Communication in Marine Mammals

Communication is a process by which a sender produces a signal, which alters the probability of a subsequent behav­ ior in a receiver(s). Often, but not always, communication facilitates social behavior. Given the highly social behavior found in many marine mammals, the study of communicative behavior is essential to understanding the role that signaling plays in regulating social interactions for these species. To understand communication in a given species, it is important to view the mode of the signal (i.e., visual, acoustic, tactile, gustatory, or olfactory), medium in which the signal is transmitted (air and/or water), mechanisms of signal produc­ tion (anatomical and/or physiological), function(s) of the signal (e.g., aggression/submission, mate attraction, parental care, territorial defense), and whether signals are multi-modal. This chapter is a brief overview of communication in marine mammals. Even with more than 40 years of focused studies on the social lives of marine mammals, relatively little is understood about the majority of species within marine mammal groups—cetaceans, pinnipeds, sirenians, sea otters (Enhydra lutris), and the polar bears (Ursus maritimus). Behavioral characteristics and social relationships are adapted to each species ’ unique ecology. Marine mammals are either amphibious or totally aquatic. Each life mode imposes differ­ ent constraints on signaling and communication. A paucity of stud­ ies on communication exists for many marine mammals, especially polar bears, sea otters, dugongs (Dugong dugon), and manatees (Trichechus spp.). Even less is known about the marine otter (Lontra felina), so we do not discuss this species. The majority of research on communication has been conducted on pinnipeds (such as Weddell seals, Leptonychotes weddellii; and California sea lions, Zalophus cal­ ifornianus) and cetaceans (particularly bottlenose dolphins, Tursiops spp.; killer whales, Orcinus orca; and humpback whales, Megaptera novaeangliae). Thus, our discussion highlights and compares species predominantly represented in the literature.