black mamba is fatal mainly for respiratory paralysis but usually the first symptoms are concern the facial muscles, as the cranial nerves are the most sensitive and subject to the action of the neurotoxic poisons. In case of bite, then, it may be useful, while waiting for help, the artificial respiration, to be affected till when rescuers arrive, keeping pervious the respiratory tract. Finally, here are a few oddities concerning the most known and feared among the African serpents.

Indlondlo is the name that the AmaZulu give to a legendary crested mamba, but this legend has a background of reality as, at times, very old mambas, by the time of changing the skin keep, for some time, flaps of the old skin on the skull, thus simulating a sort of a crest. Furthermore, some populations call indlondlo also the horned viper (Bitis caudalis) whilst the Amatabele call indlondlo various serpents among which the harmless Spotted bush snake (Philotamnus semivariegatus). For various ethnic groups, moreover, in the mamba do reincarnate the spirits of the ancestors and these serpents are called abathakati, word indicating also some types of wizards.

Common names. English: Black mamba; afrikaans: Swart mamba; isiZulu, shangane and ndebele: Imamba elimnyama; xhosa: Mamba emnyama; shona: Hangara; tswana and northern sotho: Mokopa; venda: Kangala.

 

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