Coral reefs and tropical habitats are threatened worldwide by global warming and pollution stress. The purpose of these studies was to evaluate potential strategies for using jellyfish for toxicological assessments and as potential toxicological models for corals and other Cnidarians. Laboratory studies were conducted with jellyfish and three species of corals that were exposed to copper; and studies with corals exposed to pyrene and elevated temperatures were conducted. Observational (pulsation rate in jellyfish and bleaching in corals) as well as cellular biomarker responses (glutathione (GSH), lysosomal destabilization, and tissue Cu in jellyfish; GSH in corals) were assessed. Jellyfish pulsation rate, lysosomal destabilization, and tissue Cu levels were significantly correlated. Likewise, GSH levels were significantly correlated with tissue Cu, lysosomal destabilization and pulsation rates. Jellyfish tended to be more sensitive than corals to Cu exposures. Studies were conducted with adults and larvae of brain corals and other species from Curaçao to determine the baseline glutathione levels. Glutathione levels of these Cnidarians were much lower than those of more traditional bioindicators such as mussels or oysters. Glutathione levels of adult jellyfish were lower than adult coral levels. The GSH levels of early life history stages of corals (especially larvae) were lower than adult levels, potentially indicating that these stages could be more sensitive than adults. The GSH levels of the younger coral stages were similar to the GSH levels of jellyfish adults. Species-specific differences in the sensitivity of corals to the different pollutants were observed. This work was facilitated by partnerships with Discovery Place Science (a public science exploration center), CARMABI (Caribbean Research and Management of Biodiversity), and SECORE International which are actively engaged in the culture of Cnidarians and marine educational programs.