Elephant is the common name for any of the large land mammals comprising the family Elephantidae in the order Proboscidea, characterized by thick skin, tusks, large pillar-like legs, large flapping ears, and a proboscis, or flexible trunk, that is a fusion of the nose and upper lip. There are only three living species (two in traditional classifications), but many other species are found in the fossil record, appearing in the Pliocene over 1.8 million years ago and having become extinct since the last ice age, which ended about 10,000 years ago. The mammoths are the best known of these.
The three living species of elephants are the African bush elephant or savanna elephant (Loxodonta africana), the African forest elephant (Loxodonta cyclotis), and the Asian elephant (Elephas maximus, also known as the Indian elephant). However, traditionally, and in some present day taxonomies, only one species of African elephant (Loxodonta africana) is recognized, with two subspecies (L. a. africana and L. a. cyclotis), and some taxonomies recognize three species of African elephant.
Elephants are the largest land animals today. Some fossil species, however, were smaller, with the smallest about the size of a large pig.
While advancing their own individual function of survival as a species, elephants also provide a larger function for the ecosystem and for humans. Ecologically, they are key animals in their environment, clearing areas for the growth of young trees, making trails, releasing sources of underground water during the dry season, and so forth. For humans, partially domesticated elephants have been used for labor and warfare for centuries and traditionally were a source of ivory. These massive exotic animals have long been a source of wonder for humans, who feature them prominently in culture and view them in zoos and wildlife parks.
However, the relationship between elephants and humans is a conflicted one, as anthropogenic factors such as hunting and habitat change have been major factors in risks to survival of elephants, the treatment in zoos and circuses has been highly criticized, and elephants have often attacked human beings when their habitats intersect.
OverviewComparative view of the human and elephant frames, c. 1860.
Elephants comprise the family Elephantidae within the order Proboscidea. Proboscidea includes other elephant-like families, notably the Mammutidae, whose members are known as mastodons or mastodonts. Like members of Elephantidae, mastodons have long tusks, large pillar-like legs, and a flexible trunk or probosis. However, mastodons have molar teeth of a different structure. All proboscidians are extinct with the exception of the three extant species within Elephantidae. Altogether, paleontologists have identified about 170 fossil species that are classified as belonging to the Proboscidea, with the oldest dating from the early Paleocene epoch of the Paleogene period over 56 million years ago.
The mammoths, which comprise the genus Mammuthus, are another extinct group that overlapped in time with the mastodons. However, they also belonged to the Elephantidae family, and thus are true elephants. Unlike the generally straight tusks of modern elephants, mammoth tusks typically were curved upward, sometimes strongly curved and spirally twisted, and were long. In northern species, there also was a covering of long hair. As members of Elephantidae, they are close relatives of modern elephants and in particular the Asian elephant (Elephas maximus). They lived from the Pliocene epoch, about four million years ago to around 4,500 years ago.
Elephants once were classified along with other thick skinned animals in a now invalid order, Pachydermata. Primelephas, the ancestor of mammoths and modern elephants, appeared in the late Miocene epoch, about seven million years ago.Comparative anatomy of head and forepart of the body of the Asian Elephant (Elephas maximus, 1) and the African Elephant (Loxodonta africana, 2).
Among modern-day elephants, those of the genus Loxodonta, known collectively as African elephants, are currently found in 37 countries in Africa. This genus contains two (or, arguably, three, and traditionally one) living species, with the two commonly recognized species L. africana, known as the African bush elephant, and Loxodonta cyclotis, known as the African forest elephant. On the other hand, the Asian elephant species, Elephas maximus, is the only surviving member of its genus, but can be divided into four subspecies.
African elephants are distinguished from Asian elephants in several ways, the most noticeable being their ears, which are much larger. The African elephant is typically larger than the Asian elephant and has a concave back. Both African males and females have external tusks and are usually less hairy than their Asian cousins. Typically, only the males of the Asian elephant have large external tusks, while both tusks of African elephants are large. African elephants are the largest land animals (NG).
