Manatees can be found either exclusively in freshwater, or they may move between fresh and salt water, depending on the species.
Many manatees in the Caribbean region bear scars on their backs from being run over by powerboats, the wounds inflicted by the propellors. They swim quite slowly in general, at speeds of around 8 kph (5 mph), although they can accelerate to 30 kph (20 mph) over short distances. Manatees have an enlarged organ called a caecum at the junction between the large and small intestines, which helps digest the plant matter that forms the basis of their diet.
Distribution: West Indian manatees range from Florida through the Caribbean. The freshwater Amazonian manatee occurs in the Amazon region, and there is a West African species.
Habitat: Coastal waters.
Weight: 400 - 550 kg (900 - 1200 lb); females are usually larger.
Length: 2.8 - 3.6 m (9 - 11.8 ft).
Maturity: 8 - 18 years.
Gestation Period: About 12 months.
Breeding: 1; young suckle upside down beneath their mother’s body; weaning occurs at 12 - 18 months.
Diet: Herbivorous, grazing on a wide variety of vegetation; has been documented feeding on over 50 different aquatic plants.
Lifespan: Up to 65 years.
Teeth are replaced from behind as they wear down. Manatees typically only have six grinding-type teeth.
These front limbs have nails. There are no hind limbs.
A primitive trunk
The upper lip is prehensile and divided into two parts, helping the manatee to feed.
Manatees frequent shallow stretches of water, where they can graze, typically to depths of 2.5 m (7 ft).
An easy way of distinguishing manatees is by their rounded, paddle-shaped tail.
Manatees will uproot aquatic plants, holding them in their flippers to eat.
These manatee is a plant-eating aquatic mammal. It lives between the mouths of the Senegal River (the border between Mauritania and Senegal) in the north and the Cuanza River in Angola. It occupies shallow coastal water and often swims in the mouths of rivers and swamps.
This species is very similar to the West Indian manatee, which lives in the Caribbean and Florida. It has large, flexible lips and thick bristles. Their tails are more rounded than those of the dugongs.
Manatees are plant eaters and consequently have long guts. Bacteria in the gut break down the tough plant food. Plant food also gradually wears down the teeth. To counter this, the manatees use the same system as their relatives, the elephants. As worn teeth become useless, they are pushed out at the front. New teeth are exposed at the back of the mouth, and gradually move to the front, pushed along by more teeth behind. The supply of teeth is not endless, but it is enough to last for a normal lifetime.
Distribution: Western Africa.
Habitat: Coastal waters and freshwater river mouths.
Food: Water plants.
Size: 3.7-4.6m (12 - 15 ft); 1.6 tonnes (3,500 lb).
Maturity: 3 years.
Breeding: Calves born in late spring and summer.
Life span: 28 years.
West Indian Manatee
Despite their appearance, manatees are not cetaceans. Neither are they related to seals (pinnipeds). These marine mammals belong to the Sirenia order, as do the dugongs - similar animals from South-east Asia. Sirenians evolved to live in water separately from whales and seals. In fact, they are believed to be more closely related to elephants than other sea mammals. Like elephants, they are vegetarian, not carnivorous.
Manatees live in both salt and fresh water, although they spend more time in fresh-water habitats. They rarely stray far from land, and may travel considerable distances up rivers to sources of warm water.
Manatees have wrinkled grey-brown skin with a sparse covering of fine hairs. Their fore-flippers have nails on their upper surfaces, while their upper lips, which are very manoeuvrable, have moustaches of thick bristles.
Manatees feed both during the day and at night. They use their dextrous lips to pluck leaves from water hyacinths, sea grasses and other aquatic plants. Although they do not actively seek them out, the manatees also eat the invertebrates, such as water snails and insect larvae, that live on these plants. The single young is born after about a year’s gestation.
Distribution: Coast of Florida to Brazil.
Habitat: Estuaries and shallow coastal water.
Food: Water plants and aquatic invertebrates.
Size: 2.5 - 4.5 m (8.25 - 14.75 ft); 500 kg (1,100 lb).
Maturity: 8 - 10 years.
Breeding: Single young born every 2 - 3 years.
Life span: 30 years.