Coral reefs and their photosynthetic algae form one of the most ecologically and economically impactful symbioses in the animal kingdom. The stability of this nutritional mutualism and this ecosystem is, however, at risk due to increasing sea surface temperatures that cause corals to expel their symbionts. Symbioses with these microeukaryotes have independently evolved multiple times, and non‐coral cnidarians (e.g., sea anemon...

The feeding environment for planktotrophic larvae has a major impact on development and progression towards competency for metamorphosis. High phytoplankton environments that promote growth and development also correlate with a greater abundance of environmental microbes and incidence of pathogenic microbes, making these habitats potentially risky for larvae. Trade‐offs between metabolic processes for growth and immune functio...