The dugong inhabits the tropical and subtropical coastal and island waters in the Indo-Pacific from East Africa to Vanuatu, between 26ºN and 26ºS latitudes. It is a member of the order Sirenia, which also includes three species of manatees and is the only member of the family Dugongidae.
Although the dugong is an herbivorous animal like the manatee, it is strictly marine. Large distances often separate dugong stocks, thought to be relict populations, although the animal is known to be able to traverse vast expanses of ocean. Human exploitation has led to extinction of the species in several archipelagoes, including Mascarene, Laccadive, the Maldives, Barren, Narcondam, Cocos (Keeling), and Christmas Islands around the rim of the Indian Ocean, and the Lesser Sunda Islands in Indonesia east of Java. This makes the dugong vulnerable to over-exploitation. The rate of change of a dugong population is most sensitive to changes in adult survivorship. Even a slight reduction in adult survivorship as a result of habitat loss, disease, hunting or incidental drowning in nets, can cause a chronic decline.