Reproduction of Marine Invertebrates, Volume I: Acoelomate and Pseudocoelomate Metazoans is a collection of papers that deals with the evolution of reproductive mechanisms and behavior in marine invertebrates. This collection starts with terminologies and basic events in marine invertebrate reproduction, including the method of estimating sexual reproductive activity, as well as the timing and patterns involved. The book notes that temperatures, salinities, or food availability should be favorable when the young are produced and when they are developing. One paper shows that the reproductive rhythm is dynamic and in some species is latitude-dependent. Other papers discuss the reproductive cycles of different marine invertebrates such as the Porifera, Cnidaria, Nemertinea, and Nematoda. These papers include topics on asexual reproduction, regeneration, sexual reproduction, and development, and then explain in detail the development of certain invertebrates from their kinorhynchs state (embryonic), to the molting stages, juvenile stages, then to adulthood. This book can be useful for marine biologists, marine ecologists, and students involved in marine biological and physical sciences.