This book is actually a product of efforts of many people, not only of the authors. W ide investigations of marine mammals began in Russia (that time, in the former Soviet Union) in the 1960s when a few teams of enthusiasts founded in captivity experimental stations intended for keeping dolphins and seals and for performing experimental studies of these fascinating animals. It was a time when attention of many people throughout the world was attracted to dolphins and other marine mammals due to appearance of oceanariums and dolphinariums, which demonstrated unique capabilities of these animals. So scientists in many countries concentrated on studies of them. There was much to learn about the morphology, physiology, and psychology of marine mammals, and investigators spending their time and efforts on studies in this field were rewarded by a number of surprising findings. The authors of this book represent one of such research teams focused on the neuro- and sensory physiology of marine mammals. A few decades of studies naturally resulted in the idea to summarize in a book both the results of these studies and a large body of data in adjacent fields. Our goal was to synthesize the many research findings and the present knowledge on sensory capabilities and mechanisms of sensory systems of aquatic mammals. We realize, however, that the appearance of this book was made possible due to the help and assistance of many colleagues.

This volume constitutes a series of invited chapters based on presentations given at an International Conference on the Sensory Biology of Aquatic Animals held June 24-28, 1985 at the Mote Marine Laboratory in Sarasota, Florida. The immediate purpose of the conference was to spark an exchange of ideas, concepts, and techniques among investigators concerned with the different sensory modalities employed by a wide variety of animal species in extracting information from the aquatic environment. By necessity, most investigators of sensory biology are specialists in one sensory system: different stimulus modalities require different methods of stimulus control and, generally, different animal models. Yet, it is clear that all sensory systems have principles in common, such as stimulus filtering by peripheral structures, tuning of receptor cells, signal-to-noise ratios, adaption and disadaptation, and effective dynamic range. Other features, such as hormonal and efferent neural control, circadian reorganization, and receptor recycling are known in some and not in other senses. The conference afforded an increased awareness of new discoveries in other sensory systems that has effectively inspired a fresh look by the various participants at their own area of specialization to see whether or not similar principles apply. This inspiration was found not only in theoretical issues, but equally in techniques and methods of approach. The myopy of sensory specialization was broken in one unexpected way by showing limitations of individual sense organs and their integration within each organism. For instance, studying vision, one generally chooses a visual animal as a model.

From crocodiles and penguins to seals and whales, this comprehensive and authoritative synthesis explores the function and evolution of sensory systems in animals whose ancestors lived on land. Together, the contributors explore the dramatic transformation of smell, taste, sight, hearing, balance, mechanoreception, magnetoreception, and electroreception that occurred as lineages of amphibians, reptiles, birds, and mammals returned to aquatic environments. Each chapter integrates data from fields including sensory physiology, anatomy, paleontology, and neurobiology. A one-stop source for information on the sense organs of secondarily aquatic tetrapods, Sensory Evolution on the Threshold sheds new light on both the evolution of aquatic vertebrates and the sensory biology of their astonishing transition.

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 comprehensive book provides new insights into the morphological, metabolic, thermoregulatory, locomotory, diving, sensory, feeding, and sleep adaptations of Cetacea (whales and dolphins), Pinnipedia (seals, sea lions and walrus), Sirenia (manatees and dugongs) and sea otters for an aquatic life. Each chapter reviews the discoveries from previous studies and integrates recent research using new techniques and technology. Readers will gain an understanding of the remarkable adaptations that enable marine mammals to spend all or most of their lives at sea, often while hunting prey at depth.

Advances in Physiological Sciences, Volume 31: Sensory Physiology of Aquatic Lower Vertebrates covers the proceedings of the symposia of the 28th International Congress of Physiology. The book presents 17 papers that detail advance findings in the sensory physiology of aquatic lower vertebrates. The coverage of the text includes electroreceptors in Indian catfish teleosts; electroreceptive microampulla in the African mudfish Clarias lazera; and species specificity of electric organ discharges in a sympatric group of gymnotoid fish from Manaus. The book also presents comparative studies, such as the sex differences in the electric organ discharge of Eigenmannia virescens and the effect of gonadal maturation; and behavioral studies, such as social behavior in mormyrid fish. The book will be of great interest to marine biologists, ethologists, and zoologists.