Reaction times and force production during escape behavior of a calanoid copepod, Undinula vulgaris

Effective escape behavior contributes to the success of copepods in plankto nic communities. The kinematics of escape were studied in tethered Undinula vulgaris (Calanoida) by analyzing the timing and magnitude of their power strokes to a precisely controlled, sudden mechanical perturbation in the su rrounding water. Copepods responded with rapid swims to water velocities of 36 to 86 mu m s(-1). Reaction times were under 2.5 ms following stimulus o nset. The time course of force exerted was complex, but reproducible from s timulus to stimulus. Multiple power strokes ("kicks'') were frequently obse rved in response to single stimuli. Time intervals of 5 ms were observed be tween the end of one escape kick and the beginning of the next. U. vulgaris developed maximum forces of 40 to over 100 dynes (dyn) during a rapid swim . The behavioral reaction times and intervals between multiple responses ob served in this calanoid are among the shortest reported in aquatic inverteb rates.