Kinematic characteristics of calanoid copepod appendage motion

Abstract

Abstract Propulsion by copepods requires high-speed video and intensive analyses. Routine smooth swimming is compared with small relocation jumps and escape reactions, relying on kinematics analyses of appendage movement. In this study, we used high-speed video at 1200 frames per second to determine the kinematic parameters of three types of swimming in Eurytemora affinis females: routine steady swimming, small relocation jumps and escape reactions. The average speed varied in the range 0.30–0.82 cm s−1 during steady routine swimming. This value increased to 4.48 ± 1.01 cm s−1 during small relocation jumps, and reached 21.94 ± 2.68 cm s−1 during escape reactions. The small angular amplitude (40–50°) and the very high beat frequency (63–80 Hz) of the cephalic appendages during routine swimming indicate that E. affinis is a feeding-current feeder. The comparison of the angular displacements of the antennules, thoracic legs and abdomen with respect to the movement speed demonstrates that, both in the case of small relocation jumps and during escape reactions, the main propulsive role is played by the thoracic swimming legs and abdomen.