Collaborative Research: IOS:RUI: Hydrodynamic consequences of spines on zooplankton: Functional morphology of horns and tails on barnacle nauplii

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Zooplankton, small animals that drift with ocean currents, are critical links in marine food webs. Many different types of zooplankton have elongated spines, horns, or hairs. These structures are thought of as predator deterrents or sensory antennae. This project examines other ecologically important functions that spines might impact: feeding, swimming, sinking, and dislodgement from surfaces. These functions depend on how animals interact with the water around them. This study investigates how spines work to alter the movement of the surrounding water and how that water movement varies in the early development of the “nauplius” larval stage of different species of barnacles. Barnacles are a type of crustacean, a group that includes the commercially important crabs, shrimp, and lobsters. Since all crustaceans have a nauplius larval stage, this research will shed light on how this common body form operates, providing information about functional tradeoffs between different behaviors and body shapes. This project -- a collaboration between a small, liberal arts undergraduate college and a big research university -- brings together students and faculty from both to conduct the research and to train undergraduates. In addition, this project crosses disciplinary boundaries between biology and engineering, so students from different fields will learn how to communicate and collaborate. Principles discovered from this study can inform bio-inspired design of aquatic microrobots. The types of experiments designed will also be used to develop new science curricula. Diverse zooplankters bear spines with functions that are poorly understood. This study of the hydrodynamics of different species of barnacle larvae will determine (1) functional consequences of the presence, location, and morphology of spines on hydrodynamic forces and torques; (2) functional consequences of spines and appendage kinematics on the forces and torques generated, and on swimming, sinking, and feeding performance; and (3) hydrodynamic consequences of the change in body design from the planktonic nauplius to the settling cyprid form. Kinematics and flow fields of larvae with distinctive morphologies and ecology are measured using micro-videography and high-speed particle image velocimetry. This comparative study on live organisms is coupled with experiments using dynamically scaled physical models to determine mechanisms by which specific features control forces and torques on, and flow fields around, larvae. Physical models allow parameters – spine size and shape; body size and shape; limb morphology; and kinematics -- to be varied in ways not possible with living organisms. In addition to elucidating general principles about the hydrodynamic consequences of spines at the poorly understood size and speed range of zooplankton – the domain of intermediate Reynolds numbers -- the project will advance understanding of how tradeoffs between ecological functions impose biomechanical constraints that can shape the evolution of form. Collaboration between a PUI college and R1 university integrates research and undergraduate education at both. The question-driven, experience-based learning approach involves research teams of undergraduates from physical and biological sciences to develop their skills at interdisciplinary collaboration. Novel interdisciplinary course materials will be developed with context-rich modules for teaching quantitative skills.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.