Elephant

Elephantidae (the elephants) is a family of animals, the only family in the order Proboscidea that still exists today. Elephantidae has three living species: the Savannah Elephant and Forest Elephant (which were collectively known as the African Elephant) and the Asian Elephant (formerly known as the Indian Elephant). During the last ice age there were more species, which are now extinct.

Zoology

Body characteristics

After their size, an elephant's most obvious characteristic is the single trunk, a type of muscular hydrostat, that is a much elongated combination of nose and upper lip. The tip of an elephant's trunk contains pacinian corpuscles and finger-like projections used to manipulate small objects and to pluck grasses. The trunk is a useful and muscular appendage that enables an elephant to reach food in high places and lift obstacles weighing up to 400 kg. Elephants are able to pull up to 12 litres (2.5 Imperial or 3 U.S. gallons) of water into the trunk to be sprayed into the mouth for drinking or onto the back for bathing. A trunk is also used for breathing and can be used as a snorkel when wading in deep water.

Related Topics:
Trunk - Muscular hydrostat - Nose - Lip - Pacinian corpuscle - Appendage - Litre

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Elephants also have tusks, large teeth emerging from their upper jaws. The longest elephant tusks were recorded to be 3.5 metres long. Elephant tusks are the major source of ivory, but because of the increased rarity of elephants, hunting and ivory trade is now restricted, and in some countries illegal.

Related Topics:
Tusk - Metre - Ivory - Hunting

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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.

Related Topics:
Premolar - Molar - Malnutrition - Loxodont - Genus

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Skin diseases often occur, from which they try to protect themselves by taking mud baths, showering one another with water from the trunk, and rolling in dust. The skin can therefore appear brown or reddish, but the natural color is light gray. Their coarse and wrinkled skin is sparsely bristled, and about 1 inch (25 mm) thick. There are also rare white elephants, who often have blue eyes. Otherwise elephants have brown eyes, surrounded by long lashes.

Related Topics:
Skin disease - Skin - White elephant

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They have large ears that they can wave to cool themselves down, and a relatively small tail with a brush at its tip.

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Walking at a normal pace an elephant covers about 2 to 4 miles an hour (3 to 6 km/h) but they can reach 24 miles an hour (40 km/h) at full speed.

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Evolution

Although the fossil evidence is uncertain, some scientists believe there is genetic evidence that the elephant family shares distant ancestry with the Sirenians (sea cows) and the hyraxes. In the distant past, members of the hyrax family grew to large sizes, and it seems likely that the common ancestor of all three modern families was some kind of amphibious hyracoid. One theory suggests that these animals spent most of their time under water, using their trunks like snorkels for breathing. The modern elephants too can swim using their trunks in that manner for up to 6 hours and 50 km.

Related Topics:
Sirenia - Hyrax - Snorkel

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In the past, there was a much wider variety of elephant genera, including the mammoths, stegodons and deinotheria.

Related Topics:
Mammoth - Stegodon - Deinotheria

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Varieties

It has long been known that the African and Asian elephants are separate species. African elephants tend to be larger than the Asian species (up to 4 m high and 7500 kg) and have bigger ears (which are rich in veins and thought to help in cooling off the blood in the hotter African climate). Male and female African elephants have long tusks, while male and female Asian Elephants have shorter tusks, with the female's being almost non-existent. African elephants have a dipped back, smooth forehead and two "fingers" at the tip of their trunks, as compared with the Asian species which have an arched back, two humps on the forehead and have only one "finger" at the tip of their trunks.

Related Topics:
African - Asian

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There are two populations of African elephants, Savannah and Forest, and recent genetic studies have led to a reclassification of these as separate species, the forest population

Related Topics:
Savannah - Forest

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now being called Loxodonta cyclotis, and the Savannah (or Bush) population termed Loxodonta africana. 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.

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The Forest elephant and the Savannah elephant can hybridise successfully, though their preference for different terrains reduces the opportunities to hybridise. Many captive African elephants are probably generic African elephants as the recognition of separate species has occurred relatively recently.

