The Great Barrier Reef

The Great Barrier Reef is one of the natural wonders of the world. Made up of over 3,000 individual reef systems and spanning more than 1,800 miles, it is the only living thing on Earth that is visible from space. The diversity of life found on the reef is truly amazing. It is home to over 1,500 species of fish, 400 types of coral, 200 species of birds and 20 reptiles, turtles, and clams.

Located just off the coast of Queensland, Australia, the reef is a vital part of the country's tourist industry. It provides some of the best diving and snorkelling in the world. There are also several resorts scattered across the more than 900 islands that allow you to stay right on the reef. However, most islands are in a natural state. The reef is heavily protected and any tour or fishing company operating in the reef must adhere to strict laws.

Image is from NASA and is from Public Domain

Coral is a marine polyp (a primitive animal that is related to anemones and jellyfish). It excretes lime, which causes it to form a hard exterior. After the polyp dies, its hard skeleton is left behind. As many of these build up over time, they form the reef. New polyps grow on top of the old ones, adding to the reef.

Certain conditions must be present in order for coral to grow. The water temperature must be a minimum of 17.5 degrees Celsius. The water also needs to be clear so that sunlight can penetrate the surface. Coral only grows in salt water and it will not grow any deeper than 30 metres below the surface. It also will not grow around river mouths. Because of these conditions, the Great Barrier Reef stops north at Papua New Guinea near the mouth of the Fly River and south where the water temperature becomes too cool.

This is one person's experience diving on the reef. It's a really nice video of what you might experience, even as a beginner. If you're thinking of visiting the reef, remember that you don't need any experience scuba diving or snorkeling to enjoy it. Companies that take you out to the reef provide life jackets, so you don't need to be a strong swimmer. Also, I had never snorkeled before and picked it up fine (and I have heard that from other people, too).

The Great Barrier Reef is one of the most popular tourist destinations in the world. With its predicted demise in the next 20 or so years, many people are trying to get their trip in soon. If you haven't been yet, make sure it's at the top of your destination list.

During the last ice age, the sea level was likely 100 metres lower than it is today. 18,000 years ago, the Reef was dry land and many of the islands we see on it today were hills. When the ice began to melt, the sea levels rose. By 12,000 years ago, the coastal plain was a submerged continental shelf.

Even before the last ice age, other reefs had existed in the same location. The outer edge of these reefs had become submerged by 8,000-9,000 years ago. By 6,000-7,000 years ago, the sea had stopped rising and reached its present level. The current Great Barrier Reef could now use the ancient reefs as a base and begin its journey to the remarkable organism it is today.

There are two types of islands. The first type used to be the tops of mountains. Over time, the sea level rose and these mountains slowly flooded. When the water levels stabilized, the tops of the mountains remained, forming hilly islands. The second type is formed from the reef itself. When areas of the reef became above sea level, the coral died. The water gradually ground down the dead coral to form sand. Eventually, vegetation grew on these islands, forming what we now see today. These islands are low-lying as opposed to the hilly islands left behind by a previous age.