The dugong (scientific name: Dugong dugon) has a downward curved muzzle, the front end of which becomes a muzzle disk with short dense bristles. The nostrils are located on the back of the muzzle end, with live flaps. The caudal lobe is horizontally positioned with a notch in the center of its posterior margin. Pulpal fin limbs without nails. Nostrils absent; premaxilla conspicuously enlarged and sharply recurved, mandibular joint correspondingly lengthened and sharply recurved. Three premolars and three molars on each side of upper and lower jaws.

Mainly distributed in the western Pacific Ocean and the Indian Ocean, preferring good water quality and an abundance of aquatic plants in the sea, regularly surfacing for air. Because female dugongs have the habit of nursing their young on the surface of the water, they are often mistaken for "mermaids". Since four thousand years ago, human beings began to kill dugongs, eating meat for oil, bone can be carved, leather can be made, so far the number of dugongs has been extremely rare.