Offering extensive information on tardigrades, this volume begins with a chapter on the history of tardigrades, from the first description by Goeze in 1773, until 1929, when the most comprehensive monographic approach by E. Marcus was published. Tardigrades’ organ systems, including their integument, body cavity, digestive, muscular, nervous and reproductive systems, as well as their overall external morphology, are summarized in the second chapter. Subsequent chapters present the current state of knowledge on tardigrade phylogeny, biogeography, paleontology, cytology and cytogenetics. In addition, the book provides insights into the ecology of tardigrades in marine, freshwater and terrestrial habitats. The reproduction, development and life cycles are summarized and the extraordinary environmental adaptations of encystment and cyclomorphosis, desiccation tolerance, freezing tolerance and radiation tolerance are discussed in detail. Further chapters provide an overview of key approaches in molecular tardigrade studies and describe techniques for sampling and sample processing. The book closes with a list of tardigrade taxa up to a sub-generic level, including the type species of each genus, the numbers of lower taxa in each taxon, and the main environments in which the taxa were found. Given its depth of coverage, the volume offers an invaluable resource for scientists from various disciplines who plan to research tardigrades, and for all others who are interested in these fascinating animals.