First published online November 30, 2007
Journal of Experimental Biology 210, 4379-4389 (2007)
Published by The Company of Biologists 2007
doi: 10.1242/jeb.009787
Routine turning maneuvers of koi carp Cyprinus carpio koi: effects of turning rate on kinematics and hydrodynamics
Guanhao Wu1,*,
Yan Yang2,3 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
3 Department of Modern Mechanics, University of Science and Technology of
China, Hefei 230026, China

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Fig. 1. The coordinate system and notation used to describe the kinematics and the
wake of the fish. Two counter-rotating circles represent a pair of vortices.
The bold arrow indicates the jet flow. The dotted line indicates the body axis
of the carp at the onset of a turn. The broken lines are auxiliary lines. See
text for more details and List of symbols and abbreviations for
definitions.
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Fig. 2. Frequency distributions of the routine single-beat turns in the four
turning categories. Open bars, turns with type I wake; filled bars, turns with
type II wake. The sum of the two bars represents the total number of turns in
each category.
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Fig. 4. Representative flow patterns of wake type I. Black arrows represent flow
velocity magnitude and direction, and vortices are numbered. Vorticity is
shown in color in the background. (A–F) Evolvement of vorticity and flow
velocity vector fields at different times during the turn.
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Fig. 8. (A) Scatter plot of the recoil speed of the tail in stage 2 against the
mean turning rate in stage 1 ( 1). Filled circles, turns with
type I wake; open circles, turns with type II wake. (B) Scatter plot of the
momentum of the vortex ring shed in stage 2 (I2) against
the recoil speed of the tail in stage 2. (C) Linear regression of
I2 against the bending amplitude
(dmax).
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© The Company of Biologists Ltd 2007