Some South African Snakes

I

THE indigenous fauna of South Africa was, a century ago, richer in genera and species than that in any other part of the globe. To-day the mammals have largely disappeared, — ruthlessly obliterated, — mostly slain by natives armed with the white man’s weapons. Even fifty years since, vast tracts were still stocked with noble wild beasts, whose numbers and variety are quite incredible except to the old wanderers whose feet, in those long-bygone days, trod those then remote wildernesses. The reptiles were, relatively, almost as numerous as the mammalia, but their habits have enabled them to avoid destruction to the same extent. Usually dwelling underground, and largely of nocturnal habit, the lizard and the snake still survive in considerable numbers, except in the immediate vicinity of the abodes of men.

Yet one may live to-day in an environment in which are large numbers of snakes, and be hardly aware of their existence unless some unusual conditions bring them to one’s notice. Before entering the Indian Ocean the Great Fish River runs for some hundreds of miles through a deep valley, between high banks of clay heavily perforated by the burrows of large fieldmice and other rodents. Its sluggish, muddy current is usually of insignificant volume. But occasionally heavy up-country rains cause the river to swell into a brimming torrent, on which are borne quantities of uprooted trees and shrubs. The mouse-holes become submerged and the snakes (principally the great African viper, Bitis arrietans, known as the ‘puff adder’), which share the burrows apparently on amicable terms with the rodents, emerge to avoid being drowned. Gripped by the flood, they climb into the branches of the drifting trees and are swept out to sea. Soon afterwards the trees are cast ashore by the tide, their occupants chilled and lifeless. But on the first hot day they come to life and may be seen basking on the sand in quite embarrassing numbers. Then one realises that there are still snakes, and plenty of them, in South Africa.

The classification of snakes is as yet indecisive; its terms frequently change; in each system hitherto proposed numerous anomalies may be pointed out. One principle has, however, been established, namely, that no solid-toothed snake is venomous, but all snakes possessing grooved, channeled, or tubular fangs are venomous in a greater or less degree. No snake masticates its food. The teeth are invariably sharp and recurved, and thus adapted only for gripping and holding. The popular idea that a snake slavers its prey before engulfing it is incorrect; the saliva is never poured forth until the prey is well within the snake’s maw.

The great family of colubrine snakes is well represented in South Africa. Some are venomous; some are not. But the venom of a colubrine snake is usually far more deadly than is that of any viper. The head of the family is the mamba, Dendraspis angusticeps, which is the longest venomous snake in the world. This distinction was formerly claimed for the Indian hamadryad, which, however, does not appear to reach a length of more than twelve feet. I have personally measured a mamba thirteen feet four inches in length, and they probably run to fifteen feet in exceptional instances. The mamba is, moreover, undoubtedly the most dangerous of all snakes. Not alone is its venom deadly, but it is highly aggressive at times and its speed is quite extraordinary. If disturbed during the pairing season, the mamba attacks without hesitation; and if at any time one happens to get between the mamba and its dwelling, the snake rushes straight for its objective and, in passing, strikes swiftly as lightning at the intruder. The mamba’s fangs — two on each side — are long, deeply grooved, and powerful, and the amount of venom injected when they are buried in the flesh of a victim is much more than is necessary to cause death.

The mamba is very thin in proportion to its length. Occasionally, on being disturbed, it puffs itself out, thus considerably increasing the girth. It is primarily a tree snake, but is sometimes found in open spaces. It progresses in a series of bounds, suggestive of the successive uncoilings of a steel spring. The eye is large, round-pupiled, and expressive of intelligence. There are two varieties of the mamba — one colored a vivid grass-green and the other steely black. There is still some uncertainty as to whether one or two species exist. Mambas are common in parts of Natal, in Zululand, and in the northeastern Transvaal. Some years ago certain stretches of scrubby forest land near the mouth of the Umkomas River in Natal were left unoccupied by both Europeans and natives on account of the prevalence of mambas. To-day, in Zululand, the news that a large mamba has been seen will cause the vicinity to be shunned — perhaps for months.

The mamba, like most colubrine snakes, is oviparous. The eggs are often laid among dead leaves between the protruding roots of trees. Soon after being hatched the young snakes ascend among the branches, where their protective coloration makes them difficult to discern. They live upon eggs, birds, and small mammals. The mamba has the habit of lying coiled among the branches adjacent to a footpath in a forest. Woe to the passing wayfarer in such a case! If he touch a twig, and thus impart the least tremor to the snake’s lair, a lightning-swift stroke upon face, neck, or arm seals his doom. Such a st roke may be delivered either forward or sideways, with equal speed and effectiveness.

