title: How the bending kinematics of swimming lampreys build negative pressure fields for suction thrust.
abstract: Swimming animals commonly bend their bodies to generate thrust. For undulating animals such as eels and lampreys, their bodies bend in the form of waves that travel from head to tail. These kinematics accelerate the flow of adjacent fluids, which alters the pressure field in a manner that generates thrust. We used a comparative approach to evaluate the cause-and-effect relationships in this process by quantifying the hydrodynamic effects of body kinematics at the body-fluid interface of the lamprey, Petromyzon marinus, during steady-state swimming. We compared the kinematics and hydrodynamics of healthy control lampreys to lampreys whose spinal cord had been transected mid-body, resulting in passive kinematics along the posterior half of their body. Using high-speed particle image velocimetry (PIV) and a method for quantifying pressure fields, we detail how the active bending kinematics of the control lampreys were crucial for setting up strong negative pressure fields (relative to ambient fields) that generated high-thrust regions at the bends as they traveled all along the body. The passive kinematics of the transected lamprey were only able to generate significant thrust at the tail, relying on positive pressure fields. These different pressure and thrust scenarios are due to differences in how active versus passive body waves generated and controlled vorticity. This demonstrates why it is more effective for undulating lampreys to pull, rather than push, themselves through the fluid.
authors.affiliation: Department of Integrative Biology, University of South Florida, Tampa, FL 33620, USA.|The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA 02543, USA.
authors.forename: Brad J
authors.initials: BJ
authors.lastname: Gemmell
authors.affiliation: The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA 02543, USA.
authors.forename: Stephanie M
authors.initials: SM
authors.lastname: Fogerson
authors.affiliation: The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA 02543, USA.|Biology Department, Providence College, Providence, RI 02918, USA.
authors.forename: John H
authors.initials: JH
authors.lastname: Costello
authors.affiliation: The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA 02543, USA.
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: Morgan
authors.affiliation: Departments of Civil & Environmental Engineering and Mechanical Engineering, School of Engineering, Stanford University, Stanford, CA 94305, USA.
authors.forename: John O
authors.initials: JO
authors.lastname: Dabiri
authors.affiliation: The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA 02543, USA scolin@rwu.edu.|Marine Biology and Environmental Science, Roger Williams University, Bristol, RI 02809, USA.
authors.forename: Sean P
authors.identifier: 0000-0003-4463-5588
authors.initials: SP
authors.lastname: Colin
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D007798:Lampreys / Q000502:physiology*; D008954:Models, Biological; D011312:Pressure; D012399:Rotation; D013396:Suction; D013550:Swimming / Q000502:physiology*; D013623:Tail; D013997:Time Factors
keywords: Biomechanics; Fish; Flexible bending; Hydrodynamics; Propulsion; Vortex