Zooplankton is a major work of reference for researchers in plankton biology, physiology and behavior, which combines behavioral and psychological approaches to the study of plankton on present and interdisciplinary investigation of sensory processes in pelagic environments. The breadth of perspective thus achieved provides valuable insights into the larger scale ecological processes of biological productivity, community structure and population dynamics. Technological advances in almost all aspects of biological research have opened up opportunities for a re-examination of the sensory ecology of planktonic organisms. In this wide-ranging collection, leading researchers in planktonic behavior and physiology address the rapidly developing interface between these two major areas. The studies presented range from the laboratory to the field and from the cell to the whole organism, but share the common goal of understanding the special sensory world of organisms that live in pelagic environments and how their behavior and physiology relate to it.