The name sea cow refers to the fact that they graze on the seagrasses which form meadows in coastal waters. As dugongs feed, whole plants are uprooted and a telltale feeding trail is left. These feeding 'scars' in the seagrass can be seen by people walking over the seagrass areas at low tide. Dugongs feed predominantly on seagrasses and show a preference for species of the genera Halophila and Halodule which are pioneer species that are low in fibre, high in available nitrogen and very digestible. Dugongs graze sparse meadows of nutritious pioneer species such as Halophila ovalis.
Scientists believe that dugong grazing promotes prolific seagrass regeneration.
An average adult consumes an estimated 25 kilograms a day. Marine algae are also consumed when seagrass is scarce. Dugongs are more closely related to elephants than to other marine mammals such as whales and dolphins, but their closest living aquatic relatives are the manatees. Manatees are aquatic mammals that live in freshwater rivers and coastal seas of West Africa, the Caribbean and America. Dugongs swim using their whale-like fluked tail and they use their front flippers for balance and turning.