Never so pleased, sir. 'Twas an excellent dance, And for a preface, I never heard a better. Two Noble Kinsmen, Act III, Sc.S This volume is based mostly on the lectures delivered at an Advanced Study Institute (ASI) of the same title held in July 1977. One lecture given is not in the volume and three chapters, although not based on lectures delivered, have been added to better balance the book. A chapter on the ecosensory functions in crustaceans could not be put in due to time contingency. This absence is deeply regretted. The idea to hold an ASI on Sensory Ecology evolved slowly, main­ ly due to my own research interest in the past and partly to the discussions I had with a number of colleagues, particularly Dr. John Lythgoe of the University of Sussex. The purpose was to interface Sensory Physiology with Ecology so that workers in those fields will develop a greater awareness for each other. Sense organs have of course evolved to keep their possessors.~ware of the environment and changes in it. Thus, normally one could expect that a study of their functions will be undertaken in relation to environmental parameters.