(Science: zoology) An order of large aquatic herbivorous mammals, including the manatee, dugong, rytina, and several fossil genera.
The hind limbs are either rudimentary or wanting, and the front ones are changed to paddles. They have horny plates on the front part of the jaws, and usually flat-crowned molar teeth. The stomach is complex and the intestine long, as in other herbivorous mammals. See cetacea .