Great Barrier Reef - about the reef
By Alan
Coral reefs are resistant structures, built from the debris of small
marine organisms. The major part of a coral reef is composed of a
limestone block from the skeleton and fragments of shells of dead
animals that lived on the reef. The wildlife which is very diversified
lives in the surface layer of the reef. When these animals die, their
skeletons and solid debris will consolidate the base and participate in
the growth of reef.
The bodies of reef builders are hard corals who manufacturer reefs
secreting a skeleton in the form of aragonite, a mineral containing 98%
to 99% of calcium carbonate. .
 The young polyp produces a limestone base, a sort of chalice used as
foundation. Corals form, and accumulate, large ensembles, the reefs. The
fish that graze the surface of the reef produce sand that fills the
crevices. It is cemented together by algae that give the reef its
strength. The reefs can not be formed anywhere, the salinity,
temperature, clarity, brightness and oxygenation of the water must meet
certain conditions.
The Great Barrier Reef is a huge reef that covers an area of 230 000 sq.
km and runs for about 2 300 km, east of Australia’s mainland, along the
coast of Queensland. The reefs represent a strip 20 km wide, there are
tens of thousands of years of accumulated corals. The Great Barrier Reef
is the largest structure erected by living creatures, including humans.
The Great Barrier Reef changes every day, always growing always
changing. “The” reef is actually a mass of approximately 2 900 reefs,
including 300 islands, it offers an extraordinary submarine spectacle.
The life forms are incredibly diverse with residents such as aquatic
weeds, sponges, molluscs, turtles, and countless fish with vivid colours
that blend with all kinds of corals. Whales of Southern seas and also
marine turtles enjoy the protection of these reefs and come to give
birth in their protected waters.
If human activity is a clear threat, the reefs are subject to other
attacks, the most destructive of these is the star or black crown of
thorns is a starfish a coral-eating animal. The crown-of-thorns starfish
operates in a huge group can destroy an entire reef. This starfish has
up to 17 arms covered with poisonous spines. It dissolves the coral
polyps through the digestive juices and eats’ them by suction.
The GBR is one of the world’s truly great attractions; defiantly on most
peoples “see before you die” list. Its magnificence is almost beyond
belief, with its stunning beauty and plentiful marine life as well as
its endless beaches and crystal clear waters the Great Barrier Reef is
everything you imagine and so much more. |
