|Asian Elephant range|
The Asian Elephant (Elephas Maximus) is an elephant species living in Asia. They are more easily tamed than larger African elephants. People have used them as working animals for hundreds of years. It is the national animal of India.
In general, the Asian elephant is smaller than the African bush elephant and has the highest body point on the head. The back is convex or level. The ears are small with dorsal borders folded laterally. It has up to 20 pairs of ribs and 34 caudal vertebrae. The feet have more nail-like structures than those of African elephants—five on each forefoot, and four on each hind foot.
On average, males are about 2.75 m (9.0 ft) tall at the shoulder and 4 t (4.4 short tons) in weight, while females are smaller at about 2.4 m (7.9 ft) at the shoulder and 2.7 t (3.0 short tons) in weight. Length of body and head including trunk is 5.5–6.5 m (18–21 ft) with the tail being 1.2–1.5 m (3.9–4.9 ft) long. The largest bull elephant ever recorded was shot by the Maharajah of Susang in the Garo Hills of Assam, India in 1924, it weighed 7 t (7.7 short tons), stood 3.43 m (11.3 ft) tall at the shoulder and was 8.06 m (26.4 ft) long from head to tail. There are reports of larger individuals as tall as 3.7 m (12 ft).
The distinctive trunk is an elongation of the nose and upper lip combined; the nostrils are at its tip, which has a one finger-like process. The trunk contains as many as 60,000 muscles, which consist of longitudinal and radiating sets. The longitudinals are mostly superficial and subdivided into anterior, lateral, and posterior. The deeper muscles are best seen as numerous distinct fasciculi in a cross-section of the trunk. The trunk is a multipurpose prehensile organ and highly sensitive, innervated by the maxillary division of the trigeminal nerve and by the facial nerve. The acute sense of smell uses both the trunk and Jacobson's organ. Elephants use their trunks for breathing, watering, feeding, touching, dusting, sound production and communication, washing, pinching, grasping, defense and offense.
The "proboscis" or trunk consists wholly of muscular and membranous tissue, and is a tapering muscular structure of nearly circular cross-section extending proximally from attachment at the anterior nasal orifice, and ending distally in a tip or finger. The length may vary from 1.5 to 2 m (59 to 79 in) or longer depending on the species and age. Four basic muscle masses—the radial, the longitudinal and two oblique layers—and the size and attachments points of the tendon masses allow the shortening, extension, bending, and twisting movements accounting for the ability to hold, and manipulate loads of up to 300 kg (660 lb). Muscular and tendinous ability combined with nervous control allows extraordinary strength and agility movements of the trunk, such as sucking and spraying of water or dust and directed air flow blowing.
The trunk can hold about four litres of water. Elephants will playfully wrestle with each other using their trunks, but generally use their trunks only for gesturing when fighting.
Tusks serve to dig for water, salt, and rocks, to debark and uproot trees, as levers for maneuvering fallen trees and branches, for work, for display, for marking trees, as weapon for offense and defense, as trunk-rests, and as protection for the trunk. Elephants are known to be right or left tusked.
Female Asian elephants usually lack tusks; if tusks—in that case called "tushes"—are present, they are barely visible, and only seen when the mouth is open. 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 "filsy 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. They can sometimes be known for their violent behaviour.
A record tusk described by George P. Sanderson measured 5 ft (1.5 m) along the curve, with a girth of 16 in (41 cm) at the point of emergence from the jaw, the weight being 104 1⁄2 lb (47.4 kg). This was from an elephant killed by Sir Brooke and measured 8 ft (2.4 m) in length, and nearly 17 in (43 cm) in circumference, and weighed 90 lb (41 kg). The tusk's weight was, however, exceeded by the weight of a shorter tusk of about 6 ft (1.8 m) in length which weighed 100 lb (45 kg).
Skin colour is usually grey, and may be masked by soil because of dusting and wallowing. Their wrinkled skin is movable and contains many nerve centers. It is smoother than that of African elephants, and may be depigmented on the trunk, ears, or neck. The epidermis and dermis of the body average 18 mm (0.71 in) thick; skin on the dorsum is 30 mm (1.2 in) thick providing protection against bites, bumps, and adverse weather. Its folds increase surface area for heat dissipation. They can tolerate cold better than excessive heat. Skin temperature varies from 24 to 32.9 °C (75.2 to 91.2 °F). Body temperature averages 35.9 °C (96.6 °F).
Asian elephants are highly intelligent and self-aware. They have a very large and highly convoluted neocortex, a trait also shared by humans, apes and certain dolphin species. Elephants have a greater volume of cerebral cortex available for cognitive processing than all other existing land animals, and extensive studies place elephants in the category of great apes in terms of cognitive abilities for tool use and tool making. They exhibit a wide variety of behaviours, including those associated with grief, learning, allomothering, mimicry, play, altruism, use of tools, compassion, cooperation, self-awareness, memory, and language. Elephants are reported to go to safer ground during natural disasters like tsunamis and earthquakes, although there have been no scientific records of this since it is hard to recreate or predict natural disasters.
