6 Facts about the World’s Largest Coral Reef System
- The Great Barrier Reef is the largest living structure in the world. It can be seen by astronauts from outer space. It is composed of over 2,900 individual reefs and 900 islands, that stretch over 2,600 kilometres.
- The reef is located in the Coral Sea, off the coast of Queensland in Australia.
Australia broke away from the Gondwana land mass some 65 million years ago. Australia drifted northward to warmer tropical waters. These waters supported the formation of the coral reefs.
- The Great Barrier Reef began to grow 18 million years ago.
- Billions of coral polyps, which are tiny organisms, form the structure of the coral reefs. The polyps which make up the current reef attached themselves to the ocean floor near the shoreline, 10,000 years ago, in the Ice Age.
- After they died, they left behind their hard skeletons made of calcium. This formed a base for the next generation of polyps. So, only the top layer of a coral reef has living polyps.
- Coral polyps have a symbiotic relationship with tiny plant-like organisms called zooxanthellae. Zooxanthelae live in the cells of the polyp where they can get sunlight. They use the sunlight for photosynthesis and to make food. They share this food with the coral.
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