The seagrass-grazing dugong is a closer cousin of elephants than whales
Dugongs look like plump dolphins with a drooping snout, yet their nearest living relatives on land are elephants, hyraxes and the aardvark. These gentle grazers are the last survivors of a once varied family, and their only close relative, Steller's sea cow, was hunted out of existence in the 18th century.
Sirenians, the group that includes dugongs and the three manatee species, are the only plant-eating mammals to have gone fully aquatic, with a fossil record stretching back about 50 million years to the Tethys Ocean. A dugong is easy to tell from a manatee by its notched, dolphin-style tail and its sharply bent snout, built for cropping seagrass from the seabed with a muscular, horseshoe-shaped upper lip.
Their bones are among the densest of any animal, solid and nearly free of marrow, and probably work as ballast to keep them hovering just below the surface. Adults seldom pass 3 metres, though a record animal found off western India measured 4.06 metres and weighed 1,016 kilograms. Males grow tusks at puberty, and counting growth layers in a tusk reveals an animal's age. Their eyes are tiny, but their hearing is sharp, and valves seal the nostrils on top of the head.
The name comes from a Philippine word first popularised by the French naturalist Buffon in 1765; despite a popular belief, it does not mean lady of the sea. Locals have also called the animal sea cow, sea pig and sea camel.
Dugongs roam warm coasts from the western Pacific to East Africa, with northern Australia considered their stronghold. People have hunted them for meat and oil for thousands of years, and traditional hunting still matters culturally in northern Australia and the Pacific Islands. Numbers have fallen about 20 percent over the last 90 years, and they have vanished from Hong Kong, Mauritius and Taiwan. Living 70 years or more but breeding slowly, they are listed as vulnerable.
Source: Dugong
