Size
African elephants are the largest of all land animals, adult males weighing between 1,800 and 6,300 kg (2 and 7 tons/ 4,000 and 14,000 lb.). Females are smaller, weighing between 2,700 and 3,600 kg (3 and 4 tons/ 6,000 and 8,000 lb.). Shoulder height ranges between three and four m (9.8 and 13.1 ft.).
Adult male Asian elephants weigh between 1,800 and 4,500 kg (2 and 5 tons/ 4,000 and 10,000 lb.), with females weighing slightly less. Shoulder height ranges between 2 and 3.5 m (6.6 and 11.5 ft.).
Trunk
The elephant's trunk is an extension of the upper lip and nose. It functions for grasping, breathing, feeding, dusting, smelling, drinking, lifting, sound production/communication, defense/protection, and sensing.
The trunk contains an estimated 100,000 muscles and tendons in the trunk, giving it extreme flexibility and strength. Elephant trunks are capable of expanding, contracting, and moving in a diverse array of directions.
Asian elephants have one finger-like projection at the tip of the trunk and African elephants have two. These finger-like projections have many sensitive nerve endings and are capable of fine motor skills, such as grasping small and delicate objects.
An adult Asian elephant can hold up to 8.5 L (2.2 gal.) of water in its trunk. Water is sprayed into the mouth for drinking and onto the back to keep cool.
Elephants' trunks and keen sense of smell are used to survey the environment. The trunk is raised and waived in the air to gather scent particles. Through the trunk, the scent particles are then carried to a specialized gland called the Jacobson's organ, located in the roof of the mouth. The Jacobson's organ is able to gather information about the elephant's surroundings by detecting and analyzing molecules and particles from the air. Through this process, elephants are capable of locating water sources up to 19.2 km (12 mi.) away and can even determine the reproductive status of distant elephants.
Elephants can reach vegetation as high as 5.7 m (19 ft.) by rearing up onto their hind legs and extending their trunk.
Small sensory hairs extend the length of the elephant's trunk enhance its sensitivity. These small hairs facilitate tactile communication during courtship and when caring for young.
Elephant trunks are very powerful-capable of uprooting an entire tree trunk, tearing down heavy branches, and delivering a forceful blow in self-defense.
Ears
Elephant ears are about one-sixth the size of its entire body and primarily function as a cooling mechanism. The ears contain extensive networks of tiny blood vessels, which are visible at the outer margins, where the skin is only about one to two mm (0.04 - 0.08 in.) thick. The warm blood cools as it circulates through the vessels in the ear, due to the thin layer of skin that separates it from the outside air. The cooler blood then circulates back into the body, helping reduce the overall body temperature of the elephant.
The size of elephant ears is proportionate to its geographic distribution. The closer to the equator the elephant resides, the larger the ears, allowing more heat to dissipate (remove) from the body, and therefore has larger ears. African elephants live closest to the equator and have the largest ears, followed by the Asian elephants. The now extinct woolly mammoth, lived near the North Pole, and had the smallest ears.
Elephants use their ears to funnel in sound waves from the environment, contributing to their keen sense of hearing.
Dentition
Both African and Asian elephants have a total of 26 teeth including two upper incisors (tusks), 12 premolars (non-permanent teeth similar to baby teeth), and 12 molars. Asian elephants have smaller tusks than those of African elephants and females have smaller tusks than males.
Each adult male tusk weighs between 50 and 79 kg (110 - 175 lb.) and an adult female's tusk weighs between 18 and 20 kg (40 - 44 lb.). One of the heaviest tusks ever weighed was more than 100 kg (220 lb.).
African elephants have diamond-shaped ridges on their molars, whereas Asian elephants have long cylindrical ridges on theirs. The ridges help elephants grind course vegetation.
Most mammals replace cheek teeth (premolars and molars) in a vertical manner. The new tooth develops and replaces the old one, from above in the upper jaw and from below in the lower jaw. In elephants, the replacement of the cheek teeth is a horizontal process. New teeth develop at the back of the mouth and progress forward until worn out at the front.
Each molar tooth is about the size of a brick and weighs between 1.8 and 2.0 kg (4-4.5 lb.). Elephant molar teeth are replaced six times during its lifetime.
Elephants are born with temporary incisors (tusks) that are replaced with permanent ones between six and 13 months of age. Permanent tusks grow continuously at a rate of about 17 cm (6.7 in.) per year, reaching lengths of up to 3.5 m (7.7 ft.) for adult African male elephants.