The elephant's gestation period is 22 months, the longest of any land animal. At birth, it is common for an elephant calf to weigh 120 kilograms (260 pounds). They typically live for 50 to 70 years, but the oldest recorded elephant lived for 82 years (AC).
The largest elephant ever recorded was shot in Angola in 1956. This male weighed about 12,000 kilograms (26,000 pounds) (Sanparks), with a shoulder height of 4.2 meters (14 feet), a meter (yard) taller than the average male African elephant (SDZ 2009). The smallest elephants, about the size of a calf or a large pig, were a prehistoric species that lived on the island of Crete during the Pleistocene epoch (Bate 1907).
The elephant has appeared in cultures across the world. They are a symbol of wisdom in Asian cultures and are famed for their memory and intelligence, where they are thought to be on par with cetaceans (DC 1999), and even placed in the category of the great apes in terms of cognitive abilities for tool use and manufacture (Hart et al. 2001). Aristotle once said the elephant was "the beast which passeth all others in wit and mind" (O'Connell 2007).
Healthy adult elephants have no natural predators (Joubert 2006), although lions may take calves or weak individuals (Loveridge et al. 2006). They are, however, increasingly threatened by human intrusion and poaching. Once numbering in the millions, the African elephant population has dwindled to between 470,000 and 690,000 individuals (WWF 2009). The world population of Asian elephants, also called Indian elephants, is estimated to be around 60,000, about a tenth of the number of African elephants. More precisely, it is estimated that there are between 38,000 and 53,000 wild elephants and between 14,500 and 15,300 domesticated elephants in Asia with perhaps another 1,000 scattered around zoos in the rest of the world (EleAid). The Asian elephants' decline has possibly been more gradual than the African and caused primarily by poaching and habitat destruction by human encroachment.
While the elephant is a protected species worldwide, with restrictions in place on capture, domestic use, and trade in products such as ivory, CITES reopening of "one time" ivory stock sales, has resulted in increased poaching. Certain African nations report a decrease of their elephant populations by as much as two-thirds, and populations in certain protected areas are in danger of being eliminated (Eichenseher 2008). Since poaching has increased by as much as 45%, the actual population is unknown (Gavshon 2008).
The word "elephant" has its origins in the Greek ἐλέφας, meaning "ivory" or "elephant" (Soanes and Stevenson 2006). It also has been reported that the word elephant comes via the Latin ele and phant, meaning "huge arch" (AC).
TrunkAn elephant can use its trunk for a variety of purposes. This one is wiping its eye.Eyes of an Asian elephant.
The proboscis, or trunk, is a fusion of the nose and upper lip, elongated and specialized to become the elephant's most important and versatile appendage. African elephants are equipped with two fingerlike projections at the tip of their trunk, while Asians have only one. According to biologists, the elephant's trunk may have over forty thousand individual muscles in it (Frey), making it sensitive enough to pick up a single blade of grass, yet strong enough to rip the branches off a tree. Some sources indicate that the correct number of muscles in an elephant's trunk is closer to one hundred thousand (MacKenzie 2001)
Most herbivores (plant eaters, like the elephant) possess teeth adapted for cutting and tearing off plant materials. However, except for the very young or infirm, elephants always use their trunks to tear up their food and then place it in their mouth. They will graze on grass or reach up into trees to grasp leaves, fruit, or entire branches. If the desired food item is too high up, the elephant will wrap its trunk around the tree or branch and shake its food loose or sometimes simply knock the tree down altogether.
The trunk is also used for drinking. Elephants suck water up into the trunk (up to fifteen quarts or fourteen liters at a time) and then blow it into their mouth. Elephants also inhale water to spray on their body during bathing. On top of this watery coating, the animal will then spray dirt and mud, which act as a protective sunscreen. When swimming, the trunk makes an excellent snorkel (West 2001; West et al. 2003).
This appendage also plays a key role in many social interactions. Familiar elephants will greet each other by entwining their trunks, much like a handshake. They also use them while play-wrestling, caressing during courtship and mother/child interactions, and for dominance displays: a raised trunk can be a warning or threat, while a lowered trunk can be a sign of submission. Elephants can defend themselves very well by flailing their trunk at unwanted intruders or by grasping and flinging them.
