Invertebrates from Madagascar

Notes from James Sibree's A Naturalist in Madagacar
(Seeley, Service & Co.: London, 1915)

In passing along the forest paths we frequently come across examples of the curious ball insect (Spherotherium sp.), of which there are several species, at least six, in Madagascar. These insects, which are wingless and many-footed, and are called, not very elegantly, by the Malagasy Tainkìntana, or "Star-droppings," have the power of instantaneously rolling themselves into an almost perfect sphere, which form they retain as long as any danger threatens them, and no force short of pulling them to pieces can make them unroll. The animal is formed of nine or ten segments, each with a pair of legs and covered with a plate of armour; while the head and tail are defended by larger plates, each of which fits into the other and makes a more perfectly fitting suit of armour than was ever worn by medieval knight. There are several species of these pretty and curious creatures. The most common kind here is one which forms a ball barely an inch in diameter and shining black in colour. Another, more rarely seen in the interior open country, but common enough in the upper belt of forest, is of a beautiful brown colour like russia leather, and is quite double the size of the first-mentioned one. In passing through the main forest in 1892, we came suddenly one day to a part of the road which was so thickly covered by such a great number of these creatures that our bearers could not avoid trampling on them. These were of a bronze-green tint and belong to a third species, and were quite three inches in length. Other species of these Sphærotheria are found in Africa, Asia, Australia and some of the neighbouring islands.

Another many-footed and wingless creature is common enough in the upper forest, for we often found it on the upper verandah of the house at Andràngalòaka; this is a shining black millipede, about a foot in length, and half to three-quarters of an inch in thickness. It is called by the natives Kòdikòdy, and its numerous reddish legs, not far short of a thousand in number, have a curious effect of successive waves as it moves along. Although not very inviting in appearance, it is quite harmless and is a vegetable feeder. There is another species which is marked longitudinally with black and red stripes.

More unpleasant by far is another many-legged creature, the centipede, whose sting is said to be exceedingly painful, resembling the puncture of a hot iron, and which is not uncommon in the interior as well as in the forest. The mere touch of its minute claws, if it happens to crawl over one, is said to produce pain and inflammation. I have turned small centipedes out of the hole in a window-sill where the bolt would fall; and I remember one morning, before getting out of bed, seeing a pretty large one marching across our bedroom floor. Happily these, which are among the few noxious creatures we have in Madagascar, are not very common. Another unpleasant visitor is the scorpion, which is rather apt to get into a house which has much stonework in the basement; we frequently killed small ones about an inch long at Antanànarivo. Examples twice that size are found in the Vàvavàto district; while on the shores of Bèmbatòka Bay (N. W. Co.) scorpions five inches long occur, and Captain Owen says that they may be found, one or more, under almost every stone. He states a curious fact, if indeed it is one — viz. that the most destructive enemy to the scorpion is the common mouse.

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As the colder weather advances, the mornings are often foggy, at least a thick white mist covers the plains and valleys soon after the sun rises and remains for an hour or two until his increasing power disperses it. Seen from the higher grounds and from the most elevated parts of the capital, this mist often presents a very beautiful appearance; a billowy sea of vapour is brilliantly lit up by the sunlight, and out of this sea the hilltops rise up like islands. But these misty mornings also reveal many things which cannot be seen, or can only be seen by very close observation, in clear sunshine, especially the webs of various species of spider. There they are all the time, but we are not aware of their presence except on a misty autumn or winter morning, when a very delicate thread and filmy net is marked out by minute drops of moisture which reveal all their wonderful beauty of structure. Many kinds of bush are seen to be almost covered by geometrical webs: one species seems to choose the extremities of the branches of the sòngosòngo Euphorbia, but the most common is a web averaging five or six inches in diameter which is spread horizontally on tufts of grass, and may be seen by thousands, half-a-dozen or so in a square yard. This web has a funnel-shaped hole near the centre, with a little shaft leading down to the ground. Near this, the maker and tenant of the structure — a little greyish-brown spider about half-an-inch long — may often be found, if carefully searched for. As the sun gains power, these numerous webs become almost invisible, but before the moisture is all dried from them, they present a beautiful appearance in the sunshine, for they are exactly like the most delicate gauze, studded with numberless small diamonds, flashing with all the prismatic colours as we pass by and catch the light at varying angles.

The most conspicuous of the many species of spider seen in Madagascar is a large Nephila, a creature about an inch and a half long, with a spread of legs six or seven inches in diameter. It is handsomely marked with red and yellow, and may be noticed by scores in the centre of its geometric web stretching across the branches of trees. From the considerable distances spanned by the main guys and supports of its great net, this spider is called by the Malagasy Mampìta-hàdy, or "fosse crosser"; and these main lines are strong enough to entangle small birds, for at the mission station at Ambàtoharànana a cardinal-bird and a kingfisher were both caught in these nets. The male spider is only about a quarter the size of the female as just described, and, sad to say, he frequently is caught and devoured by his affectionate spouse, after mating. Attempts have been made, and with some success, to employ the silk made by this spider in the manufacture of a woven fabric; but it is very doubtful whether such silk could be procured in such quantities as to be of commercial value.

