Corals and zooxanthellae have a symbiotic relationship, meaning that they benefit from each other in some way. Zooxanthellae are single-celled algae that live inside the tissues of many types of coral. In exchange for a place to live, the algae provide the coral with nutrients that they produce through photosynthesis.
The algae are able to photosynthesize because they have pigments that absorb light energy and convert it into chemical energy. This process also releases oxygen as a byproduct, which is used by the coral and other organisms living on the reef.
The coral, in turn, provides the algae with a protected environment and access to the nutrients and gases that they need to survive. The coral also benefits from the nutrients produced by the algae, which help it grow and maintain its hard, calcium carbonate skeleton.
The collaboration between corals and zooxanthellae is an important part of the functioning of coral reefs and the overall health of the marine ecosystem. Coral reefs are some of the most diverse and productive ecosystems on Earth, providing habitat for a wide variety of marine life and supporting the livelihoods of millions of people around the world through tourism, fishing, and other industries.