gills are used for breathing water by aquatic animals
all_fish has gills aquatic_ecosystem is water. waterfowl is aquatic_bird. fish has not gills_which_allow_breathing_water fish has gills immature_amphibians has gills fish is aquatic_animal. all_fish_breathe_water_and has not gills all_fish_breathe_water_and has gills fish has gills_which_allow_breathing_water