Coral Reef

“A coral reef is not a backdrop. It is a living community of billions of organisms — and one of the most complex ecosystems on earth.”

What Is a Coral Reef? – Understanding the Foundation of the Great Barrier Reef

Coral reefs are among the most biodiverse ecosystems on the planet. Built over thousands of years through the accumulated calcium carbonate skeletons of coral polyps, they provide habitat for an estimated 25% of all marine species — despite covering less than 1% of the ocean floor.

The Great Barrier Reef is the world’s largest coral reef system, stretching over 2,300 kilometres along the Queensland coastline and comprising more than 2,900 individual reef structures. It is one of the Seven Natural Wonders of the World and a UNESCO World Heritage Area.

How Coral Reefs Are Formed

Coral reefs begin with coral polyps — tiny, soft-bodied animals related to sea anemones and jellyfish. Each polyp secretes a hard limestone cup (the corallite) as its external skeleton. Over centuries and millennia, these accumulated skeletons create the physical structure of the reef.

Most reef-building corals live in a symbiotic relationship with microscopic algae called zooxanthellae, which live within the coral’s tissue and provide up to 90% of its energy requirements through photosynthesis. This is why coral reefs are found in shallow, well-lit tropical and subtropical waters — the zooxanthellae need sunlight.

Types of Coral Reefs

The Great Barrier Reef contains several distinct reef types. Fringing reefs grow close to the shore and are attached to land masses. Barrier reefs run parallel to the coast and are separated from it by a lagoon — the classic form of the Great Barrier Reef. Coral atoll reefs form around volcanic islands as the land subsides over time, eventually leaving a ring of reef around a central lagoon. Platform or patch reefs form as isolated structures in open water.

Half Day Reef ToursShorter reef trips from Cairns and Port Douglas when you are short on time.View tours →Whitsunday Reef ToursSnorkel and dive trips from Airlie Beach and Hamilton Island.View tours →Cairns Reef ToursSnorkel, dive and day trips to the reef from Cairns.View tours →Port Douglas Reef ToursSnorkel, dive and day trips to the reef from Port Douglas.View tours →

Why Coral Reefs Matter

Coral reefs provide ecosystem services worth trillions of dollars globally — supporting fisheries that feed hundreds of millions of people, protecting coastlines from wave erosion, driving tourism economies, and containing compounds that have contributed to medical treatments.

The Great Barrier Reef alone contributes approximately $6.4 billion to the Australian economy annually and supports tens of thousands of jobs.

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