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Fig. 9. Detailed kinematics of the body and fluke during four consecutive lateral
lunges at depth. The kinematic parameters presented over time include fluking
dynamics (orange), acceleration (green) and speed (purple) of the body, and
body pitch (red) and roll (blue). Fluking is derived from the small-scale,
dynamic oscillations in the accelerometer signals. Dynamic acceleration values
are presented with negative peaks pointing up and positive peaks pointing down
to intuitively show upstrokes and downstrokes of the fluke, respectively (see
Materials and methods for explanation). Instantaneous speed of the body is
estimated from the magnitude of flow noise measured by the hydrophone. Body
orientation is resolved in two dimensions from the changes in static
acceleration along two orthogonal axes. Associated maxima (filled circles),
minima (open circles) and zero values (crosses) of each kinematic parameter
are superimposed onto the dive profile in the upper panel to illustrate the
temporal coordination of rotational torques with translational accelerations.
The onset of body acceleration and rotation are coincident with each fluking
bout. The body becomes level prior to each lunge. Jaw opening is assumed to
take place at maximum speed (3.0±0.5 m s–1;
N=62; purple circles). Fluking continues after maximum velocity
occurs. Maximum body deceleration and roll maxima (87±18°;
N=62) occur concomitantly (open green circle and filled blue circle).
The kinematic sequence is completed as the body reaches its minimum speed and
comes to a maximum pitch angle.
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