The document summarizes a study that experimentally demonstrates caspase-induced apoptosis plays a key role in coral bleaching and death from thermal stress. The study shows increased temperature leads to higher reactive oxygen species production by symbiotic algae, which triggers caspase activity in the coral host and apoptosis. Inhibiting caspase activity prevented bleaching and apoptosis. The study develops a model relating coral mortality and bleaching to algal symbiont thermal sensitivity and host caspase cascade activation. It concludes selection may favor corals with less thermally sensitive symbionts or hosts unable to activate apoptosis in response to stress.