Flow Dynamics in the Oral and Opercular Cavities of the American Shad (Alosa sapidissima)

The American shad (Alosa sapidissima) is hypothesized to use crossflow filtration, with the gill rakers as the filter surface. Image analysis and data mining techniques were used to analyze the general pattern of water flow in the oral and opercular cavities of the shad and quantify the exit areas, not done previously for the entire branchial basket. The flow patterns, as well as particle retention in the shad at extreme yaw angles, suggest that crossflow filtration occurs in the shad. The flow patterns discovered in this study may assist in the further development of bioinspired filtration systems for industrial use, as well as raise questions surrounding the evolution and functional morphology of the gill rakers.