Tropical Fauna

Tropical Fauna 

the aggregate of animal species inhabiting the equatorial, subequatorial, and tropical zones.

Terrestrial tropical fauna is represented by inhabitants of tropical rain forests, equatorial forests, evergreen sclerophyllous tropical forests, deciduous tropical forests, savannas, deserts, and other plant communities. Despite their diverse conditions of existence, tropical animals share a number of characteristics, including thermophily and decreased fertility (the average number of eggs in bird clutches and of young in mammalian litters is smaller than among nontropical species). The number of species in tropical regions noticeably exceeds that in middle and higher latitudes. Owing to the abundance of species and the diversity of life-forms, tropical animals are characterized by highly developed protective coloration and form, in particular, mimicry. Some animals are found in extremely large numbers, for example, antelopes in the savannas, ants in tropical rain forests, and termites throughout the region.

Many taxonomic groups are entirely or predominantly tropical. In others, the number of species in the tropics is considerably higher than in the nontropics. Among mammals, monkeys are found almost exclusively in the tropics. Lemurs, elephants, rhinoceroses, tapir, pangolins, anteaters, and sloths are limited to only a few tropical regions. A large number of bat species occur in the tropics; however, those found exclusively in the tropics are the Old World fruit bats and the leaf-nosed bats of the Americas.

Characteristic birds are parrots, doves, cuckoos, trogons, bar-bets, hornbills, toucans, sunbirds, honey eaters, and hummingbirds. Typical reptiles include iguanas (North and South America, Madagascar, Fiji), geckos, skinks, chameleons (mainly in Africa), snakes, and crocodiles. Commonly encountered amphibians include true frogs, tree frogs, toads, and caecilians. There are numerous species of invertebrates, including scorpions, spiders, various insects (beetles, butterflies, orthopterans, sand flies, ants, termites), and terrestrial leeches. The tsetse fly, which transmits the causative agent of sleeping sickness in man and of nagana in cattle, occurs in tropical Africa.

The tropical fauna of the ocean is distinguished for its great diversity of forms, but it includes considerably smaller numbers of certain species than in other climatic zones (except for littoral species off tropical islands). Among animals found only or chiefly in the tropics are certain fishes (sharks, rays, flying fishes, plec-tognaths, swordfishes, and sailfishes), sea turtles, sea snakes, and certain invertebrates (pteropods, pearl oysters, nautiluses, sto-matopods, spiny lobsters, and reef-forming corals). Also associated with tropical seas are the tropic bird (Phaëthon) and frigate bird, which spend the greater part of their lives hunting for food over the sea. Dugongs and manatees inhabit tropical seas, and the sperm whale reproduces in tropical seas.

The tropical fauna of land and ocean is represented by the most ancient forms, since its development was not interrupted by the continental glaciers characteristic of temperate and frigid zones and the decreased water temperatures associated with the glaciers. Under the influence of man, the terrestrial tropical fauna has undergone significant changes. Many species have been eradicated or are on the brink of extinction; the fauna of the tropical islands has suffered especially. Synanthropic animals (mice, rats) are widely distributed in the tropics. The protection of tropical fauna is important for the preservation of the gene pool, which plays a large role in the domestication and acclimatization of animals.

REFERENCES

Vtorov, P. P., and N. N. Drozdov. Biogeografiia materikov. Moscow, 1974.
Wallace, A. R. Tropicheskaia priroda, 3rd ed. Moscow, 1975. (Translated from English.)
Briggs, J. C. Marine Zoogeography. New York, 1974.

A. G. VORONOV