Dinoflagellates are important primary producers, symbionts and, at the same time, heterotrophic consumers and parasites. The species composi- tion in benthic habitats is quite distinct from planktonic habitats. Our un- derstanding of benthic dinoflagellate biodiversity, biogeography, toxicology and ecology has improved but is still rudimentary. Benthic harmful algal blooms have attracted increasing interest because of the impact of ciguatera poisoning, the most important food-borne disease of non-bacterial origin worldwide, which is caused by benthic dinoflagellate species. Ciguatera poisoning appears to have increased worldwide in recent years. This publication is an updated summary of the taxonomy of currently described taxa and includes morphological and molecular genetic information for species identification. It contains the most comprehensive review of benthic dinoflagellate toxins published so far. The book also describes methods of study, discusses phylogenetics and evolution, and highlights their scientific relevance as well as the health and economic impacts of benthic dinoflagellates for society. This book is a fundamental contribution to improving the monitoring of benthic dinoflagellates worldwide: 242 species in 63 genera are presented, illustrated with more than 240 color images, about 250 electron micrographs and more than 330 drawings.