Africa possesses an abundant and varied population of arthropods (which include insects and other segmented invertebrates). Among them are found large butterflies of the Charaxes (brush-footed) and Papilio (swallow-tailed) genera, stick insects, and mantises, grasshoppers, driver, or safari, ants (tropical ants that travel in vast, serried ranks), termites, and dung beetles. Spiders abound throughout the continent, and scorpions and locusts can also be plentiful locally. Periodically, huge swarms of locusts spread over wide areas, causing enormous destruction to vegetation. Other serious pests are mosquitoes, which act as vectors in the spread of such human diseases as malaria, and tsetse flies, which transmit the parasite that causes African trypanosomiasis (sleeping sickness) in humans and nagana in livestock. Aquatic life
Freshwater fish include both remarkable archaic forms and examples of rapid recent evolution. Among the ancient forms are lungfish (Protopterus), bichirs, or lobefins (Polypterus), and reedfish (Calamoichthys), all of which can breathe air—a property also possessed by certain catfish (Clariidae), which are able to travel overland for some distance in wet weather. Characteristic of more recent evolutionary trends are the approximately 200 species of fish found in Lake Nyasa, four-fifths of which occur only there.
African lungfish (Protopterus annectens).Copyright Tom McHugh—Steinhart Aquarium/Photo Researchers
The coelacanth, an archaic marine form believed extinct for more than 60 million years, was discovered to be alive off the east coast of South Africa in 1938, and since then many others have been found. A rich and varied invertebrate animal life on the east and west coasts includes marine organisms typical of the Indo-Pacific and Atlantic oceans. Coral reefs and associated organisms are mainly found in the warm waters of Africa’s east coast, while the southwest and west coasts—washed, respectively, by the cold Benguela and Canary currents—abound in fish.
Coelacanth (Latimeria chalumnae)Peter Green—Ardea Photographics
Origin and adaption of African fauna
At one time most African fauna was thought to derive from elsewhere. There is no doubt, however, that as little as 15,000 years ago an amelioration of the present Saharan climate enabled such typical Ethiopian forms as clariid catfish to reach the river systems of North Africa. Likewise, Palaearctic animal life and vegetation appear to have extended far south into the Sahara, and the white rhinoceros apparently lived beside elklike, typically Palaearctic deer.
Within the Ethiopian region, repeated climatically controlled expansion and contraction of vegetational zones resulted first in organisms establishing themselves in numerous specialized ecological communities (niches) of plants and animals and second in the proliferation of those species that successfully adapted themselves to the prevailing conditions. The spread of forests during the pluvials, separating northern and southern wooded grasslands, led to the evolution of such closely related northern and southern species of antelope as the kob and puku, the Nile and common lechwe, and the northern and southern forms of white rhinoceros.
Some subfamilies of Bovidae, like the spiral-horned antelope (Tragelaphinae), have adapted to almost every ecological environment—forest, woodland, grassland, Afro-Alpine zones, and even to sudd vegetation. Others, like the hartebeests (Alcelaphinae), which inhabit savannas and grasslands, are less adaptable.
Freshwater fishes demonstrate the existence of the relation to one another of former river systems and lakes. Large rivers containing Ethiopian fish evidently existed quite recently in the northern Sahara. The fish life of the now-isolated Lake Rudolf (Lake Turkana), in East Africa, demonstrates that the lake was once connected to the Nile, though Lake Victoria, the present source of the White Nile, was not. Lake Kivu too was formerly connected with the Nile, but, as a result of volcanic activity, it is now part of the Congo drainage system.
In earlier periods the animal life was even more remarkable than today. Fossil deposits have revealed sheep as big as present-day buffalo, huge hippopotamuses, giant baboons, and other types similar to existing species. These huge types probably lived in pluvial periods, dying out as aridity increased. Smaller types survived. The effects of humans
Until they acquired firearms, humans made relatively little impact on animal numbers or—with some exceptions—their range. From the last half of the 19th century, however, and particularly since 1940, direct or indirect human wastage of Africa’s animal life has been intense and has reduced stocks considerably. The antelope known as the Zambian black lechwe, for example, believed to have numbered 1,000,000 in 1900, had been reduced to less than 8,000 by the late 20th century, and the population of African elephants declined from 2,000,000 in the early 1970s to some 600,000 by 1990, largely because of poaching for the ivory trade. The African white rhinoceros reached the verge of extinction in 1980.
Though European hunters and colonists were rightly blamed for much of the decline at its onset, hunting and destruction and the disturbance of habitats by Africans have become more important. Rinderpest, an acute and usually fatal infectious disease of livestock, entered Africa with domestic stock in the 1890s and ravaged herds of indigenous ungulates. The accelerated spread of agriculture and stock raising involving the destruction of forests, as well as heavy grazing and burning of vegetation, eliminated large animals from wide tracts. In South Sudan, for example, political strife and warfare in the 1960s entirely eliminated wildlife from some areas. The demand for fancy leather and fur has also endangered the Nile crocodile and the leopard.
Humans, however, have been of benefit to many smaller species. Dams and irrigation schemes, for example, have provided habitats for waterfowl, frogs, and fish, and the spread of grain crops has encouraged certain pests. Even the patchy cultivation of forests has resulted in the development of a mosaic of habitats that can provide new, if small, niches for some species. Ecology
There are still sufficiently large tracts of relatively unspoiled country in which animal life may be studied in its environment. The complementary roles of wild ungulates, for example, show that in any area inhabited by a wide variety of species, the grass is grazed in regular succession and at different stages of growth—for example, by zebra, gnu, hartebeest, and gazelle—while specific adaptations enable a still greater variety to survive. A much smaller variety of domestic stock cannot duplicate such effects. Overpopulation by domestic or wild species may upset the delicate natural balance, as may be seen by the example of elephant overpopulation in Murchison Falls (Kabalega) National Park, Uganda, and in Tsavo National Park, Kenya; whether the elephants survive or not, they have ineradicably altered the environment to the detriment of many other typical species. Animal life of particular interest
red-billed queleaMale (right) and female red-billed queleas (Quelea quelea).© Johan Swanepoel/Shutterstock.comAnimal life of particular interest to humans includes four main groups that are not mutually exclusive. They are: (1) species potentially or actually useful to humans as food (large ungulates), (2) dangerous or pest species that may have to be controlled or eliminated (locusts, tsetse flies, Quelea finches—which do immense damage to grain crops—and some ungulates or carnivores), (3) species that provide a spectacle and bring economic benefit (elephants, the larger plain ungulates, primates, or carnivores), and (4) endangered, rare, or unique species.