The average body length of an adult West Indian manatee is approximately 3 meters but some individuals can reach a length of 4.5 meters including the tail. The average weight of these manatees ranges between 200 and 600 kg, however the largest individuals can weigh up to 1,500 kg. These upper figures are unusual in manatees and females generally reach greater lengths and weights than the males of the species. Newborns measure between 1.2 and 1.4 meters and weigh approximately 30 kg. The adults are grey or brown whereas newborns are darker, a coloration they lose at about one month.
Manatees are somewhat seal-shaped with forelimbs (flippers) adapted for a completely aquatic life and no hind limbs. Lungs extend the length of the animal's body, which is important in controlling position in the water column. Hair is distributed sparsely over the body and the surface layer of skin is continually sloughing off. This is believed to reduce the build-up of algae on their skin.
(FPL 1989, Rathbun 1990)
Range mass: 200 to 1500 kg.
Average mass: 400 kg.
Range length: 4.5 (high) m.
Average length: 3 m.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: female larger
Average basal metabolic rate: 70.0056 W.