For over a half-century, Dr. George Somero has trekked to various corners of the planet chasing down marine species that are adapted to extremes of temperature. His Ph.D. work at Stanford focused on the ocean’s coldest fish—Antarctic species whose body temperatures hover near the freezing point of seawater (-2°C or 29°F). Somero's current research in China examines the world’s hottest animals: tiny intertidal snails that thrive with body temperatures near 55°C (130°F). Even though all aspects of physiology, for example, cardiac function and metabolic activity, are highly sensitive to temperature, all animals manage to conduct basically the same physiological tasks, thanks to pervasive adaptations to temperature at the biochemical level. This talk will examine these adaptations in the context of our rapidly changing world, and will address the following questions: How does evolution ‘tweak’ the properties of key physiological and biochemical systems to modify their thermal optima and tolerance limits, thereby allowing animals to thrive across an approximately 60°C range of body temperatures? What factors will determine how successfully different marine animals can keep up with the challenges posed by climate change—who will be “winners” and who will be “losers” in our warming world?