An elephant also relies on its trunk for its highly developed sense of smell. Raising the trunk up in the air and swiveling it from side to side, like a periscope, it can determine the location of friends, enemies, and food sources.
TusksTrunks of African and Asian elephants.
The tusks of an elephant are its second upper incisors. Tusks grow continuously; an adult male's tusks will grow about 18 cm (7 in) a year. Tusks are used to dig for water, salt, and roots; to debark trees, to eat the bark; to dig into baobab trees to get at the pulp inside; and to move trees and branches when clearing a path. In addition, they are used for marking trees to establish territory and occasionally as weapons.
Both male and female African elephants have large tusks that can reach over 3 meters (10 feet) in length and weigh over 90 kilograms (200 pounds). In the Asian species, only the males have large tusks. Female Asians have tusks that are very small or absent altogether. Asian males can have tusks as long as the much larger Africans, but they are usually much slimmer and lighter; the heaviest recorded is 39 kilograms (86 pounds).
The tusk of both species is mostly made of calcium phosphate in the form of apatite. As a piece of living tissue, it is relatively soft (compared with other minerals such as rock), and the tusk, also known as ivory, is strongly favored by artists for its carvability. The desire for elephant ivory has been one of the major factors in the reduction of the world's elephant population.
Like humans who are typically right- or left-handed, elephants are usually right- or left-tusked. The dominant tusk, called the master tusk, is generally shorter and more rounded at the tip from wear.
Some extinct relatives of elephants had tusks in their lower jaws in addition to their upper jaws, such as Gomphotherium, or only in their lower jaws, such as Deinotherium. Tusks in the lower jaw are also second incisors. These grew out large in Deinotherium and some mastodons, but in modern elephants they disappear early without erupting.
Elephants' teeth are very different from those of most other mammals. Over their lives they usually have 28 teeth. These are:
- The two upper second incisors: these are the tusks
- The milk precursors of the tusks
- 12 premolars, 3 in each side of each jaw (upper and lower)
- 12 molars, 3 in each side of each jaw
This gives elephants a dental formula of:
As noted above, in modern elephants the second incisors in the lower jaw disappear early without erupting, but became tusks in some forms now extinct.
Unlike most mammals, which grow baby teeth and then replace them with a permanent set of adult teeth, elephants have cycles of tooth rotation throughout their entire life. The tusks have milk precursors, which fall out quickly and the adult tusks are in place by one year of age, but the molars are replaced five times in an average elephant's lifetime (IZ 2008). The teeth do not emerge from the jaws vertically like with human teeth. Instead, they move horizontally, like a conveyor belt. New teeth grow in at the back of the mouth, pushing older teeth toward the front, where they wear down with use and the remains fall out.
When an elephant becomes very old, the last set of teeth is worn to stumps, and it must rely on softer foods to chew. Very elderly elephants often spend their last years exclusively in marshy areas where they can feed on soft wet grasses. Eventually, when the last teeth fall out, the elephant will be unable to eat and will die of starvation. Were it not for tooth wear out, the metabolism of elephants likely would allow them to live much longer. However, as more habitat is destroyed, the elephants' living space becomes smaller and smaller; the elderly no longer have the opportunity to roam in search of more appropriate food and will, consequently, die of starvation at an earlier age.
SkinSkin of an African (left) and Asian (right) elephant.
Elephants are colloquially called pachyderms (from their original scientific classification), which means thick-skinned animals. An elephant's skin is extremely tough around most parts of its body and measures about 2.5 centimeters (1.0 inch) thick. However, the skin around the mouth and inside of the ear is paper-thin.
Normally, the skin of an Asian elephant is covered with more hair than its African counterpart. This is most noticeable in the young. Asian calves are usually covered with a thick coat of brownish red fuzz. As they get older, this hair darkens and becomes more sparse, but it will always remain on their heads and tails.
