Symbiosis refers to the biological interaction between two organisms or species, living in close association. In this book, the authors present current research in the study of the evolution, biology and ecological effects of symbiosis. Topics discussed include the evolution of arbuscular mycorrhiza; legume properties and symbiosis; sea anemones and hermit crab symbiosis in temperate seas; the agronomic and ecological importance between legumes and rhizobia; the behavioural, physiological and ecological effects of organisms in symbiotic associations; and a neuronal model with symbiotic interactions.