Date of Award

Fall 2007

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

Program/Concentration

Biology

Committee Director

Ian K. Bartol

Committee Member

Kent E. Carpenter

Committee Member

Daniel M. Dauer

Committee Member

Michael Vecchione

Call Number for Print

Special Collections LD4331.B46 S84 2007

Abstract

Although the pulsed jet is often the foundation of a squid's locomotive system, the lateral fins also play an important role in swimming, potentially providing thrust, lift, and dynamic stability. Fin morphology and movement vary greatly among squid species, but the locomotive role of the fins is not well understood. To begin to elucidate the locomotive role of the fins in squids, fin hydrodynamics were studied in the brief squid Lolliguncula brevis, a species that exhibits a wide range of fin movements depending on swimming speed. Individual squid were trained to swim in both the arms-first and tail-first orientations against currents in a water tunnel seeded with light-reflective particles. Particle-laden water around the fins was illuminated with lasers and videotaped so that flow dynamics around the fins could be analyzed using a technique known as digital particle image velocimetry (DPIV). Time-averaged forces generated by the fin were quantified from vorticity fields of the fin wake. During the low swimming speeds considered in this study (< 2.5 dorsal mantle lengths (DML) s-1), the squids exhibited four unique fin wake patterns, each with distinctive vortex ring structures: 1) a low speed mode in which one vortex is shed with each downstroke; 2) an undulatory mode in which a continuous linked chain of vortices is produced; 3) a third mode in which one vortex is shed with each downstroke and upstroke, and; 4) a final mode in which a discontinuous chain of linked double vortex structures are produced. All modes were detected during tail-first swimming but only modes 2 and 3 were observed during arms-first swimming. The fins produced horizontal and vertical forces of varying degrees depending on stroke phase, swimming speed, and swimming orientation. During tail-first swimming, the fins functioned primarily as stabilizers at low speeds before shifting to propulsors as speed increased, all while generating net lift. During arms-first swimming, the fins primarily provided lift with thrust production playing a reduced role. These results demonstrate the lateral fins are an integral component of L. brevis' complex locomotive system, producing lift and thrust forces through different locomotive modes.

Rights

In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).

DOI

10.25777/110d-gx43

Download

Share

COinS