with teeth for grasping slippery prey. Today,  Cormorants  (family Phalacrocoracidae ),  Loons  ( Gaviidae ), and  Grebes  ( Podicipedidae ) are the major groups of  foot  propelled diving birds. Wing-propelled diving birds Other diving birds are wing - propelled, most notably the  Penguins  ( Sphenisciformes ),  Dippers  ( Cinclus ) and