Great Barrier Reef

Reef facts and figures
The Great Barrier Reef contains over 2,900 reefs, which includes 760 fringing reefs, and 300 coral cays. There are also 618 continental islands, which were once part of the mainland.
As the world's largest coral reef ecosystem the Great Barrier Reef is home to approximately:
1,500 species of fish
400 different types of coral
4,000 species of molluscs (like clams and the sea slug)
500 species of seaweed
215 species of birds
16 species of sea snake
6 species of sea turtle
whales coming during winter

Rise of the corals
All though the corals are tiny invertebrate sea animals, they are able to create enormous constructions. During 25 million years they made a 2,000 km long reef along the northeast coast of Australia, which encroaches an area comparable with British islands and form a self-reliant submarine world. Is formed by 2,500 individual corals, which lay very close to each other. For bigger objects is the invincible natural barrier.
A corals are made up of thin layer of living animals called polyps, which secrete a chalky, limestone skeleton as they grow. Coral colonies grow as the polyps divide and multiply in a process known as budding. After several million of years the coral reef increase its size to the hundreds of kilometres and become nearly as big as the Great Barrier Reef is. Corals feed mostly on plankton and grow in warm climates, where is clear salt water, sunlight and no pollution.
A coral reef is a natural barrier made the bodies of living and dead coral. It is normally just below the surface of the water. The coral reef is formed of two parts. The white part is made from the bodies of zillions and zillions of polyps, which have died over hundreds and thousand years. The colourful part is the living part of the coral reef. It is made up of living polyps.
Some scientists also affirm that the Great Barrier Reef is the biggest living creature on the world. And they are right - when some part of the coral reef die, immediately will be offset by new coral colonies. The regeneration ability is enormous.

Who damages the reef?
The main parasite is the Crown of Thorns starfish, which is over manning there and destroys the coral reef by eating it. If it left unchecked, could dominate the reef and break the entire ecosystem.
But not only this animal destroy the Great Barrier Reef. For example people with their carelessness do frequently far more damage than anyone else. There are some examples, how do people damage the reefs:
· Walking on them
· Drooping anchors on them
· Dragging diving gear over them
· Breaking them and taking them home as souvenirs
· Knocking grounding boats on them
The reef also suffers, because of the pollution. Sometimes sewerage, oil spills, fertilisers or pesticides could pollute the water.
In spite of thousands species of fish, there impend the over fishing. Some fishermen also don't respect any rules and fishing with using explosives, poison or drag nets.

Protection of the nature
In the twentieth century was this region threaten by Asian fishermen, who were there systematically catching the fish and so Australia ratified in 1938 a strict ban of fishing in this area. This law was later many times diffused, changed and edited, but the main idea of protecting the nature survive.
Today is 98 percents of the coral world protected by national park called Great Barrier Reef Marine Park established in 1975. It is the world largest marine protected area in the world. It is approximately 348,700 square kilometres (you can compare it with the area of Czech republic - 79,000 km2) in area and 2,300 kilometres long, running from just north of Bundaberg to the top of the Cape York Peninsula.
With the founding of national park, of course many forms of damaging the reef disappeared, but e.g. the carelessness of visitors could not change.

The submarine life
The Great Barrier Reef isn't only the biggest natural construction in the world, but is also full of hundreds of colours. This use many fish to hide in the coral reef before their enemies, because of their protective coloration.
The coral reef has limited live conditions. That means that every gap has to be fill with some animal and that fish lives very close to their enemies. Small fish could be hidden into the coral; bigger ones mostly find some gap or ledge.
Unforced predator is a shark. Specifically gray cliffy shark but isn't usually there, because sharks prefer open sea.
A lot of animals also live in the symbioses. For example the "cleaning fish", which live with bigger fish, eat things, which drops and reciprocate deprive it of parasites and redundant scales.
The Great Barrier Reef is a softly balanced ecosystem and infestation of one of its part could damage it.