the great barrier reef - visitor information

In the clear warm waters of tropical Queensland in Australia, lies a wonder that has to be seen to be believed. As if experiencing the beautiful climate and atmosphere of the region itself were not attractive enough, visitors are amazed at the stunning pleasure of the Great Barrier Reef. Please visit the www.great-barrier-reef.com web site for more information on accommodation, tours and activities.

What is The Great Barrier Reef?

A coral reef is formed when millions of tiny animals called polyps build a hard limestone skeleton as they live and die, each new layer building on previous layers to form coral rock in a variety of formations. These structures provide a haven for a variety of other sea creatures, producing a community of incredible diversity and colour and filled with remarkable relationships.

Coral reefs grow in shallow water in the warmest parts of the world. Coral generally cannot survive below 20 degrees Celsius explaining why we find the worlds largest coral reef in the warm shallow seas off the northern coast of Australia. Named "The Great Barrier Reef" this underwater wonderland stretches for more than 2000 kilometres and can even be seen from space.

What is coral?

Although appearing "plant-like" corals are actually comprised of tiny animals called polyps. The polyps live in a skeleton of limestone they create themselves by secreting calcium carbonate. The polyp itself is a soft organism with a base, a stomach, and a mouth opening surrounded by tentacles. The polyps are usually retracted within the skeleton by day, expanding at night to wave their tentacles to catch microscopic animals called plankton. The tentacles use venomous stinging cells to kill small prey and also for protection from predators.

Corals belong to the phylum Coelenterata which include jellyfish, coral polyps and sea anemones. There are about 9500 species in this group. It may be surprising to realise the similarities between animals such as jellyfish and coral which are both basically a stomach-vessel with poisonous tentacles used to catch prey.

One of the most amazing facts about coral polyps is the incredible relationship they have with algae known as "zooxanthellae". In this symbiotic relationship the polyp provides the environment in which the algae can live and in return the algae carries out photosynthesis, using sunlight to create sugars used to give the polyp energy. The zooxanthellae also contributes to the spectacular colours of corals as the algae's chlorophyll is combined with fluorescent yellow, blue, orange, violet and brown pigments.

Most polyps are less than 2.5cm in diameter but some are as much as 30cm in diameter. Species of coral include Staghorn, brain, honeycomb and mound coral.

What is Coral Spawning?

Each coral polyp has both male and female sexual organs. Coral reproduction has a number of forms, two forms of sexual reproduction as well as asexual reproduction.

"Brooder" corals fertilise and incubate an egg internally before later releasing it into the ocean. Alternatively other corals use a process called "spawning" in which all the corals in a region release eggs or sperm on the same night. The timing of this event is synchronised by the phases of the moon and results in an awesome display.

The larva that result from either of these processes are called "planula" and drift on the ocean surface for a few days before settling to the seabed and attaching to anything solid. The young polyps then build a structure by secreting calcium carbonate producing the characteristic hard skeleton in which the polyps live.

Polyps that form a colony also reproduce through a process called "budding" in which a bud from a parent polyp secretes its own skeleton. As new polyps develop, old ones die, leaving behind their skeletons.

What are the enemies of coral?

Some fish species are immune to the polyps poisons or protected from the hard skeleton.

Unfavourable sea temperatures, sea levels that are too high or too low, and over exposure to harmful radiation from the sun are all threats to the environment that coral requires. There are also concerns that water run-off from the mainland near the reef can carry farm fertilizers and chemicals that could be damaging to the reef ecosystem.

One of the biggest threats that the reef faces is the "Crown of Thorns" starfish. This predator surrounds a coral structure with its stomach and eats it alive by dissolving the organic material with digestive enzymes.

What other creatures inhabit the reef?

The Great Barrier Reef is home to an awesome array of sea life. There are about 1500 kinds of fish known to live in the reef region including angelfish, cod, manta rays, mackerel, butterfly fish, and surgeon fish. Three species of marine turtles, the green, hawksbill, and loggerhead, are found in reef waters. They breed on beaches of some coral cays. 4,000 species of shellfish live on or near coral reefs. Other animals that live in reef waters include crabs, shrimps, crayfish, sea urchins, sea stars, sea cucumbers, soft corals, sea fans, sponges, sea anemones, and worms.

Viewing the reef.

There are a number of ways to take in the spendid views the Great Barrier Reef has to offer including snorkelling, scuba diving, glass bottom boats, semi submersibles and underwater observatories.

Snorkelling involves using goggles and a breathing tube called a snorkel to allow the snorkeller to swim on the waters surface and view the coral below without needing to come up for air. Flippers also make swimming easier. As the waters are quite shallow snorkelling provides a way to get quite close to the coral and fish life for a great experience.

Scuba Diving goes a step further and allows the diver to descend into the heart of the reef. This provides the most spectacular experience allowing close access to some reefs otherwise inaccessible. It does however require certain health requirements and training certifications.

Glass bottom boats and semi submersibles allow passengers to see the reef through glass windows while the operator points out things of interest. Similarly, underwater observatories are fixed structures allowing visitors to view the reef through windows under the water.

How to get there.

Australia is a safe and friendly place and its people welcome visitors to share the experience of the amazing place in which they live. This web site has been brought to you by a local Australian company that assists visitors to Australia with personalised travel itineraries. TravelOnline provides traveler with access to a number of professional travel consultants who actually live in Australia and can give the best local advice to visitors coming into the country.

Whether you want to see The Great Barrier Reef, Queenslands tropical islands, Sydney, the outback or any of the other world renowned attractions of Australia, the TravelOnline staff can assist you with accommodation, tours or vehicle rentals. Please visit the www.great-barrier-reef.com web site for more information on accommodation, tours and activities.