Distribution and habitat
Asian elephants inhabit grasslands, tropical evergreen forests, semi-evergreen forests, moist deciduous forests, dry deciduous forests and dry thorn forests, in addition to cultivated and secondary forests and scrublands. Over this range of habitat types elephants occur from sea level to over 3,000 m (9,800 ft). In the eastern Himalaya in northeast India, they regularly move up above 3,000 m (9,800 ft) in summer at a few sites.
In Bangladesh, some isolated populations survive in the south-east Chittagong Hills. A herd of 20–25 wild elephants was reported as being present in the Garo Hills of Mymensingh in the late-1990s, being detached from a big herd in the Peack hills of India and prevented from returning by fences put up in the meantime by the Indian border security force. The herd was estimated at about 60 individuals in 2014.
Three subspecies are recognised:
- the Sri Lankan elephant occurs in Sri Lanka;
- the Indian elephant occurs in mainland Asia: Bangladesh, Bhutan, Cambodia, China, India, Laos, Malay Peninsula, Myanmar, Nepal, Thailand, Vietnam;
- the Sumatran elephant occurs in Sumatra.
The Borneo elephant occurs in Borneo's northern and northeastern parts. In 2003, mitochondrial DNA analysis and microsatellite data indicated that the Borneo elephant population is derived from stock that originated in the region of the Sunda Islands. The genetic divergence of Borneo elephants warrants their recognition as a separate Evolutionarily Significant Unit.
Ecology and behaviour
Elephants are crepuscular. They are classified as megaherbivores and consume up to 150 kg (330 lb) of plant matter per day. They are generalist feeders, and both grazers and browsers, and were recorded to feed on 112 different plant species, most commonly of the order Malvales, and the legume, palm, sedge and true grass families. They browse more in the dry season with bark constituting a major part of their diet in the cool part of that season. They drink at least once a day and are never far from a permanent source of fresh water. They need 80–200 litres of water a day and use even more for bathing. At times, they scrape the soil for clay or minerals.
Adult females and calves may move about together as groups, but adult males disperse from their mothers upon reaching adolescence. Bull elephants may be solitary or form temporary 'bachelor groups'.
Cow-calf unit sizes generally tend to be small, typically consisting of three adult females which are most likely related, and their offspring; however, larger groups containing as many as 15 adult females may occur. There can also be seasonal aggregations containing 100 individuals at a time, including calves and subadults. Until recently, Asian elephants, like African elephants, were thought to typically follow the leadership of older adult females, or matriarchs, but females can form extensive and very fluid social networks, with individual variation in the degree of gregariousness. Social ties generally tend to be weaker than in African elephants.
Elephants are able to distinguish low amplitude sounds. They use infrasound to communicate; this was first noted by the Indian naturalist Krishnan and later studied by Payne.
Tiger predation on Asian elephants is rare but is not restricted only to small calves.
Bulls will fight one another to get access to oestrous females. Strong fights over access to females are extremely rare. Bulls reach sexual maturity around the age of 12–15. Between the age of 10 and 20 years, bulls undergo an annual phenomenon known as "musth". This is a period where the testosterone level is up to 100 times greater than non-musth periods, and they become aggressive. Secretions containing pheromones occur during this period, from the paired temporal glands located on the head between the lateral edge of the eye and the base of the ear.
The gestation period is 18–22 months, and the female gives birth to one calf, only occasionally twins. The calf is fully developed by the 19th month, but stays in the womb to grow so that it can reach its mother to feed. At birth, the calf weighs about 100 kg (220 lb), and is suckled for up to three years. Once a female gives birth, she usually does not breed again until the first calf is weaned, resulting in a four to five year birth interval. Females stay on with the herd, but mature males are chased away.
Asiatic elephants reach adulthood at 17 years of age in both sexes. Elephants' life expectancy has been exaggerated in the past. They live on average for 60 years in the wild and 80 in captivity.
Females produce sex pheromones. A principal component thereof, (Z)-7-dodecen-1-yl acetate, has also been found to be a sex pheromone in numerous species of insects.
Interaction with humans
At most seasons of the year, Asian elephants are timid and much more ready to flee from a foe than to attack. However, solitary rogues are frequently an exception to this rule, and sometimes make unprovoked attacks on passers-by. Rogue elephants sometimes take up a position near a road, making it impassable to travelers.
Females with calves are at all times dangerous to approach. When an Asian elephant makes a charge, it tightly curls up its trunk and attacks by trampling its victim with feet or knees, or, if a male, by pinning it to the ground with its tusks. During musth, bulls are highly dangerous, not only to human beings, but also to other animals. At the first indications, trained elephants are secured tightly to prevent any mishaps.
The first historical record of the 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 beast of burden, and an elevated platform for hunting during historical times in South Asia.
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. It is reported that war elephants are still in use by the Kachin Independence Army (KIA) to defend Kachin State in northern Myanmar against domination by Myanmar's military. The KIA use about four dozen elephants to carry supplies. 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 pre-eminent threats to Asian elephants today are loss, degradation and fragmentation of habitat, leading in turn to increasing conflicts between humans and elephants. They are poached for ivory and a variety of other products including meat and leather.
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