Not Just Going with the Flow

Aquatic animals can modify their fluid environment to improve efficiency

Frank Fish, George Lauder

Aquatic animals may seem to slip along with the prevailing currents, but many have developed body structures that allow them to actively manipulate their fluid environments. Water is an incompressible substance, so moving through it requires a lot of energy, and optimizing that flow can help animals conserve resources. Fish and Lauder use high-tech visualization techniques to study the active and passive mechanisms marine creatures employ, from body dimples to slime, to reduce drag. Animals can recapture energy from their compatriots by slaloming on their wakes. But marine inhabitants must also balance their stability in the water with their maneuverability, and the authors discuss special structures on whales and other creatures that aid in this endeavor. Their work may also lead to future autonomous underwater vehicles that have improved performance.