Another formidable colubrine reptile is the cobra — Naja haji, Naja flava, and t he rest. These snakes, only slightly different from the Indian cobras, often attain a length of over six feet. Their venom is the deadliest substance known; I am not aware of anyone having recovered from a cobra’s bite. Cobras vary much in coloration; I have killed adult specimens of alight lemon-yellow, jet black, and all intermediate shades. The cobra is a fierce fighter and, when reared up, with expanded hood, looks very formidable indeed. Anterior to the head the ribs lengthen and then gradually shorten to normal dimensions. These lengthened ribs, about twenty in number, lie, when the snake is quiescent, more or less laterally along the spine. But when the snake becomes excited, the neck bends and the ribs spring out at right angles. Over them the loose folds of skin expand umbrella-fashion. When much enraged, the cobra spits drops of venom at its enemy. These are propelled a distance of about four feet.

The fangs of the cobra and the mamba are not erectile as in the case of the vipers, but are fixed in position, ready for action, at the anterior ends of the maxillary bones. They are deeply grooved, and occasionally the sides of the groove lap over and form a tube. Into this the poison is led by a duct from a gland which lies imbedded in the maxillary muscles. The latter, when the snake strikes, become strongly constricted and force a jet of poison through the duct. The fang is easily broken, in which case another soon takes its place. The number of possible replacements is indefinite. A microscopic examination of the tissues at the base of the fang reveals myriads of supplementary fangs in various stages of development, some being less than a two-hundredth of an inch in length.

The cobra is found all over South Africa, but is especially plentiful in the dry, sandy deserts to the northwest, in and beyond the Cape Province. Here extensive colonies of large mice abound, patches of ground thirty yards in diameter being thickly honeycombed with burrows. In these the cobras dwell — apparently, as in the case of the puff adders, on the best of terms with their hosts, upon whom they principally feed. It would seem as if the mice had resigned themselves to paying a certain toll to their formidable guests. However, it is probable that the mice revenge themselves by seeking out and destroying numbers of the cobras’ eggs. The snakes are seldom seen. Occasionally — for instance, on an exceptionally cool day in summer — they emerge. In winter they hibernate, and on an ordinary summer day the sand becomes so hot that any snake attempting to crawl over it would immediately be scorched to death. However, their frequent zigzag spoors show that cobras are in the habit of emerging at night.

The cobra is an incorrigible robber of birds’ nests. Among the rocky hills fringing the desert its presence is often revealed by a swarm of angry birds. These circle around the marauder, screaming, pecking at it, and beating it with their wings. The bite of the cobra is fatal to all snakes, the cobra itself included.

A close relative of the cobra is the ringhals, or ring-neck, so-called from the presence of two black bands across the throat. This snake — Sepedon haemachates — is also widely distributed. In superficial appearance it resembles the American rattlesnake. The ringhals, when excited, exudes a quantity of venom, which drips down the fangs and lodges behind the abrupt, horny lower lip. Upon this the angry snake directs a blast of air through its extensible wind-pipe, with the effect that a jet of fine venom-spray is emitted toward an enemy. This jet may reach a height of six feet. That the eyes are aimed at, I have proved by experiment. If the poison reaches them, blindness — which may be permanent — results. The bite of the ringhals is highly venomous, but the snake appears to prefer disabling its enemy by means of the spray of venom.

II

The puff adder — so called from the loud, guttural, warning hiss which it utters when disturbed, is about thirty inches in length, with a girth of about six inches. It has tubular fangs about three fourths of an inch long. These are attached to the anterior maxillary bone by a hinged process, which corresponds with the zygomatic arch in the higher mammals. Until brought into action, the fang lies back along the maxillary, under a protecting membranous sheath, — the vagina dentis. When one fang is broken or dislodged, another immediately takes its place. In the valley of the Shire, a tributary of the Zambesi, the puff adder attains a length of five feet, with a girth equal to that of a man’s thigh, the fangs being correspondingly huge.

