The U.S. Department of Homeland Security says it\'s developing a \"robotic tuna\" to search and inspect constricted and hard-to-reach underwater places. Modeled on real tuna, some of the fastest and most maneuverable creatures on the planet, the robotic BIOSwimmer is designed for high maneuverability in harsh environments, with a flexible aft section and appropriately placed sets of pectoral and other fins, the department\'s Science and Technology Directorate reported Wednesday. Overcoming some of the propulsion and maneuverability problems that plague conventional unmanned underwater vehicles, BIOSwimmer is designed to inspect the interior voids of ships such as flooded bilges and tanks, and hard to reach external areas such as steerage and propulsion areas. It can also inspect and protect harbors and piers, perform area searches and carry out other security missions, its designers said. \"It\'s designed to support a variety of tactical missions and with its interchangeable sensor payloads and reconfigurable operator controls, can be optimized on a per-mission basis,\" said Mike Rufo, director of the Advance Systems Group of the Boston Engineering Corp., which is developing the BIOSwimmer for the Science and Technology Directorate. BIOSwimmer is battery-powered and designed for long-duration operations using an on-board computer for navigation, sensor processing and communications.