Wednesday, September 24, 2008

ELEPHANTS

Elephants are the largest land animals. There are three living species the African Bush Elephants the African Forest Elephant and the Asian Elephant Other species have become extinct since the last ice age, the Mammoths being the best-known of these. They were once classified along with other thick skinned animals in a now invalid order Pachydermatous.

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 lb). An elephant may live as long as 70 years, sometimes longer. The largest elephant ever recorded was shot in Angola in 1956. This male weighed about 12,000 kilograms (26,000 lb), with a shoulder height of 4.2 metres (14 ft), a metre (yard) taller than the average male African elephant. The smallest elephants, about the size of a calf or a large pig, were a prehistoric species that lived on the island of Create during the Pleistocene epoch.

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 and hominids Aristotle once said the elephant was "the beast which passeth all others in wit and mind" The word "elephant" has its origins in the Greek λέφας, meaning "ivory" or "elephant".

Healthy adult elephants have no natural predators although lions may take calves or weak individuals.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.The elephant is now a protected species worldwide, with restrictions in place on capture, domestic use, and trade in products such as ivory.

African Elephant

The Elephants of the genus Loxodonta, , known collectively as African elephants, are currently found in 37 countries in Africa.

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.

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. This split is not universally accepted by experts and a third species of African elephant has also been proposed.

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 a consequence, both could be more gravely endangered than a more numerous and wide-ranging single species might have been. There is also a potential danger in that, if the forest elephant is not explicitly listed as an endangered species, poachers and smugglers might be able to evade the law forbidding trade in endangered animals and their body parts.

The Forest elephant and the Savanna elephant can also hybridise – that is, breed together – successfully, though their preferences for different terrains reduce such opportunities. As the African elephant has only recently been recognized to comprise two separate species, groups of captive elephants have not been comprehensively classified and some could well be hybrids.

Under the new two species classification, Loxodonta africana refers specifically to the Savanna Elephant, the largest of all elephants. In fact, it is the largest land animal in the world, with the males standing 3.2 metres (10 ft) to 4 metres (13 ft) at the shoulder and weighing 3,500 kilograms (7,700 lb) to a reported 12,000 kilograms (26,000 lb).[ The female is smaller, standing about 3 metres (9.8 ft) at the shoulder Most often, Savanna Elephants are found in open grasslands marshes, and lakeshores. They range over much of the savanna zone south of the Sahara.

Physical characteristics

Trunk

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, 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.

The trunk is also used for drinking. Elephants suck water up into the trunk (up to fifteen quarts or fourteen litres 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.

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 swivelling it from side to side, like a periscope, it can determine the location of friends, enemies, and food sources.

Tusks

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.

Teeth

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.
  • 12 molars, 3 in each side of each jaw.

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 odour from the musth gland located behind their eyes. Joyce Poole, a well-known elephant researcher, has theorized that the males will fan their ears in an effort to help propel this "elephant cologne" great distances.

Intelligence

Human, dolphin and elephant brains up to scale. (1)-cerbrum (1a)-temporallobe and (2)-cerbellum

With a mass just over 5 kg (11 lb), elephant brains are larger than those of any other land animal, and although the larg

est whales have body masses twentyfold those

of a typical elephant, whale brains are barely twice the mass of an elephant's. A wide variety of behaviours, including those associated with grief, making music, art, altruism, allomthering, play, use of tools, compassion and self-awareness evidence a highly intelligent species on par with cetaceans and primates.

The largest areas in elephant brain are those responsible for hearing, smell and movement coordination, and a large portion

of the brain has to do with trunk management and sensitivity.

Senses

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, and the eyes are aiming down the trunk. An elephant has to raise his head conspicuously

to look out horizontally.

Self-awareness

Mirror self recognition

is a test of self awareness and cognition used in animal studies. A mirror was provided and visible marks were made on the elephant. The elephants investigated these marks, that 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, and magpies.

Communic

ation

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. 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 presu

mably increases the ground contact and sensitivity of the remaining legs. This ability is thought also to aid their navigation by use of external sources of infrasound. 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, of the Elephant Listening Project, and is detailed in her book Silent Thunder. 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.

Diet

Elephants are herbivores, spending 16 hours a day collecting plant food. Their diet is at least 50% grasses, supplemented with leaves, bamboo, twigs, bark, roots, and small amounts of fruits, seeds and flowers. Because elephants only digest 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 140–270 kg (300–600 lb) of food a day. 60% of that food leaves the elephant's body undigested.

