Manatees average 3 m (10 ft.) and 363 to 544 kg (800–1,200 lb.). Manatees have paddlelike tails and foreflippers, and no hind limbs.

Manatees belong to the mammalian order Sirenia. There are three species of manatee: Trichechus inunguis, the Amazonian manatee; Trichechus senegalensis, the West African manatee; and Trichechus manatus, the West Indian manatee. Scientists also recognize two subspecies of West Indian manatee: T.m. latirostris, the Florida manatee, and T.m. manatus, the Antillean manatee. The order Sirenia has one other living species, the dugong. A fifth species, Steller’s sea cow, was hunted to extinction by 1768.

All manatees inhabit tropical and subtropical waters of North and South America and Africa. The West Indian and West African manatees live in rivers, bays, estuaries, and coastal areas. They can move freely between freshwater and saltwater habitats. The Amazonian manatee is restricted to the freshwater Amazon basin.

All manatees are herbivores. The Florida manatee feeds on more that 60 varieties of grasses and plants. A manatee’s only teeth are molars, for grinding vegetation. Some research suggests that manatees periodically require fresh water. West Indian manatees have been seen congregating at river mouths and drinking from hoses, culverts, and sewage outfalls.

A female manatee, called a cow, gives birth about once every three years. Gestation lasts about 12 months. At birth, West Indian manatees measure about 1.2 to 1.4 m (4–4.5 ft.) and weigh 27 to 32 kg (60–70 lb.). A calf nurses from teats under the mother’s pectoral flippers.

Florida manatees are highly susceptible to cold; it’s not unusual for them to die during extremely cold weather. But human activities pose a much greater threat to manatees. Each year, many Florida manatees are killed and injured by watercraft, the greatest human-induced cause of Florida manatee deaths. Other threats include entanglement, poaching, and habitat destruction. All manatees are threatened or endangered. They are protected by national and local legislation in every country in which they are found.