Elephants are large mammals of the family Elephantidae and the order Proboscidea. Three species are currently recognized: the African bush elephant (Loxodonta africana), the African forest elephant (L. cyclotis), and the Asian elephant (Elephas maximus). Elephants are scattered throughout sub-Saharan Africa, South Asia, and Southeast Asia. Elephantidae is the only surviving family of the order Proboscidea; other, now extinct, members of the order include deinotheres, gomphotheres, mammoths, and mastodons.
All elephants have several distinctive features, the most notable of which is a long trunk or proboscis, used for many purposes, particularly breathing, lifting water, and grasping objects. Their incisors grow into tusks, which can serve as weapons and as tools for moving objects and digging. Elephants' large ear flaps help to control their body temperature. Their pillar-like legs can carry their great weight. African elephants have larger ears and concave backs while Asian elephants have smaller ears and convex or level backs.
Elephants are herbivorous and can be found in different habitats including savannahs, forests, deserts, and marshes. They prefer to stay near water. They are considered to be keystone species due to their impact on their environments. Other animals tend to keep their distance from elephants while predators, such as lions, tigers, hyenas, and any wild dogs, usually target only young elephants (or "calves"). Females ("cows") tend to live in family groups, which can consist of one female with her calves or several related females with offspring. The groups are led by an individual known as the matriarch, often the oldest cow.
Elephants have a fission–fusion society in which multiple family groups come together to socialise. Males ("bulls") leave their family groups when they reach puberty and may live alone or with other males. Adult bulls mostly interact with family groups when looking for a mate and enter a state of increased testosterone and aggression known as musth, which helps them gain dominance and reproductive success. Calves are the centre of attention in their family groups and rely on their mothers for as long as three years. Elephants can live up to 70 years in the wild. They communicate by touch, sight, smell, and sound; elephants use infrasound, and seismic communication over long distances. Elephant intelligence has been compared with that of primates and cetaceans. They appear to have self-awareness and show empathy for dying or dead individuals of their kind.
African elephants are listed as vulnerable by the International Union for Conservation of Nature (IUCN) while the Asian elephant is classed as endangered. One of the biggest threats to elephant populations is the ivory trade, as the animals are poached for their ivory tusks. Other threats to wild elephants include habitat destruction and conflicts with local people. Elephants are used as working animals in Asia. In the past, they were used in war; today, they are often controversially put on display in zoos, or exploited for entertainment in circuses. Elephants are highly recognisable and have been featured in art, folklore, religion, literature, and popular culture.
| Scientific classification | |
|---|---|
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Subphylum: | Vertebrata |
| Class: | Mammalia |
| Superorder: | Afrotheria |
| Order: | Proboscidea |
| Family: | Elephantidae Gray, 1821 |
| Genera | |
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Etymology
The word "elephant" is based on the Latin elephas (genitive elephantis) ("elephant"), which is the Latinised form of the Greek ἐλέφας (elephas) (genitive ἐλέφαντος (elephantos)), probably from a non-Indo-European language, likely Phoenician. It is attested in Mycenaean Greek as e-re-pa (genitive e-re-pa-to) in Linear B syllabic script. As in Mycenaean Greek, Homer used the Greek word to mean ivory, but after the time of Herodotus, it also referred to the animal. The word "elephant" appears in Middle English as olyfaunt (c.1300) and was borrowed from Old French oliphant (12th century). Loxodonta, the generic name for the African elephants, is Greek for "oblique-sided tooth".Behaviour and life history
Ecology and activities
The African bush elephant can be found in habitats as diverse as dry savannahs, deserts, marshes, and lake shores, and in elevations from sea level to mountain areas above the snow line. Forest elephants mainly live in equatorial forests but will enter gallery forests and ecotones between forests and savannahs. Asian elephants prefer areas with a mix of grasses, low woody plants, and trees, primarily inhabiting dry thorn-scrub forests in southern India and Sri Lanka and evergreen forests in Malaya. Elephants are herbivorous and will eat leaves, twigs, fruit, bark, grass and roots. They are born with sterile intestines and require bacteria obtained from their mother's feces to digest vegetation. African elephants are mostly browsers while Asian elephants are mainly grazers. They can consume as much as 150 kg (330 lb) of food and 40 L (11 US gal) of water in a day. Elephants tend to stay near water sources.Major feeding bouts take place in the morning, afternoon and night. At midday, elephants rest under trees and may doze off while standing. Sleeping occurs at night while the animal is lying down. Elephants average 3–4 hours of sleep per day. Both males and family groups typically move 10–20 km (6–12 mi) a day, but distances as far as 90–180 km (56–112 mi) have been recorded in the Etosha region of Namibia. Elephants go on seasonal migrations in search of food, water, minerals, and mates. At Chobe National Park, Botswana, herds travel 325 km (202 mi) to visit the river when the local waterholes dry up.
