Also known as Mermaid, it belongs to the Dugongidae family of Sirenia order, with the Latin scientific name Dugon dugong, and English name Dugong. It is a marine animal evolved from terricolous herbivore, and is the only existing strain of the Dugongidae family.   

Its spindle-shaped body is about three meters in length and 300 to 500 kilograms in weight, with sparse and short body hair all over and no obvious neck. On the small head, the upper lip is in horse-hoof shape, the mouth end protrudes with setaceous, and the two circular-like breathing holes are arranged in parallel at the front of the vertex. Behind the eyes are ear holes without auricle outline. It has no dorsal fin but an oval fin limb, under which is a pair of breasts; the wide and large tail fin has two flatly symmetrical pieces, with posterior margin in furcation and no indention. Its back is mainly in mouse color, belly slightly pale.

Dugong belongs to marine herbivorous beast. Its distribution has a close connection with water temperature, ocean current as well as its major edible food -- seaweed. Mostly haunting in seaweed clump about 20 meters away from sea coast, it sometimes comes along with tidewater into the estuary, returns to the sea along with the ebb after taking food, and seldom travels to pelagic sea. Usually a kin group of 2 to 3 head lives and moves about together at the bottom of seaweed region with favorable condition for hiding, regularly emerging at the surface for breathing. It is often considered as "mermaids" emerging at the surface, leaving many beautiful legends for people. It breeds all the year round, with gestation period of 11 to 12 months, one baby per fetus. The young one begins to find food by itself at the age of three months. The estimated lifetime is 40 years as the longest.

It is distributed in the waters of coastal regions of Guangxi Zhuang Autonomous Region, Guangdong, Hainan and southern Taiwan provinces. But due to excessive capture and killing, its remaining quantity is very small, so urgent protections are needed.

It has been listed in Appendix I of Convention on International Trade in Endangered.