The coloration of the puff adder is in groundwork a series of delicate browns, with more or less regular curved transverse patches darkening to black and edged with vivid yellow. Its scales are keeled; its short tail tapers suddenly to a point. It is a sluggish creature, incapable of swift progression. When disturbed, it flattens itself to the ground, the air expressed in the process causing the warning hiss which has saved many a life. But if the foot of the intruder touch it, or even tread in its immediate vicinity, the puff adder lunges either forward or sideways, with a swiftness that the human eye cannot follow, and, having buried its fangs deep in the flesh, holds on like a bull-dog, forcing two streams of venom into the tissues. The expression of this snake, — its square muzzle and glaring, lidless eyes with vertical pupils, — the extraordinary gape of the jaws, and the huge, erected fangs, form what is probably one of the most fiendishly menacing combinations in Nature. Nevertheless, apart from its head, the puff adder is a creature of great beauty — more especially in spring, when the old skin has recently been sloughed off. The rich tints shade into each other in a pattern of bewildering complexity, and the curved, transverse markings form a tracery full of symmetry and grace.

It is to the great length of the puff adder’s fangs that the comparatively large number of recoveries on the part of human beings unfortunate enough to get bitten is due. This seeming paradox is explained by the circumstance that the venom is usually deposited deep down in the areolar tissue, between the blood-vessels. So that, if immediate incisions be made and a ligature be applied, the outflow of blood will probably carry the venom with it. The nearer the surface of the body, the more crowded are the blood-vessels, and the venom of a short-fanged snake is thus more likely to get rapidly into the circulation than is that of one with long fangs. But if the venom be discharged into an artery or vein, death will result within a few minutes, owing to clotting of the blood. Nevertheless, the venom of the viperine is not nearly as swift in its action or as deadly as is that of t he poisonous colubrine snakes. The puff adder is not affected by its own venom, but most colubrine venom injected into its tissues will cause death.

The food of the puff adder consists of rats, mice, frogs, toads, and other small animals. Like most South African snakes, puff adders eat each other. If two, one larger than the other, seize an animal at the same time by opposite ends, the jaws of the larger snake will, on meeting, close over those of the smaller one, and the latter, as well as the prey, will be swallowed. In dealing with a toad or a very small animal, the puff adder will seize and swallow it without using the poison fangs; but in the case of a larger rodent, the snake will strike, let go, and wait until the victim collapses before swallowing it.

There are various other members of the viper family in South Africa, all more or less deadly. One, Bitis atropos, usually inhabits high plateaus and mountain ranges. Another, Bitis cornuta, the ‘horned adder,’ — so called from the groups of erect scales resembling horns which grow over the eyes, — inhabits desert places and has the habit of burying itself in the sand at the base of a grass tussock, with only the head emerging. It is in point of species almost identical with the ‘worm of old Nile’ which Cleopatra employed to ease herself of her burden of life.

The ‘night adder,’ Causus rhombeatus, is much dreaded on account of its habit of lying at night in pathways and failing to move out of one’s way. This snake is one of the exceptions to the rule of the viper class, in that it is not viviparous. It has another remarkable peculiarity: the poison glands, instead of lying compactly imbedded in the maxillary muscles above the angle of the jaw, are much elongated, and lie one on each side of the spine. They are connected with the fangs by long ducts.

Another aberrant genus is Atractaspis, of which two South African species have been recognized. These have adopted the habits and appearance of the blind burrowing snakes (Typhlops), which are non-venomous. These vipers also are oviparous. They have fangs so abnormally developed that the mouth cannot be opened wide enough to admit of their being erected.

One of the most interesting adaptations found among snakes is that of the non-venomous ‘egg-eater’ — Dasypeltis scabra. This creature is only about eighteen inches long, with a diameter of about three fourths of an inch. Yet it will swallow an ordinary fowl’s egg without difficulty. Its teeth are rudimentary, but it has extraordinary power of expansion of the jaws and neck. The neck vertebræ have developed spines—hypapophyses—which slant forward and pierce the esophagus. After the egg has been swallowed, the snake lifts its head and neck, and works the egg backward and forward against the spines, which act like a saw and cut the shell. The egg collapses, the contents run into the stomach, and the shell with its membrane is ejected.

Another interesting class of snakes is the Opistoglypha. In their case the grooved poison-fangs, which are very small, are fixed, not at the anterior end of the maxillary bone, but behind the orbit of the eye. Consequently, they are but seldom brought into action. The largest South African example of this class is the ‘boomslang’ or ‘tree snake,’ — Dispholidus typus, — which is to be found wherever trees abound. The boomslang grows to the length of about six feet and varies in color between vivid grass-green and dull brown. Like the mamba, it has the habit of puffing itself out when interfered with, until its girth is more than doubled for two thirds of its length. The boomslang was, until recently, looked upon as non-venomous. I have handled them freely and often prevented their being killed. However, in 1907, Mr. James Williams, who was employed as snakecatcher by the Port Elizabeth Museum, was bitten by one in the arm, and narrowly escaped with his life. Thereupon Mr. Fitzsimons demonstrated, in the course of some interesting investigations, that the boomslang, as well as other species of the Opistoglypha, is not only venomous, but deadly.

