Updated by: Arabinda Naik
Corals and zooxanthellae exist in a mutualistic relationship: corals cannot live or are handicapped without them. This restricts coral distribution to areas where zooxanthellae can thrive. Corals die after 18 days in total darkness, but they are completely carnivorous and expel zooxanthellae when starved. Zooxanthellae probably seek corals to satisfy their own nitrate and phosphorus requirements and in return help in the skeleton formation of coral. They help to dispose of H2C () released as by-product of the formation of CaC03.
The mutualistic relationship between coral polyps and zooxanthellae plays a critical role in the formation and growth of coral reefs. Zooxanthellae are photosynthetic algae that live within the tissues of coral polyps. They provide the coral polyps with essential nutrients, primarily in the form of glucose, which the coral polyps use for growth, energy, and reproduction. In return, the coral polyps provide the zooxanthellae with a sheltered environment and carbon dioxide, a byproduct of the coral polyps' respiration. This mutually beneficial relationship is essential for the survival and growth of both organisms.
The zooxanthellae's photosynthetic activity contributes significantly to the coral polyps' energy budget. It is estimated that zooxanthellae provide up to 90% of the energy requirements of coral polyps. This energy is essential for the coral polyps to grow, build their calcium carbonate skeletons, and reproduce. Without the zooxanthellae, coral polyps would not have enough energy to thrive and form coral reefs.
The zooxanthellae also play a role in the coral polyps' calcium carbonate deposition. Coral polyps secrete calcium carbonate to build their skeletons, which form the foundation of coral reefs. The zooxanthellae's photosynthetic activity helps to remove carbon dioxide from the surrounding water, which increases the availability of carbonate ions, the building blocks of calcium carbonate. This increased availability of carbonate ions facilitates the coral polyps' calcium carbonate deposition, contributing to the growth and development of coral reefs.
In addition to their direct contributions to coral polyp growth and calcium carbonate deposition, zooxanthellae also play a role in maintaining the health and resilience of coral reefs. They help to regulate the coral polyps' internal environment, including their pH and oxygen levels. Zooxanthellae also produce compounds that protect coral polyps from environmental stressors, such as ultraviolet radiation and temperature fluctuations.
The mutualistic relationship between coral polyps and zooxanthellae is essential for the formation, growth, and survival of coral reefs. These ecosystems provide vital habitats for a vast array of marine life and play a crucial role in protecting coastlines from erosion and storms. Understanding and preserving this symbiotic relationship is critical for the conservation of coral reefs and the marine ecosystems they support.