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Foraging behaviour of six calanoid copepods: observations and hydrodynamic analysis

Swimming behaviour is described for 6 small copepods. Three types of feeding strategies were observed: (1) slow-moving or stationary suspension feeding (Ternora longicornis, Pseudocalanus elongatus, and Paracalanus parvus); (2) fast swimming interrupted by sinking periods (Centropages typicus and C. hamatus); (3) motionless sinlung combined with short jumps (Acartia clausi). Flow fields were similar for all suspension-feeding species but the anterior velocity gradient moved closer to the copepod in fast-swimming species. Theoretical hydrodynamic models were used to investigate costs and benefits of the different feeding strategies. Stationary suspension feeding is most efficient for capture of non-motile prey (algae) and fast swimming or sinking is better for capture of moving, rheotactic prey. Escape reaction distance of prey was calculated from theoretical models and from observed escape patterns of nauplii. Feeding behaviour is suggested as an important factor for prey selectivity of copepods.