Marine Wildlife Encyclopedia
West Indian Manatee Trichechus manatus
This is the largest species of manatee, and also the best studied—something explained partly by its distribution, which extends northward as far as Florida. Unlike the West African manatee, it often ventures into coastal waters, although it avoids regions where the winter temperature drops below 68°F (20°C).
Its skin is gray, but its upper surface is often colonized by algae, which gives it a greenish tinge. Its vision and hearing, provided by small eyes and ears, are not very acute, but its mobile lips are covered with sensitive bristles, which it uses to find underwater plants in depths of up to about 13 ft (4 m). It needs to consume approximately one-quarter of its body weight in food each day. Although its diet is mainly vegetarian, it sometimes eats fish to obtain protein.
Manatees and dugongs owe their blimplike shapes partly to the large amounts of gas generated as they digest their food. To compensate for this, they have unusually dense bones, which help them to maintain neutral buoyancy. West Indian manatees usually live in groups of up to 20 animals, and when food is plentiful, groups may increase to over a hundred individuals.
In the past, West Indian manatees were hunted for their meat, skin, and oil, which was sometimes used in lamps. Today, the main threats facing them are pollution and collisions with boats. In Florida, where boat traffic is heavy, many manatees bear the scars of their encounters with boats.