Ascidians are the invertebrate group that gave rise to vertebrates, thus the biology of ascidians provides an essential key to understanding both invertebrates and vertebrates. This book is the first to cover all areas of ascidian biology, including development, evolution, biologically active substances, heavy metal accumulation, asexual reproduction, host-defense mechanisms, allorecognition mechanisms, comparative immunology, neuroscience, taxonomy, ecology, genome science, and food science. The 69 articles that make up the collection were contributed by leading ascidiologists from all over the world who participated in the First International Symposium on the Biology of Ascidians, held in June 2000 in Sapporo, Japan. For scientists and students alike, the book is an invaluable source of information from the latest, most comprehensive studies of ascidian biology.