SUMMARY

The focus of this thesis is to investigate the hydrodynamics of “multi-oar” propulsion at intermediate flow regimes via studying the appendage locomotion in several aquatic organisms. Tomographic Particle Image Velocimetry (tomo-PIV), a robust flow visualization technique, is used to quantify and compare the hydrodynamics of swimming behavior of several species of free-swimming planktonic malacostracan crustaceans, which are seldom-studied but highly maneuverable organisms. This work successfully investigates the hydrodynamics of locomotion of two planktonic crustaceans that are essential in marine ecosystems, Antarctic krill and mysid shrimp, to contribute to the understanding of zooplankton locomotion behavior and flow characteristics of intermediate flow regimes. The first portion of this study investigates the hydrodynamics of the crustacean fast start mechanism, i.e. the caridoid response, as performed by the free-swimming planktonic crustacean, the Antarctic krill. The second study reports on the 3D hydrodynamics of fast forward and upside-down swimming in Antarctic krill. The last study investigates the hydrodynamics of metachronal propulsion in mysid shrimp. Understanding the hydrodynamics of zooplankton locomotion leads to an increase in knowledge in three aspects. Planktonic crustaceans are a critical component of marine ecosystem. Hence, understanding more about the hydrodynamics of their locomotion, which involves, feeding, mating, migration, predator avoidance, and swimming behavior, allows for more accurate information available for ocean model prediction and marine ecosystem health. Understanding the hydrodynamics of locomotion in planktonic crustaceans also allows for a more well-rounded understanding of fundamentals of fluid mechanics in the intermediate flow regime. Finally, understanding the flow characteristics of paddling in aquatic organisms would be helpful in creating more efficient bio-inspired multi-limb underwater robotic designs. This study begins to answer some fundamental questions surrounding drag-based propulsion mechanisms, metachronal propulsion of freely moving organisms in aquatic environments, and the flow characteristics of intermediate flow regimes by quantifying the volumetric flow of various planktonic crustacean species.