The dugong is the only living species in the family Dugongidae.
Dugongs belong to the order Sirenia, the small group of aquatic herbivorous mammals that also includes manatees. Unlike manatees, which belong to the family Trichechidae, the dugong is the sole surviving member of Dugongidae. Its scientific name is Dugong dugon.
Dugongidae was once more diverse. Its extinct relatives included Steller’s sea cow, Hydrodamalis gigas, which was hunted to extinction in the 18th century. Fossil dugongids show that the family formerly contained numerous genera and species, making the modern dugong a surviving remnant of a much larger lineage.
Dugongs live mainly in shallow coastal waters of the Indo-West Pacific, where they graze on seagrass. They are sometimes confused with manatees, but dugongs have a distinctly forked tail, while manatees have rounded, paddle-like tails. The name “sea cow” can refer to either animal, so the family distinction is the key detail.