The Orycteropus, which means digging-up foot, from ὀρύσσω (to dig up), and πούς (foot), is the deadly foe of the Ants of all kinds, and especially of those which, like the White Ants, live in large colonies and build nests.
These nest-building Ants abound in certain districts, but not in the region of the downs or karoos, nor where it is very dry and woody. They choose the country which is covered with a poor and so-called “sour” grass, and there they dig galleries in the ground, fetch earth from far and wide, and erect large rounded mounds of an elliptical figure, and often from three to seven feet in height. Apparently fond of company, the Ants congregate, and these gigantic hills of theirs are often crowded together and occupy the plains, as far as the eye can reach. The nests, or hills, are solidly built, and contain innumerable ants. This is the favourite resort of the Orycteropus, and the insects are his sole food then. Wherever ant-hills are found, there is a good chance of finding one of these Aard-varks, or Innagus, or Ant-Bears, as the Dutch and natives call them, leading a sort of mole-like life. But he is not easy to catch if the stories told be true. It is stated that the long strong flattened claws and short extremities, worked by their strong muscles, enable the animal to burrow in the soft soil as quickly as the hunters can dig, and that in a few minutes it will get out of the way; moreover, its strength is sufficient to resist the efforts of two or three men to drag it out of the hole. But when fairly caught, the Ant-eater does not resist much; it has no front teeth or eye teeth to do any harm with, and it can be killed easily by a blow on the head. The Ant-eater runs slowly, and never moves far from the entrance of its burrow, being seen to do so only at night-time. The burrows are often two feet in diameter and three or four feet deep before they branch off. Night is the time for Ant-eating, for the active and industrious insects are then all at home and within their solid nests. Then the Orycteropus sallies forth, finds a fresh nest, sprawls over it, and scratches a hole in its side, using his strong claws, and then introduces his long snout. Having satisfied himself that there is no danger at hand, the animal protrudes its long slimy tongue into the galleries and body of the nest, and it is at once covered with enraged Ants, which stick to it, and are finally returned with it into the mouth. This goes on over and over again, until the appetite is satisfied; and apparently the diet is excellent, for the Ant-eater is generally fat, and indeed his hams are appreciated as a delicacy for their peculiar flavour, into which that of formic acid is said to enter.
CAPE ANT-EATER.
Although without an armour to its body, and provided with only a thick skin and bristles, the Orycteropus has a great resemblance in many points of its anatomy to the Armadillos of America. It is more closely allied to them than to the other Edentata. It is one of the order of Edentata, for there are no front teeth in the jaws, the incisors and canines being absent. The teeth are found in the back part of the mouth, and there are five on each side and in the upper and lower jaws, or twenty in all; there are also some small teeth which fall out during the growth of the animal. As might be expected from the very simple nature of the diet, the teeth are not at all complicated in their structure. They increase in size from before backwards, the last tooth but one being the largest, and all are peculiar in their minute construction. The first permanent tooth, which may be called a molar, is cylindrical in shape, and consists of a centre of very remarkable substance, for the body of the tooth is composed of a great number of vertical canals placed side by side, and running up the tooth. It was this interesting structure, so different to that of other animals, which led Cuvier to compare the teeth to pieces of cane. Outside this part of the tooth is a hard and more solid substance. When the teeth are unworn, this outer covering covers their top, but as it wears off the tubular appearance is seen, and the ends of the tubes become exposed. The teeth have no fangs like those of such orders of Mammalia as the Carnivora and Insectivora, and they increase in length by growth from below, so that the wear above is continually compensated for. The second tooth resembles the first in its minute construction, but appears like two cylinders fixed together, a longitudinal groove indicating the junction, and this is the appearance presented by most of the others. The hindermost teeth resemble the first molars. The dental number varies according to age, and the presence or absence of the teeth which are not permanent. The jaws, in which the teeth are fixed, are long, and the lower one is low, but there is an ascending back part, or ramus; consequently, the face is long and low. The eye is placed far from the ear, and is small. Its bony case, or orbit, and its surrounding bones, are somewhat remarkable for an Edentate, for there is a lachrymal bone, and the tear canal is open on the bony face. Moreover, the malar bone is united to the ear bone by a complete arch, the zygoma, and the deficiency so remarkable in some other Edentates is thus not observed. The pre-maxillary bones are also to be seen, in front of the face. In this completeness of the bones of the face this animal is a true mammal, but in the nature and extent of the ear bones, the Orycteropus has some resemblance to reptiles and birds.
SKULL OF THE CAPE ANT-EATER.
The tongue is long, narrow, and flat, and can be protruded considerably beyond the mouth, but not so far as those of the other insect-eating Edentata; and in order to keep up a supply of thick mucus, the glands under and at its side, or the sub-maxillary, are very large and active in their functions. The stomach is moderately bulky and not simple, for the portion towards the right has very thick muscular walls, and the rest is thin. The intestine has a blind gut, or cæcum.[63] In fact, the stomach and blind gut might belong to an animal which eats something more bulky and less nutritious than Ants, and would be of use to the creature, did it eat vegetable matters. All these structures, the simple teeth, the tear bones, the size of the ear bones, the Sloth-like teeth, with tubes, however, and the peculiarities about the intestinal canal are, it must be remembered, associated with the life of a purely insectivorous animal. Why has it not the kind of teeth of the Insectivora and their stomach? and why should it combine high and low characters in its skull? These are questions which, when attempted to be answered, show that in the great philosophy of nature causes and effects are not everything, and that the same definite methods of life may be followed by animals very differently constituted.
The claws of the Orycteropus and the limbs are admirably suited for its kind of life. There are five claws on the hind limbs and four on the front, and they are long, slightly curved, flat, and scooped out below. The burrowing is facilitated by the arrangement of the claws as regards length, and they diminish in size from within outwards. There is a collar bone. The foot rests evenly on the ground and not on its outside, and the body is supported either by the whole foot or by the palm surface of the claws. The fore arm can be rotated more or less, and the pronator quadratus[64] muscle enables this necessary action to be carried out. The Orycteropus capensis lives over a wide extent of country in South Africa, in Caffraria, and in the western districts. A closely-allied species lives in Senegal (Orycteropus senegalensis, Less.); and a third is found in Southern Nubia, near the White Nile (Orycteropus æthiopicus, Sund.).