This book presents all Malacostracan cructaceans occurring in the Baltic Sea in water salinity from 2 to 15 psu. The Baltic sea is very special due to its low salinity and characteristic fauna. For each of the 58 species the systematic position, the origin and distribution in European waters are given, and the environmental preferences, the role in the food web and human economy described. The book describes the history of the Baltic sea and the occurrence of crustaceans in its history against the terms of hydrological conditions, explaining why in the Baltic sea only part of all marine crustaceans occur. The book is richly illustrated with photographs and beautiful pictures of animals specifically prepared for this book.