Much of the current interest in the impact of the oceans on human health can be traced historically back to the earliest days of the fields of Experimental Marine Biology and Comparative Physiology. In Experimental Marine Biology, understanding of how anthropogenic pollutants impact aquatic organisms (aquatic toxicology) can be seen as a natural extension of early efforts to understand how variations in so-called “natural” environmental factors (e.g., oxygen, salinity) affected the physiology, reproductive capacity, and survivorship of marine organisms. Likewise, Comparative Physiology seeks to unify understanding of common physiological processes (e.g., osmoregulation, respiration) across many taxa; in this unification, it is not surprising that knowledge arises that is relevant to understanding human health. In this quest for unification, Comparative Physiology also gave birth to an experimental approach that has come to be known as the “August Krogh Principle,” which states: “For many problems, there is an animal on which it can be most conveniently studied.” While the above quote is attributed to the Danish physiologist August Krogh, it is clear that physiologists preceding Krogh applied the principle even earlier (Jørgensen, 2001). Regardless of its exact origin, we believe that the approach applies today both in the choice of sentinel species for tracking marine pollutants and understanding the mechanisms of their actions, and in the use of marine models for the efficient and insightful study of human diseases.