The only sea-snake found in South Africa is Hydrus platurus, which ranges from Southern Asia down the eastern coast of the African Continent as far as the Cape of Good Hope. From there the cold current prevents it going north. This snake — one of a large genus — measures about two feet. It is black above and yellow beneath, and has a vertically flattened tail. Hydrus platurus is highly venomous, its poisonapparatus being as intricately developed as that of the cobra, to which it is related. This is remarkable, in view of the flattened tail and the position of the nostrils, which indicate that it has been a sea-dweller for an immensely long period. The venom can be of little or no avail against the cold-blooded creatures upon which this snake preys.

The largest of all South African serpents is the python, — Python sebae, — which occasionally attains a length of over twenty feet, with a circumference of eighteen inches. One is recorded as having measured twenty-five feet. The color-scheme of the python is yellowish brown, various tints of which are harmoniously arranged in darker blotches upon a lighter background. Near the vent are two claws — evidently rudimentary survivals of limbs; corresponding with them is a rudimentary pelvis. The python principally frequents rocky chasms in moist, warm forests. It is not dangerous to man, being quite non-venomous. It will, however, fight fiercely if attacked, and the long, sharp, recurved teeth may inflict a severe bite. The python usually preys upon small animals, such as minor antelopes, monkeys, coneys, and birds. Sometimes this snake coils itself at the bottom of a stream and lies with its nose just emerging. When a small buck comes to drink, the snake seizes it by the nose, the recurved teeth taking an inextricable grip. After the buck has been drowned the python coils itself around the body and crushes it into an elongated mass, for convenience in the process of swallowing. The saliva of the snake flows freely, but only over that portion of the prey which is engulfed. The python does not regard the horns, which are occasionally to be seen sticking out through its abdomen. When the carcass, including the bones, has been dissolved in the powerful gastric juices, the horns drop off and the holes fill up, the snake apparently being none the worse for the perforations.

So far as I know, the python is the only snake which incubates its eggs. Such, numbering from thirty to fifty at a brood, and weighing about five and one-half ounces each, are usually laid in a deep rock-crevice or in the deserted burrow of an ant-bear or a hyena. The mother coils herself over and around them. During the incubation period the snake’s temperature rises somewhat.

Many snakes not only are harmless, but are distinctly beneficial to man, in that they tend to keep the barns and dwellings they frequent clear of rats and mice. The mole-snake — Pseudaspis cana — grows to a length of more than seven feet. It, unfortunately for itself, bears a certain superficial resemblance to the cobra. It is viviparous and extremely prolific; one case is recorded of a brood which numbered eighty-four. The mole-snake, which lives upon animals nearly all of which are mischievous to man, constricts its prey after the manner of the python. It may here be noted that no venomous snake practises constriction.

It is very unfortunate that these useful and innocuous snakes have to suffer on account of the vices of their relatives, but it is quite useless to expect the average person to discriminate between the venomous and the non-venomous varieties. Even wild animals, whose perceptions are far keener than those of man, cannot do this. A captive baboon, for instance, will exhibit as much terror in the presence of a non-venomous snake as in that of a cobra or a puff adder. This raises an interesting possibility. May it not be that at one time all snakes were venomous, but that in certain instances the poison-fangs have disappeared and the venom has become merged in the gastric juices, which form the most powerful known solvent of animal origin ? How far the venom of the cobra and the gastric juices of the mole-snake are homologous is a question I have often speculated upon, but have had neither the opportunity nor the technical skill to investigate.

III

Practically all South African snakes take to the water in hot weather. They swim freely across both rivers and salt tidal lagoons. Sometimes they lie coiled on the surface of the water, fast asleep — the long, single lung being inflated to provide the requisite buoyancy. In some localities, boating at night in hot weather is distinctly dangerous; for snakes are apt to coil about the oar without being observed, and thus get into the boat. But there are several species of snakes which are practically amphibious. These inhabit the margins of streams and pools, and prey on frogs and small fishes. It is their habit to climb trees suitably situated; from these, they dive and pursue their quarry to considerable depths. None are venomous.

