|
|||
ElephantThe elephants (Elephantidae) are a family in the order Proboscidea in the class Mammalia. They were once classified along with other thick skinned animals in a now invalid order, Pachydermata. There are three living species: the African Bush Elephant, the African Forest Elephant (until recently known collectively as the African Elephant), and the Asian Elephant (also known as the Indian Elephant). Other species have become extinct since the last ice age, which ended about 10,000 years ago, the Mammoth being the most well-known of these.The word "elephant" has its origins in the Greek , meaning "ivory" or "elephant". Elephants are mammals, and the largest land animals alive today. 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 (265 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 kg (26,400 lb), with a shoulder height of 4.2 m (13.8 ft), a metre (3 ft 4 in) 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 Crete during the Pleistocene epoch. Elephants are symbols of wisdom in Asian cultures, and are famed for their memory and high intelligence, and 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." Elephants are 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. Elephants generally have no natural predators, although lions may take calves and occasionally adults. In some areas, lions may regularly take to preying on elephants. Asian ElephantThe Asian elephant is smaller than the African. It has smaller ears, and typically, only the males have large external tusks.The world population of Asian elephants – also called Indian Elephants or Elephas maximus – 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.[23] The Asian elephants' decline has possibly been more gradual with the causes primarily being poaching and habitat destruction by human encroachment. There are several subspecies of Elephas maximus and some have been identified only using molecular markers. The first found subspecies is the Sri Lankan Elephant (Elephas maximus maximus). Found only on the island of Sri Lanka, it is the largest of the Asians. There are only an estimated 3,0 00–4,500 members of this subspecies left today in the wild, although no accurate census has been carried out in the recent past. Large males can weigh upward to 5,400 kg (12,000 lb) and stand over 3.4 m (11 ft) tall. Sri Lankan males have very large cranial bulges, and both sexes have more areas of depigmentation than are found in the other Asians. Typically, their ears, face, trunk, and belly have large concentrations of pink-speckled skin. There is an orphanage for elephants in Pinnawala Sri Lanka, which gives shelter to disabled, injured elephants. This program plays a large role in protecting the Sri Lankan Elephant from extinction. Another subspecies, the Indian Elephant (Elephas maximus indicus) makes up the bulk of the Asian elephant population. Numbering approximately 36,000, these elephants are lighter grey in colour, with depigmentation only on the ears and trunk. Large males will ordinarily weigh only about 5,000 kg (11,000 lb) but are as tall as the Sri Lankan. The mainland Asian can be found in 11 Asian countries, from India to Indonesia. They prefer forested areas and transitional zones, between forests and grasslands, where greater food variety is available. Body characteristicsTrunkThe 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,[24] 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. 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 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. 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. Skin Elephants are called pachyderms, which means thick-skinned animals. An elephant's skin is extremely tough around most parts of its body and measures about 2.5 centimetres (1 in) thick. However, the skin around the mouth and inside of the ear is paper thin. Normally, the skin of an Asian 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. Legs and feet 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. 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 a 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. DietElephants 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.,IntelligenceWith a mass just over 5 kg ((11 lb), elephant brains are larger than those of any land animal, and although the largest 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 behaviour, including those associated with grief, making music, art, altruism, allomothering, 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.
|
|||
|
© Deepthi.com, 2003-2005. All Rights Reserved.
Contact webmaster@deepthi.com for comments and suggestions.
India India Cricket India Bollywood |
|||
