Biomechanics of fin/body intereactions in fish propelled by median and/or paired fins

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How do animals work? In whole animals the question usually refers to the relationship(s) of structure to function. For example, how does a fish swim? The mechanics (how a fish interacts with water to produce propulsive forces), energetics (how much energy it costs a fish to swim) and efficiency (how much energy is wasted) are well understood for fish that swim by sending waves down their bodies. This has allowed for an understanding of the feats of endurance of migrating salmon, the high swimming speed of tuna and the rapid acceleration of pike as they catch their prey. Less is known about fish that have a protective rigid body (like boxfish and puffer fish) that swim by fin movements which may act like paddles rowing, wings or undulating sheets. In previous studies, I identified a number of adaptations that allow these fish to move efficiently through the complex, cluttered environments such as coral reefs or kelp beds in which they live. This study looks at a number of energetically advantageous mechanical interactions between the fish's fins and body. For example, a waving sheet-like fin attached to a rigid body is very effective and efficient due to a positive mechanical interaction with the body to which it is attached. The increased pressure on the underside of a paddling fin as it comes up close to the side of the body of an angel fish is probably sufficient to stop the fin without the need for any muscle power. Wing-like fins that flap rapidly against the sides of a swimming fish can produce jet effects as water is squeezed out between the underside of the fin and the side of the body. Recently, engineers have turned to biology for ideas and models for structures and vehicles that they build. This is the new science of biomimetics. Fin propelled rigid bodied fish are viewed as biomimetic model systems for the design and function of automated underwater vehicles to be used in environmental monitoring such as detecting concentrations and sources of pollutants.