Asian Elephants

Asian elephant skin is gray in color. Some parts of their skin sometimes lack color, especially on and around the ears, forehead and trunk. This de-pigmentation is believed to be controlled by genetics, nutrition and habitat, and generally develops as the elephant ages. Brownish to reddish hair covers the bodies of young elephants. The amount of hair reduces with age, and the color darkens.
Elephant skin varies from paper thin in some places, such as on the inside of the ears, to as thick as 1 inch (2.54 centimeters) in other places, such as around the back. Despite its thickness, the skin is sensitive, having a rich nerve supply. Elephants protect their skin from the sun and bugs by regularly covering themselves with dirt, sand and mud.
Elephants have large ears that function as cooling devices. There are many blood vessels on the inside. As elephants flap their ears on hot days, the blood in these veins cools, which then cools their brain and travels back through the body, reducing body temperature by several degrees.
Unlike other mammals, where the legs are in an angular position, the elephant's legs are stacked in an almost vertical position under the body. This positioning, along with the detailed anatomy of their long bones, provides a strong support for the animal's great weight. The vertical position of the limbs allows the elephant to remain standing for long periods without expending much energy. It also allows elephants to sleep while standing as well as while lying down.
In most mammals, the bones contain a narrow cavity. In elephants, this cavity is lacking. Instead, network of dense perforated bone occupies the space, which makes the bones stronger and able to withstand more pressure.
The elephant's skeleton is designed for mobility as well as strength. An elephant must have physical structures and coordinated muscular and neurological systems to accomplish survival skills like standing on their rear legs and climbing up and down steep slopes.
Elephants actually walk on their toes and have a thick fibrous pad on the bottom of each foot that acts as a shock absorber, protecting their leg and toe bones from jarring under their great weight and cushioning each step.
The trunk is a fusion of the nose and upper lip. It contains no bones, but is composed of muscles, blood and lymph vessels, nerves, little fat, connective tissues, skin, hair and bristles. Cartilage is found only at the base of the trunk, dividing the nostrils. The trunk has about 150,000 muscle units and tendons that provide the elephant precision as well as strength of movement.
The great dexterity of the trunk, which can perform movements of delicate precision, is due to thousands of often-tiny muscle units. These tend to be arranged either radially or longitudinally and by acting against one another, allow the trunk to be moved in any direction. Although so delicate in its movements, the trunk is also a very powerful organ that can lift heavy objects with ease.
Asian elephants have one small projection at the end of their trunk called a "finger," which aids with precision. Elephants use their trunks to take up water and squirt it into their mouths. The trunk is capable of performing many other functions as well, including: feeding, snorkeling, dusting, smelling, sifting, sorting, touching, sound production/communication, lifting, pushing, defense and offense. It can hold about 2 gallons (7.57 liters) of water. With their trunks, elephants "know" their world: their senses of smell and touch being very important.
All six sets of teeth are present in the skull at birth. They are, however, very small. Each successive set of teeth is larger, more complex, and lasts longer than the previous set. As a result, an elephant's skull grows throughout its lifetime to accommodate the new and ever-larger teeth. An elephant's age can be estimated by examining molar sequence and wear.
Tusks are modified upper incisors that grow throughout an individual's life at the rate of 2 to 3 inches (5.1 to 7.6 centimeters) a year. They are composed of ivory. Ivory is similar to bone, being made up mostly of calcium and phosphate. The tusk contains a pulp cavity, containing nerve tissues. In an adult animal, about two thirds of the tusk is visible while the remaining one third is embedded in the socket, or sulcus, in the cranium.