Coral reefs support a quarter of all marine species

Despite covering less than 0.1 percent of the ocean floor, coral reefs are biodiversity hotspots, hosting an astonishing 25 percent of all known marine species. These vibrant underwater cities, often called the rainforests of the sea, are home to over a million species, from colorful fish and intricate corals to sponges and countless microorganisms. Scientists estimate that reefs alone support more than 4,000 fish species, many found nowhere else on Earth.