Meeting Abstract

P3.64  Jan. 6  Pectoral swimming kinematics of the bay pipefish, Syngnathus leptorhyncus WINTERS-MIST, E*; HORTON, J.M.; FERRY-GRAHAM, L.A.; SUMMERS, A.P.; California State University, Long Beach; Univ. of California, Irvine; Moss Landing Marine Laboratories; Univ. of California, Irvine mistyewp@yahoo.com

The primary propulsive mechanism in syngnathids (e.g. seahorses, pipefish, and sea dragons) is thought to be the dorsal fin undulation. We observed that in addition to the dorsal fin undulation, pectoral fin oscillation plays an important and unusual role during swimming. We investigated the kinematics of the pectoral fins during three swimming modes in still water. Six pipefish (Syngnathus leptorhynchus) from three size classes (means 13.65, 18.25, and 29.95 TL) were filmed at 1000 frames/s moving forward, backward, or station holding. Eighteen video sequences were digitized in NIH Image J and used for analysis. Pectoral fin oscillation was 120��250� out of phase (mean 163�) during all swimming behaviors. In four sequences covering the range of behaviors, the pectoral fins were in synchrony an average of only 25% of the time during the bout. Fin beat frequencies were 19-41 Hz at an average swimming speed of 0.12 BL/s. There was a weak correlation between fin kinematics and swimming speed (BL/s); fin frequency: left fin R2 = 0.275, right fin R2 = 0.177; fin velocity: left fin R2 = 0.113, right fin = 0.094. No significant differences were detected between the kinematics of right and left fins, thus the data were pooled for examining kinematic patterns associated with locomotion type. There was a strong correlation between fin velocity and amplitude for forward, holding, and backward behaviors (R2 = 0.834, R2 = 0.946, R2 = 0.828, respectively). Due to the highly variable degree of syncopation, we concluded that the pectoral fins are primarily used for stability and maneuvering.