Mechanical Determinates of Crustacean Escape Swimming

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The research revolves around two approaches to understanding the physical determinants of motility. One approach examines the physics of propulsion from an engineering standpoint. Forces generated by appendage movements are used to estimate thrust and body trajectories for a variety of situations, including aerial, aquatic, and terrestrial locomotion. A goal is to determine what motions and body morphologies are feasible for accomplishing certain movements such as flight, swimming, or running and the limitations to movements in terms of design and energetics. A second approach centers upon the physiology of the muscles that generate locomotor movements. A number of important limitations to muscle contractility have been shown with the maxima for force and the inverse relationship between the force and velocity of contraction both etermining overall muscle and appendage motions. While both above approaches have yielded fruitful insight into the limitations to animal motility, no previous study has explicitly linked these two components. Daniel proposes to combine these two areas to determine both physical and physiological limitations to one extreme mode of locomotion: escape from predation. We use a local species of shrimp, Pandalus danae, that exhibits an escape motion involving a rapid flexion of the abdomen that lasts approximately 30 ms. The hydrodynamics of this mode of locomotion has already been worked out. He has shown that both the size and shape of these animals are constrained by the dynamics of accelerational locomotion. He proposes to address basic questions regarding these and related contractile systems: (1) What are the forces generated by such rapidly contracting muscles (2) How do active and inactive antagonistic muscle groups respond to such rapid extensions? and (3) How is this activity regulated and transferred into productive motility.