Elephantidae
| Noun | 1. | Elephantidae - elephants |
| 单词 | elephantidae | |||
| 释义 | Elephantidae
ElephantidaeElephantidae[el·ə′fan·tə‚dē]Elephantidae(elephants), a family of mammals of the order Proboscidea. Some taxonomists place elephants in the subfamily Elephantinae. Elephants are huge animals standing about 3.5 m tall. The trunk is massive, the neck short, and the legs columnar. The forelegs have five toes, and the hind legs four or five toes. Some toes are concealed under the skin; there is a small naillike hoof on each toe. In the course of evolution the upper lip and nose grew together to form a long movable proboscis, or trunk, ending in nostrils and one or two fingerlike processes. The trunk serves as the organ of smell, touch, and prehension. There are four grinding teeth, one on each side of the upper and lower jaws. The teeth gradually erode and are pushed out by teeth that have formed in cavities in the posterior part of the jaw. An elephant has six sets of teeth during its lifetime. Canine teeth are absent. Powerful second incisors appear only in the upper jaw, forming tusks that continue to grow throughout the animal’s life and sometimes attain great lengths. The stomach is simple. The skin is about 3 cm thick and is sparsely covered with stiff hairs. Only the extinct mammoth had a dense coat of hair. Elephants have a life expectancy of 70 to 80 years. Sexual maturity occurs at 17 to 20 years. The gestation period is 22 to 24 months; the newborn animal weighs about 90 kg and is about 1 m tall. Elephants are vegetarians, feeding on the branches, leaves, and bark of trees, on succulent rhizomes and fruits, on young bamboo shoots, and on grass. Food is usually obtained by the trunk; the tusks are used for digging food from the ground or for felling trees. Water for drinking is sucked up into the trunk and then discharged into the mouth. Elephants travel long distances, sometimes as much as 100 km a day, in search of food. They move easily through jungles and swamps, climb steep mountain slopes with little difficulty, and swim well. The animals live in herds, sometimes consisting of several dozen or hundreds of individuals. Elephants have been extensively slaughtered by man and are now protected species. The tusks are used in the manufacture of various ornaments and for industrial purposes. The meat is edible. Elephants are easily tamed and trained. Modern elephants belong to two genera: Elephas and Loxodonta. The genus Elephas has a single species, the Asiatic elephant (E. asiaticus). Males stand about 3.2 m tall, and females about 2.7 m. The animals weigh about 5 tons. The forehead is slightly concave, and the ears are small. The trunk has a single fingerlike process at the tip. The tusks of the males are well developed, each measuring about 2.5 m long and weighing about 75 kg. The females sometimes do not have tusks. The Asiatic elephant is found in wooded regions of Southeast Asia—in India, Pakistan, Burma, Thailand, Vietnam, Sri Lanka, and Sumatra. It was brought to Kalimantan (Borneo) by man. The Asiatic elephant feeds mainly on herbaceous plants. It can be easily tamed and used for a variety of tasks, mainly in forested areas. The animal can carry a load weighing as much as 600 kg on its back and can drag tree trunks weighing up to 500 kg short distances with its trunk. The genus Loxodonta consists of two species: the African bush elephant (L. africana) and the pygmy elephant (L. cyclotis). Some taxonomists consider the pygmy elephant a subspecies of the bush elephant. Male bush elephants are about 3.5 m tall, and females about 3 m. Pygmy elephants are somewhat smaller. The forehead is convex, and the ears large. The trunk has two fingerlike processes at the tip. The tusks, which are well developed in both males and females, are about 3 m long and weigh about 100 kg. The elephants inhabit the steppes, forest steppes, and forests of Africa south of the Sahara. They feed chiefly on tree branches and leaves. The animals are easily tamed in captivity but are rarely used as working animals. Elephants seem to be native to Africa, where their oldest fossil remains have been found in Upper Miocene and Lower Pliocene deposits. In the middle of the Pleistocene, elephants entered Eurasia through the Isthmus of Suez and spread almost throughout the continent. Elephants crossed over the Bering land bridge into North America at the beginning of the Pliocene. Their wide distribution and ability to adapt to a variety of climatic conditions—from tropical forests and steppes to arctic tundras—resulted in the appearance of many species and genera. The range of the animals decreased rapidly toward the end of the Pleistocene, and by the Holocene the animals had survived only in South Asia and Africa. The oldest elephants found in the USSR are known from Upper Pliocene deposits and belong to the genus Archidiskodon; they include the species A. gromovi and its descendant A. meridionalis. REFERENCESZhizn’zhivotnykh, vol. 5. Moscow, 1941.Bauer, H. Kniga o slonakh, 2nd ed. Moscow, 1964. (Translated from German.) Aguirre, E. “Evolutionary History of the Elephant.” Science, 1969, vol. 164, no. 3886. Maglio, V. J. Origin and Evolution of the Elephantidae. Philadelphia, 1973. (Transactions of the American Philosophical Society, new series, vol. 63, part 3.) V. E. GARUTT Elephantidae
Synonyms for Elephantidae
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