The field of study which deals with the different complexities of the endocrine systems of vertebrate and invertebrate systems is termed as comparative endocrinology. It conducts analysis at the sub-molecular, cellular, molecular and organismal level. Comparative endocrinology mainly focuses on the morphological and functional aspects. The field of science which studies the nervous system is termed as neurobiology. It combines concepts from a variety of disciplines such as anatomy, physiology, molecular biology, cytology and developmental biology. The major areas of study within this discipline are the emergent and basic properties of neural circuits and neurons. Some of its prominent branches are affective neuroscience, cellular neuroscience, cultural neuroscience and molecular neuroscience. This book unravels the recent studies in the field of comparative endocrinology and neurobiology. It traces the progress of this field and highlights some of its key concepts and applications. Those in search of information to further their knowledge will be greatly assisted by this book.