Koi Swimming Behavior Pattern

Burst-and-coast swimming patterns. I’m sure hobbyists have noticed this, but who thought to call it this?

Kinematics, hydrodynamics and energetic advantages of burst-and-coast swimming of koi carps (Cyprinus carpio koi)

Guanhao Wu^1,*, Yan Yang² and Lijiang Zeng¹

¹ State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments, Tsinghua University, Beijing 100084, China
² The Laboratory for Biomechanics of Animal Locomotion, Graduate University of Chinese Academy of Sciences, Beijing 100049, China/Department of Mechanics and Mechanical Engineering, University of Science and Technology of China, Hefei 230026, China

^* Author for correspondence (e-mail: tophow99@mails.tsinghua.edu.cn)Accepted 14 March 2007

Koi carps frequently swim in burst-and-coast style, which consists of a burst phase and a coast phase. We quantify the swimming kinematics and the flow patterns generated by the carps in burst-and-coast swimming. In the burst phase, the carps burst in two modes: in the first, the tail beats for at least one cycle (multiple tail-beat mode); in the second, the tail beats for only a half-cycle (half tail-beat mode). The carp generates a vortex ring in each half-cycle beat. The vortex rings generated during bursting in multiple tail-beat mode form a linked chain, but only one vortex ring is generated in half tail-beat mode. The wake morphologies, such as momentum angle and jet angle, also show much difference between the two modes. In the burst phase, the kinematic data and the impulse obtained from the wake are linked to obtain the drag coefficient (C_d,burst0.242). In the coast phase, drag coefficient (C_d,coast0.060) is estimated from swimming speed deceleration. Our estimation suggests that nearly 45% of energy is saved when burst-and-coast swimming is used by the koi carps compared with steady swimming at the same mean speed.

http://jeb.biologists.org/cgi/content/abstract/210/12/2181

~ by koinewsnetwork on November 28, 2007.