'Robotuna' makes a splash.

The tuna is a highly maneuverable long-distance swimmer that evolved over 160,000,000 years. In just three years, though, Massachusetts Institute of Technology students, led by Michael Triantafyllou, professor of ocean engineering, have succeeded in building a robot version that will lead to better, faster boats.

The "Robo Tuna" project began as a search for a better propulsion system for small robotic submarines or AUVs--autonomous underwater vehicles--that map the ocean floor, seek out sources of underwater pollution, and perform other tasks. Currently, however, they can remain underwater for limited amounts of time, which restricts their usefulness. "You simply can't put enough batteries on board for long-term missions," explains David Barrett, a graduate student in ocean engineering who is developing the robotic fish for his doctoral thesis. Extreme constraints on energy storage demand propulsors more efficient than those now used. To that end, Triantafyllou and his students looked to nature's own aquatic residents in the hope of mimicking their efficiency--a branch of science known as biomimesis.

The first prototype, originally nicknamed "Charlie the Testing Tank Tuna," is approximately four feet long and resembles the real thing as closely...