Elephant Pond

Elephants are the largest existing land animals. Three living species are currently recognised: the African bush elephant, the African forest elephant, and the Asian elephant. They are the only surviving members of the family Elephantidae and the order Proboscidea. The order was formerly much more diverse during the Pleistocene, but most species became extinct during the Late Pleistocene epoch. Distinctive features of elephants include a long proboscis called a trunk, tusks, large ear flaps, pillar-like legs, and tough but sensitive skin. The trunk is used for breathing, bringing food and water to the mouth, and grasping objects. Tusks, which are derived from the incisor teeth, serve both as weapons and as tools for moving objects and digging. The large ear flaps assist in maintaining a constant body temperature as well as in communication. African elephants have larger ears and concave backs, whereas Asian elephants have smaller ears, and convex or level backs.

Elephants are scattered throughout sub-Saharan Africa, South Asia, and Southeast Asia and are found in different habitats, including savannahs, forests, deserts, and marshes. They are herbivorous, and they stay near water when it is accessible. They are considered to be keystone species, due to their impact on their environments. Elephants have a fission–fusion society, in which multiple family groups come together to socialise. 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, which do not include bulls, are usually led by the oldest cow, known as the matriarch.

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. They enter a state of increased testosterone and aggression known as musth, which helps them gain dominance over other males as well as 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 appear to show empathy for dying and dead family members.

African bush elephants and Asian elephants are listed as endangered and African forest elephants as Critically Endangered by the International Union for Conservation of Nature (IUCN). 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.

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).

Taxonomy

Alongside their closest relatives belong to the family Elephantidae, the sole remaining family within the order Proboscidea. Their closest extant relatives are the sirenians (dugongs and manatees) and the hyraxes, with which they share the clade Paenungulata within the superorder Afrotheria. Elephants and sirenians are further grouped in the clade Tethytheria.

Three species of elephants are recognised; the African bush elephant ('' Loxodonta africana'') and forest elephant (''Loxodonta cyclotis'') of sub-Saharan Africa, and the Asian elephant (''Elephas maximus'') of South and Southeast Asia. African elephants have larger ears, a concave back, more wrinkled skin, a sloping abdomen, and two finger-like extensions at the tip of the trunk. Asian elephants have smaller ears, a convex or level back, smoother skin, a horizontal abdomen that occasionally sags in the middle and one extension at the tip of the trunk. The looped ridges on the molars are narrower in the Asian elephant while those of the African are more diamond-shaped. The Asian elephant also has dorsal bumps on its head and some patches of depigmentation on its skin.Shoshani, pp. 38–41.

Among African elephants, forest elephants have smaller and more rounded ears and thinner and straighter tusks than bush elephants and are limited in range to the forested areas of western and Central Africa. Both were traditionally considered a single species, ''Loxodonta africana'', but molecular studies have affirmed their status as separate species. In 2017, DNA sequence analysis showed that ''L. cyclotis'' is more closely related to the extinct ''Palaeoloxodon antiquus'', than it is to ''L. africana,'' possibly undermining the genus ''Loxodonta'' as a whole.

Evolution and extinct relatives

Over 180 extinct members and three major evolutionary radiations of the order Proboscidea have been recorded. The earliest proboscids, the African '' Eritherium'' and '' Phosphatherium'' of the late Paleocene, heralded the first radiation. The Eocene included ''Numidotherium'', ''Moeritherium,'' and ''Barytherium'' from Africa. These animals were relatively small and aquatic. Later on, genera such as ''Phiomia'' and ''Palaeomastodon'' arose; the latter likely inhabited forests and open woodlands. Proboscidean diversity declined during the Oligocene. One notable species of this epoch was ''Eritreum melakeghebrekristosi'' of the Horn of Africa, which may have been an ancestor to several later species. The beginning of the Miocene saw the second diversification, with the appearance of the deinotheres and the mammutids. The former were related to ''Barytherium'' and lived in Africa and Eurasia,Sukumar, pp. 16–19. while the latter may have descended from ''Eritreum'' and spread to North America.

The second radiation was represented by the emergence of the gomphotheres in the Miocene, which likely evolved from ''Eritreum'' and originated in Africa, spreading to every continent except Australia and Antarctica. Members of this group included ''Gomphotherium'' and ''Platybelodon''. The third radiation started in the late Miocene and led to the arrival of the elephantids, which descended from, and slowly replaced, the gomphotheres. The African ''Primelephas gomphotheroides'' gave rise to ''Loxodonta'', ''Mammuthus,'' and ''Elephas''. ''Loxodonta'' branched off earliest around the Miocene and Pliocene

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