Manatees spend six to eight hours each day feeding on more than 60 species of aquatic or semi-aquatic plants, including sea grasses, mangrove leaves, and water hyacinths. They feed only on plants and eat 8 to 11 percent of their body weight each day to replenish the energy they use to maintain body temperature. All of their teeth are molars used for chewing and grinding food, and because many of the plants they eat contain sand and shells, worn teeth fall out and are replaced by new molars that push the other teeth forward into empty spaces, a process called marching molars. Seagrasses, including manatee grass, are a favorite food, and these plants have evolved to accommodate grazing by manatees, turtles, waterfowl, and other animals. A 1,000-pound adult manatee eats up to 100 pounds of vegetation a day.