The biology of cetaceans is one of the most compelling areas of research because of the extreme adaptations whales and dolphins have had to undergo in order to manage a life in the water. The fossil record of cetaceans is rich, and though much attention has been given to the origins of whales from terrestrial artiodactyls, it is important to realise that the biology, physiology, and behaviour of modern cetaceans has not remained unchanged since this initial transition to being aquatic. This books discusses and presents new data on the behaviour and biology of whales and dolphins including: the cenozoic environmental changes and evolution of baleen whales, the ecological and evolutionary divergence in whales and dolphins, the parasite fauna of cetaceans, and others.