Hunting

The threat to the African elephant presented by the ivory trade is unique to the species. Larger, long-lived, slow-breeding animals, like the elephant, are more susceptible to overhunting than other animals. They cannot hide, and it takes many years for an elephant to grow and reproduce. An elephant needs an average of 140 kg (300 lb) of vegetation a day to survive. As large predators are hunted, the local small grazer populations (the elephant's food competitors) find themselves on the rise. The increased number of herbivores rav

age the local trees, shrubs, and grasses. Elephants themselves have few natural predators besides man and, occasionally, lions.

Habitat loss

Another threa

t to elephant's survival in general is the ongoing cultivation of their habitats with increasing risk of conflicts of interest with human cohabitants. These conflicts kill 150 elephants and up to 100 people per year in Sri Lanka. Lacking the massive tusks of its African cousins, the Asian elephant's demise can be attributed mostly to loss of its habitat.

As larger patches of forest disappear, the ecosystem is affected in profound ways. The trees are responsible for anchoring soil and absorbing water runoff. Floods and massive erosion are common results of deforestation. Elephants need massive tracts of land because, much like the slash-and-burn farmers, they

are used to cras

hing through the forest, tearing down trees and shrubs for food and then cycling back later on, when the area has regrown. As forests are reduced to small pockets, elephants become part of the problem, quickly destroying all the vegetation in an area, eliminating all their resources.

clear that these parks may be the elephant's last hope against the rapidly changing world around them.

Humanity and elephants

Harvest from t

he wild

The harvest of elephants, both legal and illegal, 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 her

editary trait.

It is possible, if unlikely, that continued selection pressure 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 en

vironment, 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. Without tusks, elephant behaviour could change dramatically.

Elephant rage

Despite its popularity in zoos, and cuddly portrayal as gentle giants in fiction, elephants are among the world's most potentially dangerous animals. They can crush and kill any other land animal, even the rhinoceros. They can experience unexpected bouts of rage, and can be vindictive. In Africa, groups of young teenage elephants attack human villages in what is thought to be revenge for the destruction of their society by massive cullings done

in the 1970s and 80s. In India, male elephants attack villages at night, destroying homes and killing people on a regular basis. In the Indian state of jharkhand, 300 people were killed by elephants between 2000 and 2004, and in Assam, 239 people have been killed by elephants since 2001. In India elephants kills up to 200 humans every

year, and in Sri Lanka around 50 per year.

Asian elephant

(Elephas maximus)

Species, also called Asiatic elephant, belonging to the family of elephants, named by Carl Linnaeus, 1758.

Caracteristics of the asian elephant



  • T he neck is low, and then curving up
  • T he sk in is less wrenkled
  • Ears are small, looks like indian continent
  • Head has two bumps
  • Forehead is protruding
  • The underlip is long, narrow and pointed
  • Only abt 50% of bulls wear long tusks
  • Females wear trushes or nothing
  • 19 pairs of ribs (Sumatran subspecies 20)
  • The frontfeet has five nails, the hindfeet four
    (like the African forest elephant)
  • The trunktip has one prehensile protrusion



Taxonomy and distrubition

Asian elephant is a species belonging to the family of elephants (Elephantidae), which is included in the mammai order Proboscides. It was formerly called Indian elephant, which is a confusing name, since Asian elephants occur in 13 asian countries, from west India , to southern China, and in southeast from the malay peninsula to the islands Sumatra and Borneo, why "Indian" is unappropiate, and the name "Indian elephant" should be used only for the Indian subspecies.

So when speaking about the species (Elephas maximus), this species should be refered to as Asian elephant.

Population

Asian elephant was once distributed from Tigris and Euphrates Valleys of Syria and Iraq to the yellow river of China and South to Sumatra (Daniel, 1995).

Since the Asian elephant live in dense forest and djungles, is it much more difficult to estimate the present individual population number, but it is likely about 40 000 Asian elephants on earth. Of those, some 15-20 000 are kept in captivity. Europe has some 700 Asian elephants, and about the same amount is to be found in north american continent, the rest (apr. 13 500) are tame elephants in Asia.

Link: US: House Votes to Protect Elephants (H.R. 700 Asian Elephant Conservation Reauthorization Act (Concur in Senate Amendment))

Recognized subspecies:

  • Sumatran elephant (Elephas maximus sumatrensis)
  • Borneo elephant (Elephas maximus borneensis)
  • Indian elephant (Elephas maximus indicus)
  • Sri Lankan elephant (Elephas maximus maximus)

Recommended literature:
The Asian Elephant: An Action Plan for Its Conservation by Charles Santiapillai, Peter Jackson, Iucn, Ssc Asian Elephant Specialist Group.

