Ecologists have long struggled to predict features of ecological systems, such as the numbers and diversity of organisms. The wide range of body sizes in ecological communities, from tiny microbes to large animals and plants, is emerging as the key to prediction. Based on the relationship between body size and features such as biological rates, the physics of water and the amount of habitat available, we may be able to understand patterns of abundance and diversity, biogeography, interactions in food webs and the impact of fishing, adding up to a potential 'periodic table' for ecology. Remarkable progress on the unravelling, describing and modelling of aquatic food webs, revealing the fundamental role of body size, makes a book emphasising marine and freshwater ecosystems particularly apt. Here, the importance of body size is examined at a range of scales that will be of interest to professional ecologists, from students to senior researchers.

Alan Hildrew is Professor in the School of Biological and Chemical Sciences at Queen Mary, University of London.

Dave Raffaelli is Professor at the University of York.

Ronni Edmonds-Brown is a senior lecturer in Environmental Sciences at the University of Hertfordshire.