Small, medium or large, a robotic fish maintains its swimming ability

Propeller-powered underwater vehicles have long helped scientists explore and monitor aquatic environments. But they're limited by their own mechanics: spinning blades can snag on vegetation, stir up sediment, and startle the wildlife they're often sent to study, making them poorly suited to shallow creeks, dense weeds, or close encounters with fish. That's one reason roboticists have spent years building machines that swim like fish instead, bending their bodies rather than spinning a propeller. The catch is that most fish-inspired robots are built for one size and one job, so scaling them up or down usually means starting from scratch. A team of engineers at EPFL and New York University (NYU) says it has found a way to solve that problem.