INTRODUCTION

Orientation is crucial for almost all organisms, from bacteria to mammals, for selecting habitat or feeding grounds, deciding up from down, or just keeping track of your position, or your neighbour's. The marine environment is an especially rich source of material, particularly for the study of migration, where many animals cover enormous distances, and appear do this with reference to very few sensory cues. The mechanisms underlying these processes, and the benefits they bring to the organism, are only now beginning to be understood.