A petty officer is a non-commissioned officer in the navies of many countries. In the United States Navy, it is a pay grade of E-4 to E-9. Petty officers who are E-7 to E-9 are called Chief, Senior Chief, or Master Chief Petty Officers. Petty officers are managers for sailors that work for them. They are managed by officers and do work that they are told to do. Petty officers are often told to manage seamen and lower ranked petty officers.