Ducks lay eggs once a year and are omnivorous, eating aquatic plants and tiny animals. Dabbling ducks feed on the surface of water or on land, or as deep as they can reach by up-ending without completely submerging. Along the edge of the beak there is a comb-like structure called a "pecten". This strains the water squirting from the side of the beak and traps any food. The pecten is also used to preen feathers. Diving ducks dive deep to get their food.