The world’s largest living organism is made up of millions of small creatures that reproduce and die off leaving a hard limestone skeleton. This is a colony that continually builds upon itself, creating massive reef structures over many generations. Coral reefs support over 25% of all known marine species. As one of the most complex ecosystems on the planet, coral reefs are home to over 4,000 different species of fish, approximately 700 known species of coral, and thousands of other marine animals.
Although coral is often mistaken for a rock or a plant, it is actually composed of tiny, fragile animals called coral polyps. When we say “coral,” we are actually referring to these animals and the skeletons they leave behind after they have died. The geological record indicates that the ancestors of modern coral reef ecosystems were formed at least 240 million years ago.
The largest coral reef on earth is Australia’s Great Barrier Reef stretching many thousands of kilometers down the east coast of the continent. The Great Barrier Reef is one of the most diverse ecosystems on our planet and an underwater paradise for avid divers.
The planet's second largest reef system is in the Meso-American Barrier Reef System, which extends from the tip of Mexico's Yucatán to Honduras.