This book presents a comprehensive analysis of vertebrate blood proteins. The analysis of fish proteins require special attention because of their supreme structural diversity. The chapters focus on the conceptions of blood proteins organization and theoretical models of blood proteins transcapillary exchange in mammals, as well as an analysis of the blood proteins structural-functional diversity in cartilaginous Chondrichthyes and bony Osteichthyes fishes, inhabiting the seas, fresh and brackish waters.