Description

The Asian elephant is smaller than its African relatives; the easiest way to distinguish the two is that the Asian elephant has smaller ears. The Asian Elephant tends to grow to around two to four meters (7–12 feet) in height and 3,000–5,000 kilograms (6,500–11,000 pounds) in weight.

The Asian Elephant has other differences from its African relatives, including a more arched back than the African, one semi-prehensile "finger" at the tip of its trunk as opposed to two, four nails on each hind foot instead of three, and 19 pairs of ribs instead of 21. Also, unlike the African elephant, the female Asian Elephant usually lacks tusks if tusks — in that case called "tushes" — are present, they are barely visible, and only seen when the female opens her mouth. The enamel plates of the molars are greater in number and closer together in Asian elephants. Some males may also lack tusks; these individuals are called "makhnas", and are especially common among the Sri Lankan elephant population. Furthermore, the forehead has two hemispherical bulges, unlike the flat front of the African elephant. Unlike African elephants which rarely use their forefeet for anything other than digging or scraping soil, Asian elephants are more agile at using their feet in conjunction with the trunk for manipulating objects.[4]

Danger

At most seasons of the year the Indian elephant is a timid animal, much more ready to flee from a foe than to make an attack. Solitary roges are, however, frequently an exception to this rule, and sometimes make unprovoked attacks on passers-by. Rogue elephant sometimes take up a position near a road, and make it impassable to travellers. Females with calves are at all times dangerous to approach. Contrary to what is stated to be the case with the African species, when an Indian elephant makes a charge, it does so with its trunk tightly curled up, and it makes its attack by trampling its victim with its feet or knees, or, if a male, by pinning it to the ground with its tusks. During musth the male elephant is highly dangerous, not only to human beings, but to its fellow animals. At the first indications of this, domestic elephants are secured tightly to prevent any mishaps; xylazine is also used.

While elephant charges are often displays of aggression that do not go beyond threats, some elephants, such as rogues, may actually attack.

In regard to movement on land, Mr. Sanderson says that "the only pace of the elephant is the walk, capable of being increased to a fast shuffle of about fifteen miles (24 km) an hour for very short distances. It can neither trot, canter, nor gallop. It does not move with the legs on the same side together, but nearly so. A very good runner might keep out of an elephant's way on a smooth piece of turf, but on the ground in which they are generally met with, any attempt to escape by flight, unless supplemented by concealment, would be unavailing.


"When an elephant does charge, it requires all the coolness and presence of mind of the sportsman to avoid a catastrophe- "A grander animated object," writes Mr. Sanderson, "than a wild elephant in full charge can hardly be imagined. The cocked ears and broad forehead present an immense frontage; the head is held high, with the trunk curled between the tusks, to be uncoiled in the moment of attack; the massive fore-legs come down with the force and regularity of ponderous machinery; and the whole figure is rapidly foreshortened, and appears to double in size with each advancing stride. The trunk being curled and unable to emit any sound, the attack is made in silence, after the usual premonitory shriek, which adds to its impressiveness. The usual pictorial representations of the Indian elephant charging with upraised trunk are accordingly quite incorrect."

Captivity

Elephants have been captured from the wild and tamed for use by humans. Their ability to work under instruction makes them particularly useful for carrying heavy objects. They have been used particularly for timber-carrying in jungle areas. Other than their work use, they have been used in war, in ceremonies, and for carriage. They have been used for their ability to travel over difficult terrain by hunters, for whom they served as mobile hunting platforms. The same purpose is met in safaris in modern times.

The first historical record of domestication of Asian elephants was in Harappan times. Ultimately the elephant went on to become a siege engine, a mount in war, a status symbol, a work animal, and an elevated platform for hunting during historical times in South Asia.

The elephant plays an important part in the culture of the subcontinent and beyond, featuring prominently in Jataka tales and the Panchatantra. It plays a major role in Hinduism: the god Ganesh''s head is that of an elephant, and the "blessings" of a temple elephant are highly valued. Elephants have been used in processions in Kerala where the animals are adorned with festive outfits. They were also used by almost all armies in India as war elephants, terrifying opponents unused to the massive beast.

Subspecies

Elephas maximus is the only surviving species in the Elephas genus, although several extinct fossil species of Elephas are known.

There are four living subspecies of the Asian elephant:

  • Indian Elephants (E. m. indicus)
  • Sri Lankan Elephants (E. m. maximus)
  • Sumatran Elephant (E. m. sumatrensis)
  • Borneo Elephant (E. m. borneensis)