Speaker: Mike Tift, Associate Professor, Director of UNCW Marine Mammal Stranding Program, Department of Biology and Marine Biology, University of North Carolina Wilmington

Topic: Adult mammalian body mass spans more than eight orders of magnitude, from only a few grams to over 150,000 kg. Among the approximately 6,700 extant mammalian species, marine mammals comprise the group with the largest average body size, with the blue whale representing the largest animal known to have ever lived. Increasing body size is fundamentally associated with reductions in mass-specific metabolic and oxygen consumption rates, with important consequences for the physiological management of oxygen and reactive oxygen species (ROS). Marine mammals face an additional challenge of routine diving that requires prolonged breath holds that can range from seconds to several hours. During extended dives, some species routinely reduce blood oxygen concentrations to levels that would result in tissue injury or death in many other mammals. Yet, paradoxically, recent research has revealed that several deep-diving species maintain remarkably high concentrations of carbon monoxide (CO) in both blood and extravascular tissues, a finding that initially appears incompatible with efficient oxygen storage and utilization. In this seminar, I will explore how extreme body size shapes certain aspects of the physiology of large mammals, examine emerging mechanisms that allow diving mammals to tolerate severe and prolonged reductions in oxygen availability, and discuss new insights into the role of CO and the heme oxygenase/CO pathway in marine mammal physiology.