Climate change is threatening important marine ecosystems such as coral reefs. Increasing ocean temperatures put corals under periods of extreme heat stress, which causes bleaching. Bleaching-susceptible corals expel their symbiotic algae, putting them at risk for starvation and death. To understand the mechanistic processes of this break-down of symbiosis, we studied the model system Exaiptasia diaphana after a sub-lethal, 2-week heat stress. Using important physiological parameters of health such as pHi and respiration, we have preliminarily found an important influence of temperature stress rather than bleaching. While there are other physiology assays yet to be analyzed, these results can help direct the field towards other ways of understanding coral symbiosis more fully on a mechanistic level in order to preserve tropical species.