The various species of elephants are typically grayish in color, but the African elephants very often appear brown or reddish from wallowing in mud holes of colored soil.
Wallowing is an important behavior in elephant society. Not only is it important for socialization, but the mud acts as a sunscreen, protecting their skin from harsh ultraviolet radiation. Although tough, an elephant's skin is very sensitive. Without regular mud baths to protect it from burning, as well as from insect bites and moisture loss, an elephant's skin would suffer serious damage. After bathing, the elephant will usually use its trunk to blow dirt on its body to help dry and bake on its new protective coat. As elephants are limited to smaller and smaller areas, there is less water available, and local herds will often come too close in the search to use these limited resources.
Wallowing also aids the skin in regulating body temperatures. Elephants have difficulty in releasing heat through the skin because, in proportion to their body size, they have very little surface area relative to volume. The ratio of an elephant's mass to the surface area of its skin is many times that of a human. Elephants have even been observed lifting up their legs to expose the soles of their feet, presumably in an effort to expose more skin to the air. Since wild elephants live in very hot climates, they must have other means of getting rid of excess heat.
Legs and feetElephant using its feet to crush a watermelon prior to eating it
An elephant's legs are great straight pillars, as they must be to support its bulk. The elephant needs less muscular power to stand because of its straight legs and large pad-like feet. For this reason, an elephant can stand for very long periods of time without tiring. In fact, African elephants rarely lie down unless they are sick or wounded. Indian elephants, in contrast, lie down frequently.
The feet of an elephant are nearly round. African elephants have three nails on each hind foot, and four on each front foot. Indian elephants have four nails on each hind foot and five on each front foot. Beneath the bones of the foot is a tough, gelatinous material that acts as a cushion or shock absorber. Under the elephant's weight the foot swells, but it gets smaller when the weight is removed. An elephant can sink deep into mud, but can pull its legs out more readily because its feet become smaller when they are lifted.
An elephant is a good swimmer, but it can not trot, jump, nor gallop. It does have two gaits: a walk; and a faster gait that is similar to running.
In walking, the legs act as pendulums, with the hips and shoulders rising and falling while the foot is planted on the ground. With no "aerial phase," the faster gait does not meet all the criteria of running, as elephants always have at least one foot on the ground. However, an elephant moving fast uses its legs much like a running animal, with the hips and shoulders falling and then rising while the feet are on the ground. In this gait, an elephant will have three feet off the ground at one time. As both of the hind feet and both of the front feet are off the ground at the same time, this gait has been likened to the hind legs and the front legs taking turns running (Moore 2007).
Although they start this "run" at only 8 kilomters per hour (Ren and Hutchinson 2007), elephants can reach speeds up to 40 kilometers per hour (25 mph) (Famini and Hutchinson 2003), all the while using the same gait. At this speed, most other four-legged creatures are well into a gallop, even accounting for leg length. Spring-like kinetics could explain the difference between the motion of elephants and other animals (Hutchinson et al. 2003).
EarsDifference between Asian (left) and African (right) elephant ears.
The large flapping ears of an elephant are also very important for temperature regulation. Elephant ears are made of a very thin layer of skin stretched over cartilage and a rich network of blood vessels. On hot days, elephants will flap their ears constantly, creating a slight breeze. This breeze cools the surface blood vessels, and then the cooler blood gets circulated to the rest of the animal's body. The hot blood entering the ears can be cooled as much as ten degrees Fahrenheit before returning to the body.
Differences in the ear sizes of African and Asian elephants can be explained, in part, by their geographical distribution. Africans originated and stayed near the equator, where it is warmer. Therefore, they have bigger ears. Asians live farther north, in slightly cooler climates, and thus have smaller ears.
The ears are also used in certain displays of aggression and during the males' mating period. If an elephant wants to intimidate a predator or rival, it will spread its ears out wide to make itself look more massive and imposing. During the breeding season, males give off an odor from the musth gland located behind their eyes. Poole (1989) has theorized that the males will fan their ears in an effort to help propel this "elephant cologne" great distances.
