Meeting Abstract
Copepods are among the most evasive prey in the plankton. These small crustaceans have sensitive mechanoreceptors to detect approaching predators, and perform high-speed escape jumps to avoid being eaten. Nevertheless, copepods are the preferred prey for many larval fishes, providing an important food source throughout the planktonic phase of reef fish development, from first feeding to settlement. During this critical life-history stage larval fish must acquire the ability to successfully capture these evasive prey. To investigate how behavior of predator and prey shape the outcome of their interactions, we studied larval clownfish, Amphiprion ocellaris, feeding on the copepod, Bestiolina similis. Predator-prey interactions were recorded with a high-speed camera configuration designed for manually following individual fish larvae to observe feeding events. Fish from day 1 post-hatch (first feeding) to day 14 post-hatch (end of larval stage) were fed copepods of different life stages. The copepods’ sensory-motor escape performance improved with developmental stage, from nauplii to adults. At first feeding, A. ocellaris only successfully captured B. similis nauplii, but were unable to capture copepodites or adults. On day 7 post-hatch, larval fish were first observed attacking adult copepods but with limited capture success. By day 14 post-hatch, A. ocellaris were capable of successfully capturing all life stages of copepod prey. The differences between successful captures and successful escapes were characterized using frame-by-frame video analysis to measure strike distance, velocity, acceleration, and orientation. Since the gape width of the clownfish mouth can accommodate adult copepods as early as day 2 post-hatch, we suggest behavioral dynamics shape the diet of these larval fish.
