ABSTRACT
One major factor inuencing the morphological design of marine mammals is how much time they spend in water, and what they do while in it. Some animals have evolved a body shape and propulsion system that not only minimizes drag, but also optimizes thrust generation (i.e., whales and dolphins). Not surprisingly, these animals happen to travel over very large distances in the water or chase very fast prey. Other animals have not optimized their hydrodynamics but rather other anatomical characteristics that are more important for other critical life functions, many of which occur on land, at the expense of increased locomotor costs in water. In effect, many marine mammals are faced with conicting physiological demands of an amphibious lifestyle (i.e., pinnipeds), while others have evolved fully aquatic niches (i.e., cetaceans). In this chapter, we explore the mechanisms that marine mammals use to achieve different levels of swimming performance. Moreover, we will review specic anatomical and behavioral adaptations in a comparative context to understand the evolution of locomotor traits that characterize this extraordinary guild of oceanic predators.
