150416-M-YH418-023: GULF OF ADEN (April 16, 2015) – Petty Officer 1st Class Petronilo Marcelo, center, a hospital corpsman and independent duty corpsman with Combat Logistics Battalion 24, 24th Marine Expeditionary Unit, instructs Iwo Jima Amphibious Ready Group Sailors on triaging a casualty during a mass casualty exercise aboard the amphibious transport dock ship USS New York (LPD 21), April 16, 2015. The 24th MEU is embarked on the ships of the Iwo Jima Amphibious Ready Group and is deployed to maintain regional security in the U.S. 5th Fleet area of operations. (U.S. Marine Corps photo by Cpl. Todd F. Michalek/Released)