Zoosanthellids

Zooxanthellae is a general term for single-celled dinoflagellate algae that live symbiotically within the tissues of many marine invertebrates, most famously in corals. These algae possess chlorophyll and other pigments, enabling them to perform photosynthesis. The host invertebrate provides the zooxanthellae with a protected environment and compounds necessary for photosynthesis, such as carbon dioxide and nitrogenous waste. In return, the zooxanthellae supply their host with a significant portion of their nutritional requirements through the products of photosynthesis, including sugars and oxygen. This symbiotic relationship is crucial for the survival and growth of many reef-building corals, as well as other organisms like anemones, jellyfish, and some bivalves. The vibrant colors often seen in corals are largely due to the pigments within the zooxanthellae. When corals are stressed, often by changes in water temperature or pollution, they can expel their zooxanthellae, leading to coral bleaching.