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While on the subject of noxious creatures we remember that one, if not more, of the spiders of Madagascar must be included in the list. This is a small arachnid, about the size and shape of a marble, shining glossy black in colour, except for a small red spot on the fundament. It is greatly dreaded by the natives, who believe its bite to be fatal, and it is probably so if cauterisation and other remedies are not immediately applied. Dr. Vinson, a French naturalist, ascertained that this spider, called Mènavìny by the people, is closely allied to the malignant Latrodectus of Elba and Corsica, whose bite is believed to be fatal, and also to another spider found in Martinique, which is equally dangerous. People bitten by this Madagascar spider scream out with pain at intervals of a minute or two, as if it came on in paroxysms. I remember that one of our servants when bringing one of these spiders to look at took care to hold it at a very respectful distance from himself, at the end of a long stick.

As we push through the bushes we break through many spiders' webs, and are struck by the extraordinary shape of some of those whose snares we unwittingly destroy by our passing along. Here is one, small and reddish in colour, but much broader than it is long, each side projecting into a long sharp spike — indeed it is spiky in several directions, and is utterly unlike any other spider we know of. This is, I believe, a species of Cærostris (C. stygiana ?), and belongs to a genus of which several species have names denoting their demoniacal shape and colouring—e.g. avernalis, stygiana, etc.

As we stop to observe his geometric web, and his bizarre shape, we see on the tree to which several of his main "guys" are fixed a very different spider's house and a very different spider from our angular friend just mentioned. This creature is a much larger species than the other, with jet-black legs and satiny dark grey abdomen as large as a good-sized nut. He apparently hunts his prey, for he has no net, but hides himself is an inverted cup-shaped house of strong web. As I tap the top of this retreat he shams dead and tumbles down into the grass, from which he will presently ascend as soon as the enemy is clear off the ground.

Close by this hunting spider's home we see the large web of a third species, quite different from the other two. At first sight this appears to be the same insect as the large Nephila, which is so plentiful in Imèrina, in orchards and outside houses. A closer inspection, however, shows that it is a different species from that common large spider, for this one has a long filbert-shaped abdomen, striped with brown lines, very different from the golden and silvery markings of the more abundant species. It appears to be strictly a forest spider and seems rather rare.

In rambling along the edge of one of the pretty rice-valleys north of Ambòhimànga, I came across a species I had not met with before. This was of medium size, but was striped in transverse lines of white and black across the abdomen, so as to give it a zebra-like appearance. The under side was almost white; altogether it is a handsome species, and is probably still undescribed scientifically. It makes a geometrical web, and, like several other Madagascar spiders, puts the web into rapid vibration if it is disturbed. Some species draw up their legs close to the body when lying in wait in the centre of their web, so that they too resemble a small lump of earth or a stone. Is this also done as a disguise? It seems to me highly probable. Other species have the habit of stretching out their legs in couples, so as to seem almost as if they had only four or six legs instead of eight, and thus appear to mimic insects. Is this also intended to hide their predaceous character?

A traveller through the Tanòsy country, south-east coast, speaks of the uncanny aspect of one of the villages in which he stayed; and he says that what increased his impression of it, as like a town of wicked enchanters, was that all the houses were festooned and closely linked together overhead by tangled masses of gigantic spiders' webs, amongst which lay in wait monstrous black spiders. Some of the coast villages, he says, were almost completely roofed in by these great webs. Spaces of quite thirty feet have been observed spanned by the lines of the nephila mentioned in a former chapter; and I have noticed that the angles and outer spaces of its great web are frequently filled up by the minute geometric webs of smaller species. These lesser fry appear to be tolerated, if not encouraged, by their giant neighbour, as they probably catch what would be insignificant to her, and very likely clear her web of what she rejects; and so they all live together in harmony in a small colony.

Looking about in the undergrowth for wild flowers and fruit, and happening to rub against the stem of one of the bushes, a small rough roundish ball falls off on to the ground; this appears exactly like a bit of round wrinkled bark, but on watching for a minute or two, it develops four pairs of legs, and runs nimbly away under cover, revealing itself as a spider, with a marvellous protective resemblance to its surroundings. Unless the creature actually moves, it is impossible to detect it, it is so exactly like a knobby bit of the brown bark.

Protective resemblance in quite a different style appears in a small spider, perfectly white in colour — thorax, legs and abdomen — which scuttles out of the coralla of certain white flowers when these are examined or shaken. This also, unless it moves, is all but invisible; and there can be no doubt that it is thus enabled to catch the many small flies which are attracted by the honey and fragrance of the flowers. A larger and green spider, a handsome species, with a long oval abdomen striped with red, probably also a hunter, thanks to its close resemblance to green leaves and the pale reddish veining seen on many leaves, by which it is thus protected from observation until it can pounce upon its prey. This is one species of the many spiders which are caught by some of the solitary wasps, as described in Chapter VII.

