Asian elephants are the continent's largest terrestrial mammals. They can reach 6.4m in length and 3m at the shoulder, and weigh as much as 5 tonnes.
They are smaller than African elephants and have proportionally smaller ears, which they keep in constant motion in order to cool themselves. They also have a single 'finger' on the upper lip of their trunks as opposed to African elephants, which have a second one on the lower tip.
Their skin ranges from dark grey to brown, with patches of pink on the forehead, the ears, the base of the trunk and the chest.
A significant number of male Asian elephants are tuskless. The percentage of males with ivory varies from just 5% in Sri Lanka to aound 90% in southern India - possibly reflecting the intensity of past ivory hunting.
There are three subspecies of Asian elephant – the Indian, Sumatran and Sri Lankan. The Indian has the widest range and accounts for the majority of the remaining elephants on the continent. The Sri Lankan is physically the largest of the subspecies, and also the darkest in colour. The Sumatran is the smallest.
However, some studies suggest that Borneo pygmy elephants could be a separate subspecies. If so, they would be the smallest. They are also more rotund and have babyish faces, larger ears, and longer tails that almost reach the ground. They are appear to be less aggressive than other Asian elephants.
Female elephants are more social than males. They form herds of related females that are led by the oldest female, the 'matriarch'. Males usually live alone but sometimes form small groups with other males.
When habitat conditions are favourable, female elephants may give birth to a calf every 2.5-4 years. Each calf weighs between 50-150kg.
After several months, the calf begins to eat grass and foliage. However, it stays under the supervision of its mother for several years, starting to make its first independent moves when it is around 4 years old.
Both males and females may become sexually mature as early as 9, but males do not usually start sexual activity until they are 14 or 15. And even then they are not capable of the social dominance that is usually necessary for successful reproductive activity, especially as most elephants only reach their full size at about 17 years of age.
Elephants need to eat an average of 150 kg per day to survive. They can spend more than two thirds of each day feeding on grasses. But they also devour large amounts of bark, roots, leaves and stems. Cultivated crops such as bananas, rice and sugarcane are also favoured foods - sometimes bringing them into conflict with humans.
They need to drink at least once a day so they are always close to a source of fresh water.