Kinematic characteristics of calanoid copepod appendage motion.

This article focuses on the kinematic analysis of three swimming modes—routine steady swimming, small relocation jumps, and escape reactions—in females of the calanoid copepod *Eurytemora affinis*. Using high-speed video recordings at 1200 frames per second, the study demonstrates that steady swimming is driven by high-frequency, small-amplitude movements of cephalic appendages (antennae and mandibles), consistent with a feeding-current feeding strategy. In contrast, both relocation jumps and escape responses rely primarily on the metachronous strokes of thoracic swimming legs and abdomen, with escape reactions exhibiting significantly higher speeds and shorter durations. The findings clarify that the first antennae (antennules) contribute minimally to propulsion during jumps, serving mainly for stabilization, and highlight differences in appendage coordination between swimming modes, providing insights applicable to other calanoid copepods.