Escape strategies in co‐occurring calanoid copepods

We show how four co‐occurring calanoid copepod species modulate their responses to two contrasting hydrodynamic stimuli. Species‐specific patterns in escape behavior included quantitative differences in performance to each stimulus type. Using high‐speed video, we compared escape reactions in Acartia hudsonica, Centropages hamatus, Tortanus discaudatus, and Temora longicornis. Responses to a flow field created by a suction tube involved reorientation away from the source of suction followed by a series of vigorous power strokes. Responses to brief computer‐controlled hydrodynamic stimuli had short latencies (a few milliseconds) and consisted of a reorientation followed by a few pereiopod power strokes. Two species responded to this stimulus with higher escape speeds. The other two species gave a larger response to the suction stimulus by producing long escape trajectories. Each species perceived the magnitude of the threat in a different way and employed a different strategy in the escape response.