The physics of animal locomotion

In this chapter the physics behind animal movement, the adaptations found in locomotion to generate forces, and the mechanisms reducing the cost of transport are discussed. The ability to minimize costs and maximize movement speed is part of the biomechanical physics of animal locomotion. For any type of active movement (e.g. walking, running, swimming, or flying), the animal is required to produce forces to overcome resistance and in many cases also gravity. For terrestrial locomotion, this is achieved by generating ground reaction forces, while in air and water by generating fluid dynamic forces. Due to scaling laws in physics, the speed that can be achieved and the cost of transport are correlated with the size of the animal. Moving across scales thus has consequences for our expectations regarding animal movement, including the occurrence of seasonal migrations, which may be limited by the speed and cost of locomotion.