As we notice these curious disguises in spiders, as well as in numbers of other living creatures, we are reminded of the old nursery tales and fables of the gift of invisibility supposed to be conferred by certain plants, or by certain charms or ceremonies. With these spiders, as well as in many other creatures, some lower, and others much higher, than them in organisation, this power of becoming at will unseen, even under the closest observation, is no fable, but a veritable fact. There is a curious habit which I have observed in several species of Malagasy spiders which is apparently also used for protection. If they are disturbed, or if their web is shaken, they immediately throw themselves into a state of violent vibration, so that the eye cannot follow them; and this rapid motion is continued for two or three minutes, until the supposed danger has passed away. It would seem as if this must be done to confuse a possible enemy intending to attack them.

Besides the red-spot spider, there is another kind called by the natives Fòka; this is rather common in gardens and is extremely like a small crab, with a lozenge-shaped abdomen; it is covered with tubercles, and its legs are roughened, like those of a crustacean. Its bite is followed by swelling, which spreads from the wounded part through the whole body. This dangerous spider's bite is said to be often fatal. There is another spider, apparently a species of Mygale, called by the people Tàrabìby, found fifty to sixty miles west of the capital, whose bite is also said to be dangerous, if not actually fatal. It appears to be a trap-door species. Besides this one, another species of trap-door spider is also said to be found in Imèrina, but I have not a specimen myself; it is said to leave the door of its dwelling open.

The illustration given herewith will give a better idea than any mere description can of the strange shapes of many Madagascar spiders. The largest figure shows an Epeira of extraordinary shape; it will be seen that the abdomen is like a set of three cones, fixed into one another and terminated by a sharpish point. A still more bizarre figure is presented by Epeira mitralis, as it crouches, fixed close to a branch or twig; whether viewed from the back or front or side, it is equally "uncanny" in its appearance. Then, again, the two Gasteracanthæ, with their bodies much broader than they are long, are very unlike our ordinary idea of a spider, while the formidable likes with which they are armed would appear a very efficient protection from any insect-eating bird or beast. The rather diabolical-looking Thomisus foka, with its crab-like pincers, is much dreaded by the Malagasy, as giving a fatal bite, if speedy remedies are not applied. Happily, it is not very common.

Arachnids

Myriapods

There is a considerable variety in the webs of Malagasy spiders. Here is one which may be seen by hundreds, filling up the space between the sharp-pointed leaves of the aloes. At first sight it appears only a tangled mass of web, but on closer examination we see that the groundwork is a geometrical well in the centre, but as it is stretched horizontally, and not vertically, it is cup-shaped. But from it, above and below, stretches a labyrinth of lines, like the crossing and recrossing of the lianas in the forest. In the centre of this maze of lines the owner of the structure lies in wait, a small spider, handsomely marked with black and white. Not far off a grey silken bag is hung, which contains the eggs, from which a swarm of little spiders will eventually proceed, not bigger than small ants.

A word or two may be added about a very common house spider which is abundant in Imèrina. This is a rather large species, light brown in colour, but its peculiarity is that it is extremely thin and flat — a case almost of extension without thickness, as it is hardly thicker than a piece of stout paper, and so it is enabled to wait for its prey hidden in narrow and almost imperceptible cracks. It is emphatically a hunting spider and makes apparently no nest or web, and it is amusing to see the adroit way in which it will cautiously approach the edge of a crack in a board and sweep off an unwary fly.

One more curious spider may be noticed here; this has a very small body, hardly larger than a big pin's head, but it has extraordinarily long thread-like legs, covering a very wide area when compared with its minute body.

There must be still a large number of these Arachnidæ yet unknown to science, for they are very numerous in species in some localities. I remember spending an afternoon, many years ago, on a hill a few miles south of the capital, together with two or three friends, hunting spiders. We caught at least thirty different species among the bushes on the hill-top and slopes. Doubtless some of these are described and figured in one of the volumes of M. Grandidier's great work on Madagascar still in progress. But there are probably a much larger number of these creatures still awaiting the careful observations of anyone who will note their interesting habits and homes, and their very varied appearance and structure.

In our walks in the forest from the Ankèramadìnika Sanatorium (Chapters VIII. and IX.), we saw, it will be remembered, many cases of protective colouring. As we are again in the eastern forests, the following instances may also be noted. There is found in these woods a curious walking-stick mantis, about eight inches long and a quarter of an inch thick. It is exactly the colour of a dried branchlet or twig, with joints distinctly articulated like the nodes of many plants. The tail (if the end of the creature may be thus called) is rather more than an inch long, and is a hollow, canoe-shaped trough, somewhat resembling part of the bark torn off a twig. The legs are alate and spiny. At about two inches from the head are the wings and wing-sheaths, the latter being somewhat like obovate stipules about half-an-inch long, and the former marked with black and yellow and about an inch and a half long. When the wings are closed, it would take a very keen eye to discover the creature, as the part of the wing when closed is of the same colour as the rest of the body. The legs can be brought together lengthwise in front, and so appear to form a continuous part of the twig, especially as the femurs are hollowed out to form a socket for the head.