Unrecognized Passive Controls of Posture and Trajectory in Many Actively Swimming Aquatic Animals

摘要

Greater control of movements gives actively swimming aquatic animals greater abilities to move as necessary. Control mechanisms affect posture, swimming trajectory, static and dynamic stability, and maneuverability. Control mechanisms are both passive and powered. This paper focuses on an unrecognized set of passive mechanisms of control of posture and trajectory that occur in a wide variety of actively swimming aquatic animals. We discuss insights concerning passive mechanisms of control deriving from our earlier work with tetraodontiform fishes that we think also apply much more widely. Detailed consideration is given to possible roles of lateral keels and rows of scutes located on and near the caudal peduncles in many different elasmobranchs (sharks) and bony fishes, also to the peduncular keels found in all cetaceans. Similar structures in some fossil aquatic forms are also discussed.