The dugong, like all sea cows, is herbivorous. It primarily grazes on sea grasses and therefore spends most of its time in sea grass beds. Unlike the closely related manatees, the dugong never enters freshwater and is therefore the only exclusively marine mammal that is herbivorous. As in most herbivores, the dugong’s brain is very small compared to its body size, likely because it does not have to develop complex hunting strategies to capture prey.

Dugongs reproduce via internal fertilization and give birth to large young, which they nurse for as long as a year and a half. Adult dugongs do not have any natural predators, but juveniles may be eaten by saltwater crocodiles, killer whales, and large, coastal sharks.

The dugong has some or complete legal protection throughout most of its range, but it is still hunted in some places and is threatened by habitat destruction, collision with boats, and accidental capture in fisheries targeting other species throughout most of its range. Populations are depleted in some places and regionally extinct in others, and scientists believe the dugong to be vulnerable to extinction. Without careful management of the human activities that threaten the dugong, it could be lost from more places.

Note on a closely related species: In addition to the dugong and the manatees, another species of sea cow used to be common in the north Pacific Ocean. The Steller’s sea cow (Hydrodamalis gigas) was the only other species in the Dugongidae family in modern times, but it was hunted to extinction by hunters and explorers in the 1700s. Formerly one of the largest marine mammals after the great whales, the Steller’s sea cow will never live again. That species provides an example of what is possible if hunting or fishing happens to an unsustainable degree.