Conceptual Breakthroughs in Comparative Animal Physiology tells a story of innate human curiosity about the natural world, and a deeply creative discipline, shaped by varied environments, unusual organisms, elegant experiments, and the persistent effort to understand how animals work and why they work the way they do—along the way discovering “adaptations and mechanisms of the most surprising character”. Written by two leading experts in the field, each chapter reflects on the origins of ideas and the approach of turning natural diversity into experimental design. From deserts to oceans, from the anoxia-tolerant animals to endothermic insects, from deep-diving mammals to the integration of “omics,” each chapter follows the discoveries and people who were compelled to modify their view of “what life can do.” The chapters also highlight the long-term influence of key conceptual breakthroughs, demonstrating how insights from comparative physiology have shaped not only the field itself but also, ecology, evolution, and engineering. As scientists strive to understand the complexity of living systems, the book underscores the inherent integrative nature of comparative physiology, revealing a process that strives to connect genes to organisms and organisms to environments, and providing a framework for understanding the diversity of life. This is an essential resource for undergraduates, graduate students and researchers interested in physiology with its comprehensive synopsis on the field’s foundational history and significant advances.