Adult suspension feeding fishes (e.g., anchovies and mackerels) capture multiple prey by swimming with mouths held open. Despite the economic and ecological importance of these fishes, few studies have tested hypotheses concerning the functional morphology, energetics, and hydrodynamics of suspension feeding. As juveniles, these species are particulate feeders that capture individual prey using suction. The profound shift from particulate feeding to suspension feeding offers an ideal opportunity to investigate suspension feeding from a mechanistic perspective. The techniques of respiratory physiology and biomechanics will be applied to test two main hypotheses: first,that the hydraulic resistance of the water path through the oral and opercular cavities, as well as the hydrodynamic drag of the entire body during swimming with the mouth held open, is significantly higher in juvenile blackfish than in adults; and secondly, that the energetic cost of feeding decreases abruptly over the transition between feeding modes. Although the energetic cost of suspension feeding may be low after the transition, physical constraints may prevent juveniles from suspension feeding. Information on the factors involved in the switch between feeding modes will have implications for plankton population dynamics, resource partitioning between juvenile and adult fishes, and the evolution of suspension feeding in fishes. The University of California at Davis will serve as the host institution for this postdoctoral research fellowship project. The duration of this award is two years.
