Modulation of buccal pressure during prey capture in Hexagrammos decagrammus (Teleostei: Hexagrammidae)

Changes in intraoral pressure during prey capture were recorded for a trophic generalist, Hexagrammos decagrammus, feeding on different prey species. Prey were grouped into elusive (shrimps), grasping (isopods and crabs) and non-elusive (pieces of shrimp) categories. Elusive and grasping prey elicited strikes with a larger and faster reduction in buccal pressure than did non-elusive prey. The suction force generated by the predator differed for strikes among the shrimp genera in the elusive prey category. The most sedentary shrimps (Crangon alaskensis and C. nigricauda) elicited the fastest and greatest reduction in pressure relative to the most evasive shrimps (Pandalus danae and Heptacarpus stylus). A preparatory phase, during which the buccal cavity is compressed prior to the strike, occurred significantly more frequently in strikes at grasping prey than in strikes at elusive and non-elusive prey, and more frequently for elusive than for non-elusive prey. Prey size did not influence the suction force generated by the predator. No differences in buccal pressure patterns were detected between strikes that resulted in a capture or a miss, suggesting that misses were due to the escape behavior of the prey and were not the result of an inappropriate suction force. These data support the current view that fish can modify their feeding mode in response to prey behavior, and they emphasize that the behavioral responses of the individual prey must be considered when defining the appropriate strategy for prey capture. The use of a flexible, modifiable feeding behavior is associated with a broad diet in H. decagrammus and may increase capture success on diverse prey relative to that of other species showing stereotypical feeding responses.