This monograph provides a comprehensive guide to plankton ciliates. The authors collected and critically reviewed the widely distributed literature on plankton ciliates and supplemented these data with a vast amount of original investigations. This book is intended for use by people without specific knowledge about ciliates, but is also useful for researchers and people with an environmental background. It will also be helpful in training courses on basic and applied limnology, as well as in biodiversity research and conversation.