Review of fish swimming modes for aquatic locomotion

Several physico-mechanical designs evolved in fish are currently inspiring robotic devices for propulsion and maneuvering purposes in underwater vehic les. Considering the potential benefits involved, this paper presents an ov erview of the swimming mechanisms employed by fish. The motivation is to pr ovide a relevant and useful introduction to the existing literature for eng ineers with an interest in the emerging area of aquatic biomechanisms, The fish swimming types are presented, following the well-established classific ation scheme and nomenclature originally proposed by Breder, Fish swim eith er by body and/or caudal fin (BCF) movements or using median and/or paired fin (MPF) propulsion. The latter is generally employed at slow speeds, offe ring greater maneuverability and better propulsive efficiency, while BCF mo vements can achieve greater thrust and accelerations, For both BCF and MPF locomotion, specific swimming modes are identified, based on the propulsor and the type of movements (oscillatory or undulatory) employed for thrust g eneration. Along with general descriptions and kinematic data, the analytic al approaches developed to study each swimming mode are also introduced. Pa rticular reference is made to lunate tail propulsion, undulating fins, and labriform (oscillatory pectoral fin) swimming mechanisms, identified as hav ing the greatest potential for exploitation in artificial systems.