This book evolved through the efforts of several organizations and the dedication of many individuals. In 1987, we received arequest to propose a workshop topic for the Fifth International Theriological Congress (ITC) to be held in August 1989 in Rome, Italy. After looking up the meaning of the word "theriological" in the dictionary and discovering that it pertains to mammalian behavior, we decided a symposium on sensory abilities of whales and dOlphins would be an interesting topic. The ITC convenes only every five years and has the distinction of being very weIl attended by scientists from around the world. We thought that hosting a workshop in conjunction with the ITC would attract a variety of international scientists that rarely have the opportunity to interact. Fortunately for all involved, our prediction was correct. The first two days of the workshop, 23-24 August 1989, were held in conjunction with ITC and the nearly 1,000 attending scientists were able to view our posters and listen to lectures. The third day was limited to only ab out 65 invited scientists who were divided into topical working groups chaired by a rapporteur.

This book is a collection of original research papers given at a symposium entitled "Sensory Systems and Behavior of Aquatic Mammals", hosted by the USSR Academy of Sciences. The meeting was held in Moscow from 16 to 25 October, 1991 and involved nearly 100 scientists from around the world. The major headings of the book correspond to the session topics at the symposium. This meeting was not the first dedicated to problems of sensory systems in aquatic mammals. Experts in this field met several times previously to discuss important problems of sensory functions in echolocating animals. symposia on biosonar systems were held in Frascati, Italy in 1966, then in Jersey, France in 1978, and in Helsingor, Denmark in 1986. Papers presented at these meetings were pUblished in books that advanced significantly the understanding of sensory systems (Busnel and Fish, 1980; Nachtigall and Moore, 1988). Initially, echolocating bats were the main subjects of consideration. However, studies on echolocating aquatic mammals, whales and dolphins, increased from one meeting to the next. Indeed, aquatic mammals are of exceptional interest for studying the adaptation of sensory functions for echolocation in specific aquatic environments. As a natural consequence of these developments, the 1989 symposium in Rome was devoted specifically to the sensory systems of cetaceans (Thomas and Kastelein, 1990). This symposium was held within the Fifth International Theriological Congress and was attended by many scientists.

This book evolved through the efforts of several organizations and the dedication of many individuals. In 1987, we received arequest to propose a workshop topic for the Fifth International Theriological Congress (ITC) to be held in August 1989 in Rome, Italy. After looking up the meaning of the word "theriological" in the dictionary and discovering that it pertains to mammalian behavior, we decided a symposium on sensory abilities of whales and dOlphins would be an interesting topic. The ITC convenes only every five years and has the distinction of being very weIl attended by scientists from around the world. We thought that hosting a workshop in conjunction with the ITC would attract a variety of international scientists that rarely have the opportunity to interact. Fortunately for all involved, our prediction was correct. The first two days of the workshop, 23-24 August 1989, were held in conjunction with ITC and the nearly 1,000 attending scientists were able to view our posters and listen to lectures. The third day was limited to only ab out 65 invited scientists who were divided into topical working groups chaired by a rapporteur.