The green water-snake — Chlorophis hoplogaster — is, when gliding sinuously through clear, still water, probably unequaled for beauty in the animal kingdom. The liquid medium enhances its gloss, until it resembles a living emerald. Its rhythmic curves weave patterns graceful almost beyond the possibilities of imagination. Another, — Ablophis rufulus, — olive and pink in color, is almost incomparably beautiful. One recalls Coleridge’s lines:

Within the shadow of the ship
I watched their rich attire;
Blue, glossy green, and velvet, black,
They coiled and swam; and every track
Was a flash of golden fire.
O happy living things! no tongue
Their beauty might declare.

Were it not for the fact that snakes are wholesale and consistent cannibals, these creatures would increase to a very embarrassing extent. Even the mother snake has usually no compunction in the matter of eating her offspring. The snake has many enemies: the mongoose, the meercat, and the badger destroy large numbers. So does the secretary bird, which provokes the snake to attack and, when the latter lunges, dashes forward with wings expanded to form a shield, and thus flings back the attacker. After these tactics have been repeated several times, the snake becomes exhausted, and then the bird rushes in and with a nip of its powerful beak dislocates the spine just behind the head. The great turkey buzzard seizes the snake just behind the head, flies spirally into the air to a height of several hundred feet, and then drops its victim to the ground.

But in regions closely settled by human beings, the most deadly and relentless enemy of the serpent tribe is the domestic cat. The snake is, unless the weather be cold, largely a nocturnal hunter. It lies in wait on the pathways used by small rodents — on the margins of pools and water-courses frequented by frogs. The cat stalks the stalker, pouncing after the latter has seized and partly swallowed its prey and is thus relatively helpless. The cat is fully alive to the danger of his sport, and invariably endeavors to inflict a disabling bite in the vicinity where the spine of the reptile joins the head. The rapid disappearance of snakes from the vicinity of human habitations is undoubtedly due to the ‘harmless, necessary cat.’ The latter appears to be proud of its achievements in this line, and will often bring home a freshly killed snake with every appearance of satisfaction. I have known several cats with whom this was a habit.

The real nature of snake-venom is still mysterious. It is evidently an albuminous substance containing complex and highly specialized proteids, which induce numerous and varied pathological conditions, and consequently symptoms quite dissimilar. The poisongland of the average venomous snake and the parotid salivary gland of the mammal are homologous. There is probably considerable affinity between human saliva and snake-venom. The latter has been kept for upwards of thirty years without its toxic powers becoming weakened. The pathological effects of some venoms on the nerves strongly resemble those induced by curare.

The effects of snake-venom can be counteracted only by means of serum taken from the blood of immunized animals. One by one the so-called remedies — often widely advertised — have been tested and found useless. Unfortunately it is but seldom that the serum is at hand when required. The venom of each individual species of snake has a special toxic effect: immunization from the effects of the bite of a puff adder, for instance, does not involve immunization in respect of the bite of the cobra or the mamba. Venom has three well-marked separate toxic consequences: it is a nerve-poison, a blood-poison causing the corpuscles to break down, and a ferment which induces coagulation in the fibrin of the blood. Colubrine venom has primarily a nerve-effect; viperine acts mainly on the blood. The nerve-centres controlling the pulmonary system are those primarily affected; in every fatal case which has been professionally observed, the heart has continued beating after breathing has ceased.

The so-called ‘wisdom of the serpent ’ is completely mythical. The mind of the serpent is inferior to that of all mammals and birds and to that of many fishes and insects. A dull, senseless malignity is its most outstanding characteristic, but of wisdom it has hardly more than the oyster or the clam.

Physically the serpent is a creature of most marvelous adaptations. Moreover, it exhibits great beauty in its coloration and consummate grace in its movements. It possesses a considerable share of that low form of vitality which is characteristic of inferior, slowblooded organisms. For instance, a snake’s heart may beat for a whole day after its head has been cut off, or for a quarter of an hour after removal from the body.

Mystery and terror are instinctively associated with the serpent; myth and legend show that this tendency has existed since the dawn of the human intellect. The instinctive dread which the serpent induces is not confined to the human race. The hiss of a snake will fill most animals, although they may never have heard such a sound before, with dread; even as the howl of a wolf, in a country where wolves were exterminated centuries ago, will drive horses and cattle mad with panic. It is one of those trumpet-calls of elementary dismay which wake echoes in that wondrous labyrinth, the germ-plasm, within whose caverns lurk all the terrors and tragedies of the immeasurable past.

  1. The author wishes to acknowledge his indebtedness to Mr. F. W. Fitzsimons, F.Z.S., etc., Director of the Port Elizabeth Museum, whose book, The Snakes of South Africa, contains extensive and useful information.