The upper one-third of an elephant's tusk, where it is embedded in the bone of the upper jaw, is mostly hollow and carries a single nerve. The top third embedded portion of the tusk functions as an anchor when digging and uprooting vegetation and aids defense.
Elephant ivory is distinguished from other animal dentition by its unique cross section patterning. An elephant tusk cross section shows diamond-shaped striations, called "engine turning" and is unique to elephants.
Similar to humans, elephants may be "left or right-handed," meaning there is a preference to use one tusk over the other. As a result, one tusk may be more worn than the other.
Musth Gland/Temporal Gland
Asian and African elephants have a musth gland located just beneath the skin's surface, halfway between the eye and ear on each side of their head.
The musth gland may be associated with sexual activity and/or communication.
Annually, musth glands secrete a dark, oily, musky substance and become inflamed. This physiological change is associated with a behavior observed in male elephants called musth.
Refer to musth in the Behavior section.
Foot
The skeleton of an elephant's foot is angled, with a large pad of fat and connective tissue at the heel. The angled foot structure means that elephants walk on their tiptoes with their body weight evenly distributed across the fatty/connective tissue at the heel. Ex: An adult male Asian elephant that is 2.88 m (9.5 ft.) in height and weighs about 4,167 kg (9,259 lb.) distributes just 3.8 kg (8.5 lb.) of weight per square inch on its heels.
The elephant's unique foot structure enables secure movement over uneven terrain and swampy ground.
Skin
Elephant skin is wrinkled in appearance, with African elephants more wrinkled than Asian elephants. Wrinkles act as a cooling mechanism by increasing the skin's surface area. The additional skin and wrinkles trap moisture, which then takes longer to evaporate. Therefore, wrinkles keep elephants cooler, for longer, than if they had smooth skin.
Asian elephants are less wrinkled in appearance than African elephants because they primarily inhabit forested habitats. Temperatures are not as hot in forested areas, thereby reducing the need for forest-dwelling elephants to cool themselves.
Elephant skin can be up to 3.8 cm (1.5 in.) thick in certain places. However, the skin is sensitive to touch, detecting insects and changes in its environment.
The combination of thick skin and a thin layer of fat beneath the skin enable the elephant to tolerate cold temperatures.
Overall skin coloration for elephants is grey. However, Asian elephants have a freckled appearance due to distinct patches of depigmentation, especially on the trunk.
Hair
Elephants have sparse hair distributed unevenly on their body, with the most noticeable concentrations around the eyes, ear openings, chin, and tail.
Young elephants are hairier than adults and their hair is reddish-brown in color. As they mature, the amount of hair is reduced and becomes darker.
Internal Organs
Brain
Elephants have the largest brain of any land mammal, weighing between 4.5 to 5.5 kg (10-12 lb.).
Elephants have highly developed cerebrums and cerebellums- portions of the brain involved in movement and muscle coordination.
Elephants have large temporal lobes-portions of the brain which facilitate memory.
Elephants have excellent long-term memory and are capable of remembering experiences for long periods of time. Research has shown that elephants are able to recognize other herd members decades after they have last interacted with them.
Heart
The average weight for an elephant heart is about 12 to 21 kg (26.5-46.3 lb.) and comprises about 0.5% of the animal's total body weight.
Elephants have an atypical shaped heart. Most mammals, including humans, have a single-pointed apex at the base (heart-shaped). Elephants have a double-pointed apex at the base, lessening the heart-shaped appearance, and giving it a more circular shape.
Stomach and Intestines
Elephants have a cylindrical-shaped stomach. The stomach primarily functions in food storage. Digestion takes place in the cecum (pouch connected to the large intestine). The combined length of the small and large intestines is about 35 m (100 ft.) in length.
Lungs
Most mammals breathe air by expanding their chest, through muscular action. When the chest is expanded, a membrane (visceral pleura) attached to the lungs remains still while another membrane (parietal pleura) attached to the chest wall expands outward. The fluid-filled space between the two membranes is called the pleural cavity which widens during chest expansion. The widened pleural cavity helps create a vacuum-like effect, allowing air to be pulled into the lungs.
This process differs in elephants because they do not have a pleural cavity. Their lungs are directly attached to the chest wall and therefore rely on direct muscular action to expand the lungs. This direct muscular control enables underwater breathing with the trunk used as a snorkel.
