P3.134 Friday, Jan. 6 Kinematics and fluid dynamics of pectoral fin movement in larval zebrafish. GREEN, MH*; CURET, OM; PATANKAR, NA; HALE, ME; Univ. Chicago; Northwestern Univ.; Northwestern Univ.; Univ. Chicago email@example.com
Larval zebrafish rhythmically beat their pectoral fins during many behaviors including low speed swimming, prey tracking and hovering; however, very little is known about the functions of larval pectoral fin movements. We used high-speed video imaging to track the movement of the pectoral fins during slow forward swimming. We observed large bending along the span of the fin during abduction. During adduction the fin remained rigid along its span. We placed drops of dye in the water to image the movement of fluid by the fins. Dye-marked fluid was transported by fin beats from a position rostral and lateral to the fin base to a position caudal to the fin base near the body surface. Dye-marked fluid appeared to be stretched, folded and pushed backwards by fin beats. We used computational fluid dynamics to analyze the fluid dynamics of normal fin movement, and to test the effects of removing bending from the fin motion. For normal fin beats, we found a qualitative match between simulated fluid movement and fluid movement observed during dye imaging experiments. Patterns of stretching and folding of fluid by the fin were found to correspond to Lagrangian coherent structures (LCS) in the fin wake. When bending was removed from fin motion, fins were less effective at transporting fluid to the body surface, and the LCS in the fin wake were disrupted. Our data suggest that the pectoral fins are effective in transporting distant fluid to the body surface and mixing fluid near the body surface, and that bending along the span of the fin during abduction is essential for transport and mixing.