Fish have an extraordinary array of different body shapes. Some are highly streamlined and torpedo shaped; others are flattened and tall. It seems likely that some body shapes are better for swimming fast, others might be more maneuverable, and others might be more stable. It has been difficult to make these connections, however, because the internal mechanics of fish bodies also differ. Some are relatively stiff; others are very flexible. In this project, a group of fishes with different body shapes will be studied as they swim in water with eddies or other complex flow patterns. Their body movements and muscle activity will be recorded, which will allow their stability and efficiency to be measured. Then, based on the experiments, a computer model will be developed to simulate both the water movement and the flexible bodies of the fishes. The computer model can describe what might happen if the body shapes or body mechanics change. The model will be released for other researchers to use on similar problems, and the results will help in the design of better underwater vehicles and robots made out of flexible materials. In one educational component, science graduate students will be trained to communicate science better, coordinating with the Tufts STEM ambassadors program to reach out to local middle and high schools. Finally, an interactive museum activity at the Boston Museum of Science will be developed. The activity will allow museum visitors to design their own flexible fish and race it while measuring its efficiency.
In this project, the connection between swimming performance and body morphology, internal mechanics, and behavior will be investigated in related groups of fishes that differ in overall body shape. The dynamical properties of the body, including stiffness and damping, will be measured, with the muscles passive and active. Based on these measurements, a 3D computational model will be developed to simulate the coupled interaction between the flexible body and the fluid. Then, swimming performance will be measured during swimming in oscillating flow and vortices, in order to estimate the active and passive contributions to stability and energetics for fish swimming in complex flows. This work will use tiny inertial measurement units to measure the body orientation and acceleration of fishes as they swim, which will allow us to estimate measures of stability. These measurements will then be used in computational models, starting with the body properties of one of the fishes and varying it to examine the functional effects of changes in the neural control strategy, body mechanics, and body shape, and how they contribute to swimming performance. The use of computational models to explore the implications of comparative analyses will be a powerful new paradigm, allowing manipulation of individual variables that cannot be done experimentally. These techniques will help reveal how body shape and mechanics contribute to locomotor performance across the diversity in fishes and other animals.
