Dugongs eat about 1 pound of sea grass for every 10 pounds they weigh. When eating sea grass, dugongs must clean it using their nose and flippers by shaking it wildly. Baby dugongs nurse by drinking their mother's milk while the mother swims just below the surface and sometimes grazes at the same time. Dugongs have two tiny nostrils on top of their snout to breathe while much of their body is submerged as they swim or sleep. Over a million years ago, dugongs had front and back legs but have since evolved to live exclusively in the water.