Proboscidea is an order including only one family, Elephantidae or the elephants, with 3 species: the Savannah Elephant, the Forest Elephant and the Asian Elephant (formerly known as the Indian Elephant). During the period of the ice age there were more, now extinct species, including the elephant-like mammoth and mastodont and the "shovel tuskers", the platybelodon and amebelodon.
Elephants are the largest living land mammals. At birth it is common for an elephant calf to weigh 100 kg (225 pounds). It takes 20 to 22 months for a baby elephant to develop, the longest gestation period of any land animal. The largest elephant ever recorded was a male shot in Angola in 1974, that weighed 12 tonnes (13.5 tons).
An elephant's most obvious characteristic is the trunk, a much elongated combination of nose and upper lip, which can be used to grab objects such as food. Elephants also have tusks, large teeth coming out of their upper jaws. Elephant tusks are the major source of ivory, but because of the increased rarity of elephants, hunting and ivory trade is now illegal.
Elephants have three premolars and three molars in each quadrant. They erupt in order from front to back, then wear down as the elephant chews its highly fibrous diet. When the last molar has worn out, the elephant typically dies of malnutrition; elephants in captivity can be kept alive longer than that by feeding them preground food. The molars of the African elephant are loxodont, hence the genus name.
Elephants are vegetarians, spending 16 hours a day collecting plant food from all levels. Their diet is at least 50% grasses, supplemented with leaves, twigs, bark, roots, and small amounts of fruits, seeds and flowers. Because elephants only use 40% of what they eat they have to make up for their digestive system's lack of efficiency in volume. An adult elephant can consume 300 to 600 pounds of food a day. 60% of that food leaves the elephant's body undigested.
Walking at a normal pace an elephant covers about 2 to 4 miles an hour but they can reach 24 miles an hour at full speed.
It has long been known that African and Asian elephants were separate species. African elephants tend to be larger than the Asian species (up to 4m high and 7500kg) and have bigger ears (which are rich in veins and thought to help in cooling off the blood in the hotter African climate). Female African elephants have tusks, while female Asian Elephants do not. African elephants have a dipped back, as compared with the Asian species, and have two "fingers" at the tip of their trunks, as opposed to only one.
There are two populations of African elephants, savanna and forest, and recent genetic studies have led to a reclassification of these as separate species, the forest population now being called Loxodonta cyclotis, and the savanna or bush population termed Loxodonta africanus. This reclassification has important implications for conservation, because it means where there were thought to be two small populations of a single endangered species, there may in fact be two separate species, each of which is even more severely endangered. There's also a potential danger in that if the forest elephant isn't explicitly listed as an endangered species, poachers and smugglers might thus be able to evade the law forbidding trade in endangered animals and their body parts.
Poaching has had some unexpected consequences on elephant anatomy as well. African ivory hunters, by killing only tusked elephants, have given a much larger chance of mating to elephants with small tusks or no tusks at all. The propagation of the absent-tusk gene has resulted in the birth of large numbers of tuskless elephants, now approaching 30% in some populations (compare with a rate of about 1% in 1930). Tusklessness, once a very rare genetic abnormality, has become a widespread hereditary trait. It is possible, if unlikely, that continued poaching could bring about a complete absence of tusks in African elephants, a development normally requiring thousands of years of evolution. The effect of tuskless elephants on the environment, and on the elephants themselves, could be dramatic. Elephants use their tusks to root around in the ground for necessary minerals, tear apart vegetation, and spar with one another for mating rights.
Elephants have been used in various capacities by humans. War elephants
were used by armies in the Indian sub-continent, and by the Persian empire.
This use was adopted by Hellenistic Ptolemaic and Seleucid kingdoms. The
Carthaginian general Hannibal took elephants across the Alps when he was
fighting the Romans. Hannibal brought too few elephants to be of much
military use, although his horse cavalry was quite successful. Hannibal
probably used a now extinct third African species, the North African elephant,
smaller than its two southern cousins.
Elephant footprints (tyre tracks for scale)
Elephants have been used for transportation and entertainment, and are common to circuses around the world. Throughout Siam, India, and most of South Asia they were used in the military, used for heavy labor, especially for uprooting trees and moving logs, and were also commonly used as executioners to crush the condemned underfoot.
However, elephants have never been truly domesticated: the male elephant in heat is dangerous and difficult to control; elephants used by humans have typically been female. War elephants were an exception, however, as female elephants in battle will run from a male, only males could be used in war.
In the wild, elephants exhibit complex social behavior and strong family bonds. Most females will stay with their original natal group for a lifetime. Social hierarchy in calf-cow groups is based on size and age, with the largest and oldest females at the top and the smallest and youngest coming in last. Adolescent males determine their own ranking order through head-butting contests, where strength and temperament are as important as size and age. They communicate with very low and long-ranging subsonic tones.
A recent theory holds that elephants, which share an ancestor with sea cows, evolved from animals which spent most of their time in the water or even under water, using their trunks like snorkels for breathing. It has been recently discovered that the species can still swim using their trunks in that manner.
Elephants in pop culture
* Jumbo, a circus elephant, has been immortalized as a word for large.
Elephants in politics
The elephant is also the symbol for the United States Republican Party (often pictured with the Democratic party's donkey). The first depiction of the Republican party appeared in a cartoon by Thomas Nast of Harper's Weekly in 1874.
Elephants in religion
* A white elephant is considered holy in Thailand.