Meeting Abstract

P1.115  Tuesday, Jan. 4  Attitude is Everything: Extending models of fish kinematics to maneuvers VERHEGGEN, Heidi*; GENG, Liusha; ROOT, Robert; Lafayette College; Lafayette College; Lafayette College verheggh@lafayette.edu

A primary component of studying fish locomotion is quantifying locomotor kinematics for a wide variety of undulatory swimming behaviors among various fish species. One approach we have found fruitful is to describe the harmonic structure of these kinematics. In this study, we obtain such a description by improving on an existing model to better capture periodic components of various forms of locomotion. Both old and new models are based on video data reduced to midline position for various species: hagfish, lamprey, and shark, in various locomotive states, including constant-speed swimming and turning. To improve undulatory frequency estimation, a statistical technique involving the Hilbert transform was devised to extract a fundamental frequency associated with data for a given video clip. Applying this technique yields a more general and consistent estimate of the period of midline motion, addressing a central challenge of modeling unsteady swimming. The frequency estimates are notably consistent along the body in all trials, and surprisingly show the least variation for a turning shark, showing that this approach adapts our model to analyze maneuvers. In addition, the model of midline kinematics is greatly simplified: by using attitude data—the angle of body segments—rather than position data, the number of fitting parameters is reduced by nearly a factor of one half, and the data is more appropriately fitted using least absolute residual regression rather than least-squares. Thus, with the reconstruction techniques we have developed, the analytical process presented here yields an accurate, quantitative description enabling a better understanding of locomotor kinematics.