Because of their large size, elephants have a huge impact on their environments and are considered keystone species. Their habit of uprooting trees and undergrowth can transform savannah into grasslands; when they dig for water during drought, they create waterholes that can be used by other animals. They can enlarge waterholes when they bathe and wallow in them. At Mount Elgon, elephants excavate caves that are used by ungulates, hyraxes, bats, birds and insects. Elephants are important seed dispersers; African forest elephants ingest and defecate seeds, with either no effect or a positive effect on germination. The seeds are typically dispersed in large amounts over great distances. In Asian forests, large seeds require giant herbivores like elephants and rhinoceros for transport and dispersal. This ecological niche cannot be filled by the next largest herbivore, the tapir. Because most of the food elephants eat goes undigested, their dung can provide food for other animals, such as dung beetles and monkeys. Elephants can have a negative impact on ecosystems. At Murchison Falls National Park in Uganda, the overabundance of elephants has threatened several species of small birds that depend on woodlands. Their weight can compact the soil, which causes the rain to run off, leading to erosion.
Elephants typically coexist peacefully with other herbivores, which will usually stay out of their way. Some aggressive interactions between elephants and rhinoceros have been recorded. At Aberdare National Park, Kenya, a rhino attacked an elephant calf and was killed by the other elephants in the group. At Hluhluwe–Umfolozi Game Reserve, South Africa, introduced young orphan elephants went on a killing spree that claimed the lives of 36 rhinos during the 1990s, but ended with the introduction of older males. The size of adult elephants makes them nearly invulnerable to predators, though there are rare reports of adult elephants falling prey to tigers. Calves may be preyed on by lions, spotted hyenas, and wild dogs in Africa and tigers in Asia. The lions of Savuti, Botswana, have adapted to hunting juvenile elephants during the dry season, and a pride of 30 lions has been recorded killing juvenile individuals between the ages of four and eleven years. Elephants appear to distinguish between the growls of larger predators like tigers and smaller ones like leopards (which have not been recorded killing calves); the latter they react less fearfully and more aggressively to. Elephants tend to have high numbers of parasites, particularly nematodes, compared to other herbivores. This is due to lower predation pressures that would otherwise kill off many of the individuals with significant parasite loads.
Social organisation
Female elephants spend their entire lives in tight-knit matrilineal family groups, some of which are made up of more than ten members, including three pairs of mothers with offspring, and are led by the matriarch which is often the eldest female. She remains leader of the group until death or if she no longer has the energy for the role; a study on zoo elephants showed that when the matriarch died, the levels of faecal corticosterone ('stress hormone') dramatically increased in the surviving elephants. When her tenure is over, the matriarch's eldest daughter takes her place; this occurs even if her sister is present. The older matriarchs tend to be more effective decision-makers.The social circle of the female elephant does not necessarily end with the small family unit. In the case of elephants in Amboseli National Park, Kenya, a female's life involves interaction with other families, clans, and subpopulations. Families may associate and bond with each other, forming what are known as bond groups. These are typically made of two family groups, which may be closely related due to previously being part of the same family group which split after becoming too large for the available resources. During the dry season, elephant families may cluster together and form another level of social organisation known as the clan. Groups within these clans do not form strong bonds, but they defend their dry-season ranges against other clans. There are typically nine groups in a clan. The Amboseli elephant population is further divided into the "central" and "peripheral" subpopulations.
Some elephant populations in India and Sri Lanka have similar basic social organisations. There appear to be cohesive family units and loose aggregations. They have been observed to have "nursing units" and "juvenile-care units". In southern India, elephant populations may contain family groups, bond groups and possibly clans. Family groups tend to be small, consisting of one or two adult females and their offspring. A group containing more than two adult females plus offspring is known as a "joint family". Malay elephant populations have even smaller family units, and do not have any social organisation higher than a family or bond group. Groups of African forest elephants typically consist of one adult female with one to three offspring. These groups appear to interact with each other, especially at forest clearings.
The social life of the adult male is very different. As he matures, a male spends more time at the edge of his group and associates with outside males or even other families. At Amboseli, young males spend over 80% of their time away from their families when they are 14–15. When males permanently leave, they either live alone or with other males. The former is typical of bulls in dense forests. Asian males are usually solitary, but occasionally form groups of two or more individuals; the largest consisted of seven bulls. Larger bull groups consisting of over 10 members occur only among African bush elephants, the largest of which numbered up to 144 individuals. These elephants can be quite sociable when not competing for dominance or mates, and will form long-term relationships. A dominance hierarchy exists among males, whether they range socially or solitarily. Dominance depends on the age, size and sexual condition, and when in groups, males follow the lead of the dominant bull. Young bulls may seek out the company and leadership of older, more experienced males, whose presence appears to control their aggression and prevent them from exhibiting "deviant" behaviour. Adult males and females come together for reproduction. Bulls associate with family groups if an oestrous cow is present.