Behavior, senses, and reproduction
Social behaviorElephant footprints (tire tracks for scale)
Elephants live in a structured social order. The social lives of male and female elephants are very different. The females spend their entire lives in tightly knit family groups made up of mothers, daughters, sisters, and aunts. These groups are led by the eldest female, or matriarch. Adult males, on the other hand, live mostly solitary lives.
The social circle of the female elephant does not end with the small family unit. In addition to encountering the local males that live on the fringes of one or more groups, the female's life also involves interaction with other families, clans, and subpopulations. Most immediate family groups range from five to fifteen adults, as well as a number of immature males and females. When a group gets too big, a few of the elder daughters will break off and form their own small group. They remain very aware of which local herds are relatives and which are not.
The life of the adult male is very different. As he gets older, he begins to spend more time at the edge of the herd, gradually going off on his own for hours or days at a time. Eventually, days become weeks, and somewhere around the age of fourteen, the mature male, or bull, sets out from his natal group for good. While males do live primarily solitary lives, they will occasionally form loose associations with other males. These groups are called bachelor herds. The males spend much more time than the females fighting for dominance with each other. Only the most dominant males will be permitted to breed with cycling females. The less dominant ones must wait their turn. It is usually the older bulls, forty to fifty years old, that do most of the breeding.
The dominance battles between males can look very fierce, but typically they inflict very little injury. Most of the bouts are in the form of aggressive displays and bluffs. Ordinarily, the smaller, younger, and less confident animal will back off before any real damage can be done. However, during the breeding season, the battles can get extremely aggressive, and the occasional elephant is injured. During this season, known as musth, a bull will fight with almost any other male it encounters, and it will spend most of its time hovering around the female herds, trying to find a receptive mate.
"Rogue elephant" is a term for a lone, violently aggressive wild elephant.
With a mass just over 5 kilograms (11 pounds), elephant brains are larger than those of any other land animal, and although the largest whales have body masses twenty-fold those of a typical elephant, whale brains are barely twice the mass of an elephant's.
A wide variety of behaviors, including those associated with grief, making music, art, altruism, allomothering, play, use of tools, compassion, and self-awareness (BBC 2006) evidence a highly intelligent species on par with cetaceans (DC 1999) and primates (Hart et al. 2001). The largest areas in the elephant brain are those responsible for hearing, smell, and movement coordination. The temporal lobe, responsible for processing of audio information, hearing, and language, is relatively far greater than that of dolphins (which use elaborate echolocation) and humans (who use language and symbols).
Elephants have well innervated trunks, and an exceptional sense of hearing and smell. The hearing receptors reside not only in ears, but also in trunks that are sensitive to vibrations, and most significantly feet, which have special receptors for low frequency sound and are exceptionally well innervated. Elephants communicate by sound over large distances of several kilometers partly through the ground, which is important for their social lives. Elephants are observed listening by putting trunks on the ground and carefully positioning their feet.
Their eyesight is relatively poor.
Mirror self recognition is a test of self awareness and cognition used in animal studies. Such tests were performed with elephants. A mirror was provided and visible marks were made on elephants. The elephants investigated these marks, which were visible only via the mirror. The tests also included non-visible marks to rule out the possibility of their using other senses to detect these marks. This shows that elephants recognize the fact that the image in the mirror is their own self and such abilities are considered the basis for empathy, altruism, and higher social interactions. This ability has been demonstrated in humans, apes, dolphins (Plotnik et al. 2006), and magpies (Hirschler 2008).
In addition to their bellows, roars, and widely recognized trumpet-like calls, elephants communicate over long distances by producing and receiving low-frequency sound (infrasound), a sub-sonic rumbling, which can travel through the ground farther than sound travels through the air. This can be felt by the sensitive skin of an elephant's feet and trunk, which pick up the resonant vibrations much as the flat skin on the head of a drum. This ability is thought also to aid their navigation by use of external sources of infrasound.
To listen attentively, every member of the herd will lift one foreleg from the ground, and face the source of the sound, or often lay its trunk on the ground. The lifting presumably increases the ground contact and sensitivity of the remaining legs.
