Biochemical mechanisms within the bodies of plants and animals program almost all their activities to specific phases of periodic events such as the time of day, the state of the tide, and the season of the year. Those organisms living within the intertidal zone--the area between high and low tides--face many environmental challenges that are eased tremendously by such chronobiological means. This monograph provides an authoritative, up-to-date account of research on the workings of intertidal animals' biological clocks. The book begins with a description of how tides are generated, and how the difficulties involved in studying organismic tide-associated rhythms may be overcome. The rest of the work focuses on rhythms and their properties, and the nature of the clocks that govern them. Comprehensive in scope, the book synthesizes over 350 research papers and contains over 129 figures. It is intended as a sequel to the author's well-known 1974 monograph Biological Clocks in Marine Organisms, incorporating the many advances in the field since the publication of the earlier volume. Aquatic ecologists, animal behaviorists, comparative physiologists, marine biologists, chronobiologists, and interested general readers will all want to read this important new work.