There are three accepted living species of Trichechidae, representing three of the four living species in the order Sirenia: the Amazonian manatee (Trichechus inunguis), the West Indian manatee (Trichechus manatus), and the West African manatee (Trichechus senegalensis).
The West Indian manatee ranges along the North American east coast from Florida to Brazil. The Amazonian manatee species inhabit the Amazon River and the African manatee swims along the west coast and rivers of Africa. Manatees are born underwater.
Manatees don't really have any real predators. Sharks or killer whales or alligators or crocodiles could eat them, but since they don't usually inhabit the same waters, this is pretty rare. Their biggest threat is from humans. And because of this, all manatee species are endangered and threatened.
Reep found that manatee's brain, despite lacking folds (like in humans and dolphins), functions the same way as the brain of highly intelligent mammals. "The brain looks just as complex internally as any other mammalian brain," said Reep. The manatees have learned to respond to whistles and stop at underwater targets.Nov 11, 2006
As of January 7, 2016, as a result of significant improvements in its population and habitat conditions, and reductions in direct threats, the U.S. Fish and Wildlife Service announced that the West Indian manatee is proposed to be downlisted from endangered to threatened status under the Endangered Species Act (ESA).
In comparison to other mammals' teeth, Manatee teeth are very unique. Rather than having one tooth fall out and then be replaced in the same spot with another (vertically), Manatee teeth are just continually replaced horizontally (marching molars). Tooth replacement continues throughout their life.