Meeting Abstract
83.4 Thursday, Jan. 7 Form, function and flow in the plankton: Jet wake structure and swimming performance of pelagic tunicates SUTHERLAND, K. R.*; MADIN, L. P.; MIT/WHOI Joint Program in Oceanography; Woods Hole Oceanographic Institution krakow@whoi.edu
Salps are barrel-shaped marine invertebrates that swim by jet propulsion. Morphological variations among species and life-cycle stages are accompanied by differences in swimming mode. The goal of this investigation was to compare propulsive jet wakes and swimming performance variables among morphologically distinct salp species (Pegea confoederata, Weelia (Salpa) cylindrica, Cyclosalpa affinis) and relate swimming patterns to ecological function. Using a combination of in situ dye visualization and particle image velocimetry (PIV) measurements, we described properties of the jet wake and swimming performance variables including thrust, drag and propulsive efficiency. Locomotion by all species investigated was achieved via vortex ring propulsion. We found that the slow-swimming P. confoederata produced the highest weight-specific thrust (T= 53 N kg-1) and swam with the highest whole-cycle propulsive efficiency (ηwc= 55%). The fast-swimming W. cylindrica had the most streamlined body shape but produced an intermediate weight-specific thrust (T= 30 N kg-1) and swam with an intermediate whole-cycle propulsive efficiency (ηwc= 52%). Weak swimming performance variables in the slow-swimming C. affinis, including the lowest weight-specific thrust (T= 25 N kg-1) and lowest whole-cycle propulsive efficiency (ηwc= 52%), may be compensated by low energetic requirements. Swimming performance variables will be considered in the context of ecological roles and evolutionary relationships.
