Chapter 17 - Sound production and propagation in cetaceans

Abstract

Marine mammals in the cetacean order are the whales, dolphins, and porpoises and are separated into two groups or suborders: toothed whales (Odontocetes) and baleen whales (Mysticetes). They have complex acoustic repertoires comprising several major types of vocalizations for communication, navigation, foraging for prey, group cohesion, and avoiding predators. They rely heavily on sound for all major life functions as acoustic energy propagates in water more efficiently than almost any other form of energy. Toothed whales generate sound from the phonic lips by letting air flow across them to excite vibration. The sound propagates through the various structures in the forehead and is finally projected into the water. All toothed whales produce clicks for echolocation, while most of them can also emit tonal whistles for intraspecific communication. Baleen whales generate complex, repetitive, geographically distinct songs and calls that are associated with breeding and feeding behaviors. This chapter focuses mainly on toothed whale since far more is known about their sound production, propagation, reception, and biological function relevant to the theme of this book; however, a section on baleen whales is included.