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.
- Manatees have small, flexible pectoral flippers that are used for steering, touching, scratching, and even embracing.
- 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).
- A manatee's only teeth are 24 to 32 molars located in the back of the mouth. The front molars in each row are continually being worn down by the abrasive plants the manatee eats. As the teeth wear down, new molars grow in the back of the mouth and gradually move forward. The replacement process continually provides new chewing surfaces as the teeth wear down, and continues throughout the manatee's lifetime. This unusual dental adaptation is found only in the modern manatees, suggesting that the manatee diet at an earlier time was extremely abrasive.
- In addition to molars, manatees have horny, ridged pads at the front of the upper and lower jaws which aid in crushing plant materials.
- 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