Coral Reefs Support 25% of All Marine Species

The incredible biodiversity of coral reefs stems from their unique architecture. These massive underwater structures are not rocks, but are built by colonies of tiny animals called coral polyps. Each polyp secretes a hard, calcium carbonate skeleton, and over millennia, these skeletons accumulate to form complex, three-dimensional mazes. This intricate framework provides an endless variety of niches—ledges, caves, and crevices—that serve as shelter, breeding grounds, and hunting territory for an enormous range of organisms. Much like a bustling city, the reef’s physical complexity allows countless species to find a home and coexist in a relatively small area.

The engine powering this vibrant ecosystem is a delicate symbiotic relationship. Living within the tissues of the coral polyps are microscopic algae called zooxanthellae. Through photosynthesis, these algae provide the coral with up to 90 percent of its energy, which fuels the skeleton-building process and gives the coral its brilliant color. This partnership is highly sensitive to environmental changes. When ocean temperatures rise, stressed corals expel their algal partners. This event, known as coral bleaching, turns the coral stark white and leaves it starving. Without its primary energy source, the coral cannot survive for long, threatening the collapse of the entire reef community that depends on it.