Water is fundamental to life and all metabolic reactions are influenced by the aqueous environment in which they occur. Osmoregulation and water balance are therefore absolutely essential topics in animal physiology. Animal Osmoregulation collates a widely dispersed literature to produce a comprehensive and authoritative synthesis of the field, providing detailed examples of osmoregulatory processes at the organismal, organ and cellular level. It incorporates clear background information on ion regulation and transport (specifically in the light of recent molecular studies) and illustrates the physical principles to which each organism must adhere, as well as the phylogenetic constraints within which it must operate. As with other titles in the Oxford Animal Biology Series, the topic is addressed using examples from throughout the animal kingdom, identifying common themes that transcend taxonomy.