Original: 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 ) .
Simplified: They are mainly herbivores , spending most of their time grazing in shallow waters at depths of 1-2 metres ( 3-7 ft ) .