Meeting Abstract

13.1  Monday, Jan. 4  Locomotory kinematics of the pteropod Limacina helicina YEN, J*; CHANG, Y; , ; Georgia Tech, Atlanta; Georgia Tech, Atlanta; jeannette.yen@biology.gatech.edu

Limacina helicina is a thecosome pteropod that exists exclusively in the plankton, where swimming as well as other buoyancy mechanisms are required to offset the weight of its shell. When not feeding, swimming is employed for predator evasion and migratory purposes. Kinematic analyses of shipboard records of locomotion in 3D and fluid flow generated by 1-3 mm L. helicina revealed a distinctive swimming movement that propels the body in a radial axis, pitching negatively and positively during the stroke cycle. Swimming episodes included straight trajectories the majority of the time along with helical paths. Swimming individuals rotated their bodies to move in a mean vertical direction upwards followed by instances of straight descents. The wing stroke is a complex, three-dimensional motion with elements of rowing and flapping as well as rotation. Its erratic flight pattern is brought about by an asymmetry in the shell that manifests itself as an asymmetry between the left and right angular wing displacements. Mean speeds varied from 13-44 mm s-1 for straight ascents to a little higher for helical paths. Sinking speeds were 5-45 mm s-1 whereas wing beat frequencies decreased with size from 4.5-9.4 Hz. Living in a Re range between 20-100, this pelagic pteropod exhibits a fascinating mode of locomotion.