Discovery of this new aspect of elephant social communication and perception came with breakthroughs in audio technology, which can pick up frequencies outside the range of the human ear. Pioneering research in elephant infrasound communication was done by Katy Payne as detailed in her book, Silent Thunder (Payne 1998). Though this research is still in its infancy, it is helping to solve many mysteries, such as how elephants can find distant potential mates, and how social groups are able to coordinate their movements over extensive range.
Reproduction and life cycle
Elephant social life revolves around breeding and raising of the calves. A female will usually be ready to breed around the age of thirteen, when for the first time she comes into estrus, a short phase of receptiveness lasting a couple of days. Females announce their estrus with smell signals and special calls.Female African elephant with calf, in Kenya.
Females prefer bigger, stronger, and, most importantly, older males. Such a reproductive strategy tends to increase their offspring's chances of survival.
After a twenty-two-month pregnancy, the mother will give birth to a calf that will weigh about 113 kilograms (250 pounds) and stand over 76 centimeters (2.5 feet) tall.
Elephants have a very long childhood. They are born with fewer survival instincts than many other animals. Instead, they must rely on their elders to teach them the things they need to know. Today, however, the pressures humans have put on the wild elephant populations, from poaching to habitat destruction, mean that the elderly often die at a younger age, leaving fewer teachers for the young.
A new calf is usually the center of attention for all herd members. All the adults and most of the other young will gather around the newborn, touching and caressing it with their trunks. The baby is born nearly blind and at first relies, almost completely, on its trunk to discover the world around it.
As everyone in the herd is usually related, all members of the tightly knit female group participate in the care and protection of the young. After the initial excitement, the mother will usually select several full-time baby-sitters, or "allomothers," from her group. According to Moss (1988), these allomothers will help in all aspects of raising the calf. They walk with the young as the herd travels, helping the calves along if they fall or get stuck in the mud. The more allomothers a baby has, the more free time its mother has to feed herself. Providing a calf with nutritious milk means the mother has to eat more nutritious food herself. So, the more allomothers, the better the calf's chances of survival. An elephant is considered an allomother during the time she is not able to have her own baby. A benefit of being an allomother is that she can gain experience or receive assistance when caring for her own calf.
Diet and ecology
Elephants are herbivores, spending 16 hours a day collecting plant food. Their diet is at least fifty percent grasses, supplemented with leaves, bamboo, twigs, bark, roots, and small amounts of fruits, seeds, and flowers. Because elephants only digest about forty percent of what they eat, they have to make up for their digestive system's lack of efficiency in volume. An adult elephant can consume 140 to 270 kilograms (300-600 pounds) of food a day.
Effect on the environment
Elephants are a species upon which many other organisms depend. One particular example of that are termites mounds: Termites eat elephant feces and often begin building their mounds under piles of elephant feces.
Elephants' foraging activities can sometimes greatly affect the areas in which they live. By pulling down trees to eat leaves, breaking branches, and pulling out roots they create clearings in which new young trees and other vegetation can establish itself. During the dry season, elephants use their tusks to dig into dry river beds to reach underground sources of water. These newly dug water holes may then become the only source of water in the area. Elephants make pathways through their environment, which are also used by other animals to access areas normally out of reach. This pathways have sometimes been used by several generations of elephants and today are converted by humans to paved roads.
Species and subspecies
African ElephantElephant crossing a river, Kenya.African bush (savanna) elephant in Mikumi National Park, Tanzania.A young elephant in Zimbabwe.
African elephants have traditionally been classified as a single species comprising two distinct subspecies, namely the savanna elephant (Loxodonta africana africana) and the forest elephant (Loxodonta africana cyclotis), but recent DNA analysis suggests that these may actually constitute distinct species (Roca 2001). This split is not universally accepted by experts (AESG 2002) and a third species of African elephant has also been proposed (Eggert et al. 2002).
This reclassification has important implications for conservation, because it means that where previously it was assumed that a single and endangered species comprised two small populations, if in reality these are two separate species, then as