Swimming Strategies for Energy Economy

The laws of physics are rigid and fixed. Animals, therefore, are restricted in their use of available energy in accordance to the constraints of mechanics and thermodynamics. Evolutionary success dictates that a large proportion of the available energy reserves be allocated to reproductive effort despite the demand by other energy consuming functions. Therefore, mechanisms that reduce energy costs for non-reproductive functions relative to total energy reserves have an adaptive benefit for individuals (Fausch, 1984). As the laws of physics are inflexible and the available energy limited, animals have found ways to exploit these laws for their own benefit. Locomotion is an energy demanding activity. Swimming by fishes permits them to seek out new energy resources, but comes at a cost to transport the body mass over a distance. For movement in water, the kinetic energy is transferred from the movement of the body to the fluid medium, both to replace momentum losses associated with viscosity and induced energy losses associated with this replacement. This energy loss from the animal is due to the high density and viscosity of the water in conjunction with the shape and texture of the body surface, and the animal’s propulsive movements (Webb, 4