If you’ve seen the movie “Finding Nemo,” then you’ve had a tiny glimpse of one of the most fascinating ecosystems on our planet. As Marlin, a clown fish, sets out in search of his son Nemo, he encounters all sorts of other creatures that live in and around his home, the Great Barrier Reef.

Image © Radius Images/Jupiter Images Clark's Anemonefish, Great Barrier Reef, Australia

Quick Facts Approximately 2 million tourists visit the Great Barrier Reef each year.

Situated in the Coral Sea, just off the coast of Queensland, Australia, and stretching for more than 1,400 miles, the Great Barrier Reef is the world’s largest coral reef system. It is a complex, biologically diverse ecosystem that serves many important roles such as providing food and shelter to fish and thousands of invertebrates, protecting the shoreline from erosion and adding to many local economies by being a popular tourist destination.

Because they represent such amazing biodiversity, coral reefs are often called the “rainforests of the sea.” The Great Barrier Reef is the ultimate rainforest of the sea. It is home to 4,000 types of mollusks (clams and other shelled creatures), 1,500 species of fish, 1,500 different sponges, 800 species of echinoderms (star fish, sea urchins and so on), 500 varieties of seaweed, 360 species of hard coral, 200 bird species, more than 115 species of butterflies and more than 30 species of marine mammals.

Image courtesy SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE A very clear view of the Great Barrier Reef off the coast of Australia

Of the 30-plus marine mammal species, some of the most sought after by divers and tourists are dolphins, dugongs, porpoises and whales (Humpbacks, pilot and killer whales). Tourists visiting the Great Barrier Reef also hope to see sea turtles, and they usually aren’t disappointed. In fact, the Great Barrier Reef is a breeding ground for six of the world’s seven species of sea turtle!

Ecosystems within ecosystems… The Great Barrier Reef is known for its huge expanses of coral reefs; approximately 3,000 individual reefs together form what is known as the Great Barrier Reef. However, the Great Barrier Reef is made up of other seabed ecosystems, including algae and sponge gardens, mangrove estuaries, rocky shoals and sea grass beds.

To begin to understand just how incredible the Great Barrier Reef is, you need to know something about coral. The very foundation of this amazing ecosystem all begins with one tiny organism. On the next page, we'll take a look at coral.