Symbiotic partnerships between unrelated organisms are prevalent in all environments and are a driving force in evolution. Many cnidarians, including corals and anemones, engage in a symbiosis with photosynthetic single-celled algae that live within their tissues. These partnerships are of global significance as corals form both the trophic and structural foundation of coral reef ecosystems. The partners in coral-algae symbioses have a series of complex cellular and molecular conversations that regulate and maintain this intimate association. In this project, the investigators will examine the role of host coral and anemone immune systems in recognizing and regulating their symbiotic algal partners. Animal immunity is comprised of many different genes and cellular pathways that are set up to detect and regulate both detrimental and beneficial invaders. This project will identify specific immunity genes, proteins and pathways in corals and anemones and experimentally test their role in the symbiotic partnership. These studies will include examinations of the collapse of the partnership that occurs when corals are stressed by elevated temperatures associated with climate change, a phenomenon termed coral bleaching. During bleaching, the symbiotic algae exit the host, leaving the host undernourished and susceptible to disease. Bleaching is threatening the health of reefs worldwide. Insight into the basic biology of corals is critical to gain a full understanding of whether or not corals have the capacity to adapt to and survive climate change. This project will contribute to the education and training of graduate students, undergraduates and high school students. Students will be executing the majority of the work and in doing so they will gain training in fieldwork on a coral reef and laboratory work using state-of-the-art cell and molecular biology techniques. This training will prepare these young scholars for futures in science, technology and education.