This volume offers contributions from leading experts in the biology of chaetognaths, or arrow worms--voracious carnivores which are exceptionally abundant in all the seas of the world. Until now there has been a lack of easily accessible information on this group, despite the fact that their vast numbers very likely render chaetognaths of major ecological significance in marine planktonic communities. This work is the first comprehensive survey. It deals with all aspects of chaetognath biology, including much recent and unpublished work. Two chapters are devoted to taxonomic relationships, two chapters cover morphology and anatomy, four chapters are concerned with physiology and behavior, three are devoted to ecology, and one chapter provides detailed information about the techniques necessary for studying the organism. The book will interest all marine biologists and zoologists working on plankton, along with invertebrate biologists, systematists, and advanced students of marine biology.