Chapter 26: Oxygen, Carbon Dioxide, and Internal Transport: Diving by Marine Mammals

The authors emphasize the mechanical principles of force, torque, and leverage, introducing key concepts like work, power, and efficiency as they relate to muscular output and movement. The structure and function of skeletal muscles are reviewed in the context of movement, with particular focus on the arrangement of muscle fibers, sarcomere contraction, and force-velocity relationships. Fast-twitch and slow-twitch muscle types are compared, showing how animals fine-tune muscle composition to optimize for speed, endurance, or force. Tendons and elastic elements are also discussed as energy-saving adaptations, particularly in hopping animals like kangaroos that store and reuse kinetic energy with each stride. The authors detail how limb morphology, body size, and gait transitions influence locomotor performance. For example, larger animals use longer stride lengths and tend to shift to more energy-efficient gaits as speed increases. In aquatic locomotion, the chapter explains how animals overcome drag using streamlined bodies and axial propulsion, as seen in fish and marine mammals. Terrestrial animals manage gravity and ground reaction forces through joint mechanics and synchronized limb movements. The aerodynamics of flight are discussed through the physics of lift generation, wing loading, and flapping vs. gliding flight styles in birds, bats, and insects. The chapter also introduces quantitative techniques to study locomotion, including force platforms, kinematic analysis, and respirometry to measure cost of transport. Comparative examples show how different animals maximize efficiency—whether it's a snake’s lateral undulation, a cheetah’s sprint, or a hummingbird’s hovering. The role of neural control is also discussed, particularly central pattern generators (CPGs) that coordinate rhythmic limb movements without constant brain input. Ultimately, this chapter synthesizes biomechanics, physiology, and behavior to show how movement is a product of anatomical design and evolutionary pressure. Whether escaping predators, migrating long distances, or foraging efficiently, animal locomotion reflects a fine-tuned integration of mechanical and metabolic systems.