Aquatic Sciences Meeting, Albuquerque 2001

SS15 Biomechanics: Making the Connection Between Physics and Biology at the Organismal Level (Disciplinary Connections)

Date: Wednesday, February 14, 2001, Time: 2:45:00 PM

Location: Mesilla

McHenry, M, J, U.C. Berkeley, Berkeley, USA, mchenry@socrates.berkeley.edu

The hydrodynamics of intermediate Reynolds number swimming in ascidian larvae (Botrylloides sp.)

Despite recent advances in computational modeling and flow visualization, the hydrodynamics of swimming animals remains a subject of debate. This is certainly the case for undulatory swimmers operating at intermediate Reynolds numbers (Re), where both inertial and viscous forces are important. In the present study, propulsive forces were measured in swimming ascidian ‘tadpole’ larvae (Botrylloides sp.), which swim at Re~100. These 2mm long larvae were tethered to micro-capillary tubes with light suction. By measuring the stiffness of this tether, the total force generated by the larval body was calculated from tether deflection measurements. Forces measured in tethered larvae were greatest in the lateral direction and were found to vary between 1 and 40 μN among individuals. These measurements were compared to theoretical predictions for lateral forces by applying blade element methods to the axial kinematics of the tail. These measurements will provide the basis for a more comprehensive treatment of the dynamics of helical swimming in larvae of ascidians and other marine invertebrates.

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Aquatic Sciences Meeting, Albuquerque 2001

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