Creatures of...the Great Barrier Reef

Ian Somerhalder Foundation

The Great Barrier Reef

The Great Barrier Reef, located in the Coral Sea off the coast of northeastern Australia, is home to one of the most diverse collections of sea dwelling creatures in the world. The world’s largest coral reef is the largest living structure on the planet, so large that it can be seen from outer space. The reef itself is approximately 500,000 years old, but it has changed, grown, and receded since then due to the changes in sea levels. The current structure is approximately 6,000 to 8,000 years old. 2 Two thousand species of fish, four thousand species of mollusks, and six of the world’s seven species of sea turtles, as well as sharks call the Great Barrier Reef home. 1

The reef structure itself is made up of millions of tiny organisms that make up the coral formations. 3 There are approximately 350 species of hard coral that make up the over 2,900 coral reefs. The structure includes canyons, channels, slopes, and beds of sea grass. So just how many diverse creatures call the reef home? Thousands of sponges, worms, over eight hundred different species of starfish and sea urchins, and more than thirty species of marine mammals live in the reef, and that’s just below sea level! Twenty-two species of seabirds live on the islands within the Great Barrier Reef marine park. Many endangered species can also be found in the reef-along with sea turtles that breed on the reef. Humpback whales also travel from Antarctica to give birth in these waters. 4 5

Creatures of the Great Barrier Reef

No written word could ever do justice in explaining the numerous and diverse creatures living in the reef. Some creatures are commonly known and recognizable while others are not. And just like in any ocean, while many of the creatures are not harmful, some creatures very well could be harmful to humans. For example, the Blue Ringed Octopus is tiny, about the size of a golf ball, and carries a poison (with no known antidote) powerful enough to kill an adult human within minutes. Its rings “glow” an electric blue when it has been provoked or is on the defense, which makes it especially dangerous to children, or those who don’t know any better and may pick it up due to its size and attractive nature. Most Blue Ringed Octopus live in rock pools and coral. 6

One of the most well known symbiotic relationships in the creature kingdom, the relationship between clownfish and the sea anemone, takes place within the Great Barrier Reef. The sea anemone is a stinging polyp, closely related to coral and jellyfish. The Clownfish has a protective mucus layer that makes it immune to the sting of the anemone and lives within the tentacles of the anemone. The anemone provides the Clownfish protection from predators and eats the scraps from the Clownfish’s meals while the Clownfish cleans the anemone of algae.

One of the most colorful creatures found swimming around the reef is the Parrotfish. It has a “Parrot-like” beak which allows it to bite off hard coral that it then chews and feeds on before expelling them in what is considered a “stream of coral dust particles.” Parrotfish can be found in a variety of different colors including blues, greens, and yellows, and they even have different patterns! This allows them to easily blend into the reef background.

The Humphead Maori Wrasse is, unfortunately, endangered due to it being considered “tasty.” In fact, it is a prized eating fish in Southeast Asia. They have been a protected species since 2003. They prefer to live in the most offshore reef systems where steep slopes and drop offs can be found. They have a large hump on their head that grows as they age – the bigger the hump, the older the Maori Wrasse! 9

Threats Against the Great Barrier Reef

There are many things threatening the biodiversity and survival of the Great Barrier Reef and its inhabitants, with the biggest threat being that of global warming and climate change. The Great Barrier Reef and its creature companions can be overwhelmingly affected by even the slightest change in sea temperature. How slight? A sea temperature rise of even one or two degrees can cause coral bleaching and death of sea life worldwide.

The Great Barrier Reef is also at risk of overfishing, even by natural predators such as the Crown-Of-Thorns sea star. This creature feeds on hard coral, and by poisoning them and feeding off of them, it can destroy an entire reef. 3

Another threat against the reef comes in the form of toxins –fertilizers, pesticides, and toxic chemicals, amongst other things, that we use every day. These toxins run into rivers and eventually into the Great Barrier Lagoon where they threaten the plants and creatures of the Reefs. Many of these pesticides have been found in dolphins and dugong. 10 To coordinate projects and partnerships to help improve the quality of the water in the Great Barrier Reef, the Reef Water Quality Protection plan was created. You can learn about the Reef Water Quality Protection plan here.

Overfishing and pollution can have devastating effects on all ocean life, including that of the Great Barrier Reef. Many species living within the Reef system are unable to adapt to these changes and are slowly becoming rare or threatened species. 11 We need to preserve and protect them!

How To Help Preserve and Protect the Great Barrier Reef

Keeping the Reef ecosystem healthy and diverse allows it to better withstand, recover from, and adapt to the different stresses that it may encounter from nature and man. There are numerous ways that we can all help to preserve and protect the Great Barrier Reef and all of the creatures living in it!

If you are vacationing at the Great Barrier Reef…
• Never touch the coral! As beautiful as it is, you can easily destroy it! You also run the risk of getting hurt when touching it because it has hard sharp spines.
• Don’t buy shells and coral as souvenirs. These were most likely taken from the reef, and while your purchase might be beautiful, it is aiding in the destruction of the reef.
• If you go diving, learn the proper ways in doing so in order to avoid inadvertently damaging the reef as you swim through it. Don’t stand or rest on living coral.
• Don’t litter! As we’ve learned, what starts out on the beach all too often winds up in the water and can have devastating effects on the creatures!
• Don’t feed the fish. You never know if what you are feeding them is harmful and you might not find out until it’s too late.
• Don’t ride sea turtles or Manta rays. Enjoy these gorgeous creatures at a distance, but trying to ride them can injury both them and you!
• If you are taking a tour, make sure that it has an Ecotourism logo. That means that it operates in a sustainable manner. 12
• If you are boating, anchor away from any living coral and slow down so that you don’t unintentionally injure one of the creatures living the water.






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