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Although hybrids between different animal genera are usually impossible, in 1978, an Asian elephant cow gave birth to a hybrid calf sired by an African elephant bull (the old terms are used here as this pre-dates current classifications). The pair had mated several times, but pregnancy was believed to be impossible. "Motty", the resulting hybrid male calf, had an African elephant's cheek, ears (large with pointed lobes) and legs (longer and slimmer), but the toenail numbers, (5 front, 4 hind) and the single trunk finger of an Asian elephant. The wrinkled trunk was like an African elephant. The forehead was sloping with one dome and two smaller domes behind it. The body was African in type, but had an Asian-type centre hump and an African-type rear hump. Sadly the calf died of infection 12 days later. It is preserved as a mounted speciment at the British Natural History Museum, London. There are unconfirmed rumours of three other hybrid elephants born in zoos or circuses, all of were said to have been deformed and did not survive.

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Diet

Elephants are herbivores, spending 16 hours a day collecting plant food. 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 (140 to 270 kg) of food a day. 60% of that food leaves the elephant's body undigested.

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Social behavior

In the wild, elephants exhibit complex social behavior and strong familial bonds. Most females will live in family groups with up to 200 mothers, daughters and sisters. Males, on the other hand, are commonly found living alone or in smaller ( up to 20) temporary bachelor groups. Social hierarchy in calf-cow groups is based on size and age, with the largest and oldest at the top and the smallest and youngest coming in last. Adolescent males determine their own ranking order through jousting contests using head and tusks, where strength and temperament are as important as size and age. Generally, though, males are very tolerant of each other. The exception is when a female is in estrus. Bulls will roam from female group to group, staying with a specific female in estrus for a couple of days to ensure fertilization and will have no part in raising the calf. Females in estrus try not to court males, but usually choose a mate based on size and dominance, which tends to be a male in musth.

Related Topics:
Estrus - Musth

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They communicate with very low and long-ranging subsonic tones.

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Elephants, especially males, have been known to knock down trees when excited, socially pressured, or when looking for food.

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Reproduction

• Females (cows) reach sexual maturity at around 9-12 years of age and become pregnant for the first time, on average, around age 13. They can reproduce until ages 55-60.
• Females give birth at intervals of about every 5 years.
• Although males (bulls) reach sexual maturity around age 10, they often do not breed until they are about 30 when they become large and strong enough to compete successfully with other large bulls for the attention of females.
• An elephant's gestation period lasts about 22 months (630-660 days), the longest gestation period of any mammal, after which one calf typically is born. Twins are rare.
• The initial signs of labor include: bulging beneath the tail, general discomfort, and straining. Also, the pregnant elephant's progesterone (a hormone that maintains pregnancy) level drops approximately 3-5 days prior to the onset of labor.
• Labor ranges in length from 5 minutes to 60 hours. The average length of labor is 11 hours.
• At birth, calves weigh around 90-115 kilograms (200-250 pounds), and they gain 1 kilogram (2-2.5 pounds) a day.
• In the wild, the mother is accompanied by other adult females (aunts) that protect the young.
• In the wild, baby elephants are raised and nurtured by the whole family group, practically from the moment they are born.

Motherhood and calf rearing

• The first sound a newborn calf usually makes is a sneezing or snorting sound to clear its nasal passages of fluids. (In the first few minutes after a captive birth, the keepers must monitor the calf closely for the first sound or movement. Whichever happens first, the mother typically responds to her new baby with surprise and excitement.)
• With the help of its mother, a newborn calf usually struggles to its feet within 30 minutes of birth. For support, it will often lean on its mother's legs.
• A newborn calf usually stands within one hour and is strong enough to follow its mother in a slow-moving herd within a few days.
• Unlike most mammals, female elephants have a single pair of mammary glands located just behind the front legs. When born, a calf is about 3 feet (90 cm) high, just tall enough to reach its mother's nipples.
• A calf suckles with its mouth, not its trunk, which has no muscle tone. To clear the way to its mouth so it can suckle, the calf will flop its trunk onto its forehead.
• A newborn calf suckles for only a few minutes at a time but will suckle many times per day, consuming up to 11 litres (3 gallons) of milk in a single day.
• A calf may nurse for up to 2 years of age or older. Complete weaning depends on the disposition of the mother, the amount of available milk, and the arrival of another calf.
• Newborn calves learn primarily by observing adults, not from natural instinct. For example, a calf learns how to use its trunk by watching older elephants using their trunks.
• It takes several months for a calf to control the use of its trunk. This can be observed as the calf trips over its trunk or as the trunk wiggles like a rubbery object when the calf shakes its head.