1,    a,    adults,    animals,    artiodactyl,    Artiodactyla,    format,    gape,    gapes,    Hippopotamus,    hippos,    humour,    humourous,    laterally,    mammals,    menacing,    move,    movement,    moves,    open,    outdoors,    outside,    river,    riverhorses,    solo,    swimming,    swims,    threatening,    threats,    yawn,    yawns,