Meeting Abstract

13.2  Monday, Jan. 4  Rowing with Multiple Appendages in Stomatopod Crustaceans: Beyond Single Paired Appendages CAMPOS, E. O.; University of Washington, Seattle eocampos@u.washington.edu

Unsteady fluid dynamic forces are crucial components of the mechanisms underlying propulsion at high Reynolds numbers, including motion with undulating surfaces or rowing appendages. An understanding of the emergent wake structures should provide validation of theoretical estimates of these mechanisms. Time-dependent hydrodynamic forces derive from momentum imparted to the fluid medium, manifested as vortex structures which can be visualized and quantified. Flapping and rowing have received considerable attention in a comparative context since they are viewed as two extremes along a continuum of appendage reciprocation. These analyses have focused almost exclusively on rowing and flapping of a single pair of appendages for locomotion. However, many animals row by reciprocating multiple appendages arranged serially along the anteroposterior axis, as in many crustaceans and polychaetes. Stomatopod crustaceans take this type of rowing to the extreme, employing it to achieve escape swimming speeds of over 30 body lengths per second (BL/s). Individual Odontodactylus havanensis (35-64 mm total length) were filmed at 60 and 500 frames per second (fps) and tracked with position-tracking software. Visual examination of individual frames confirms that stomatopods can reach and exceed 30 BL/s, with a peak velocity of 35.8 BL/s. Stroke frequencies exceeded 16 Hz. Such rapid appendage accelerations point to significant added mass effects or other unsteady phenomena. Studying the fluid wake patterns generated by different coordination schemes may yield interesting results that could enhance our understanding of animal locomotion. Stomatopod swimming provides a model system for studying the rowing mechanics of multiple paired appendages.