Manatees are a type of very large, long lived, and intelligent marine mammals that live primarily in the coastal waters of the Gulf of Mexico, the Caribbean Sea, the Amazon Basin, and West Africa. The 3 species are: T. manatus (Gulf of Mexico and Caribbean Sea), T. inunguis (Amazon Basin), and T. senegalensis (West Africa).

While often solitary, they are also known to congregate in large numbers in shallow waters at certain times of the year. They often perform regular migrations from coastal estuary waters deep into inland river systems. This is especially true of the subspecies that inhabits the waters off of Florida (T. manatus latirostris). This subspecies makes regular migrations into the Crystal, the Homosassa, and the Chassahowitzka river systems, amongst others.

Amongst the notable qualities of the manatee, are a number that are nearly unique amongst mammals — including the fact that manatees have only 6 cervical vertebrae (possibly due to mutations in the homeotic genes). The only other mammals to only have 6 cervical vertebrae are two-toed and three-toed sloths.

Manatees are also one of the only mammals to exhibit polyphyodonty — a process whereby teeth are continuously replaced throughout life, with new teeth growing at the rear and falling out at the front, like a conveyer belt. The only other mammals to exhibit polyphyodonty are elephants and kangaroo. (Manatee have no canine or incisor teeth.)

And, perhaps most strangely, manatees are the only animal of any kind that’s known to have vascularized cornea.
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