Adult West Indian and West African manatees average about 3 m (10 ft.) in length. Large individuals may reach lengths of up to 4 m (13 ft.). Average adult weights are approximately 363 to 544 kg (800-1,200 lb.). One particularly large Florida manatee weighed 1,655 kg (3,650 lb.). Females are generally larger than males.

Amazonian manatees are the smallest of all three species. They are shorter and more slender. The longest specimen measured 2.8 m (9.2 ft.). A large individual weighed 480 kg (1,058 lb.).

The manatee's body is streamlined-full around the middle and narrowing to a paddle-shaped tail.

The true color of a manatee is gray, although it may appear brownish-gray.

Amazonian manatees usually have white or pink patches on the belly and chest.

Organisms such as algae, which may grow on the skin of slow-moving individuals, alter the body color and make some manatees look more green or brown.

The two small pectoral flippers on a manatee's upper body are used for steering. These flexible flippers may also be used for bringing food to the manatee's mouth and guiding movement along a waterway's bottom. The flippers can also be used for touching, scratching, and even embracing other manatees (Nowak and Paradiso, 1983).

West Indian and West African manatees have three or four fingernail-like the toenails on an elephant's feet-at the tips of their flippers. Amazonian manatees lack fingernails.

Manatee flippers have five digits that are covered by a thick layer of skin. This bone structure is similar to that of toothed whales, seals, and sea lions.

Hind limbs are absent. Vestigial pelvic bones, which are not connected to the vertebral column, are found deep in the pelvic musculature.

Manatees have no external discernable neck.

Manatees do not have external ear flaps. The tiny opening to the ear canal is located several centimeters behind the eye.

The nostrils lie at the end of the snout on the upper surface. They close automatically when a manatee submerges.

Manatees have a large flexible upper lip. Their lips help guide vegetation into the mouth. Vibrissae (whiskers) are found on the surface of the upper lip. Each vibrissa is separately attached to nerve endings and has its own supply of blood.

Small eyes (about 2 cm or 0.8 in. in diameter) are located on the sides of the head. The iris has a color ranging from blue to brown (Griebel and Schmid, 1996).

The tail is evenly rounded and forms a paddle shape.

A manatee swims by moving its large paddle-like tail in an up-and-down motion.

A manatee has sparse hairs scattered over its body, with the largest concentration around the snout area.