Great Barrier
Reef
The Great Barrier Reef of Australia' s northeast coast is the world' s longest coral
reef chain and the largest single structure ever created by living creatures.
Scientists believe the Great Barrier Reef formed 30 milion years ago during on ice age
when water levels lower then today. Barrier Reefs are separated from land by wide deep
lagoons. The Great Barrier Reef acts as a sturdy well that protects Australia' s coastline
against Pacific Ocean waves.
Reefs, provide food, shelter and protection for thousands of ocean plants and animals. But
coral reefs are in peril because of water temperatures rising due to increased trapped gases
in the atmosphere.
Pollution from industrial chemicals and pesticides dumped into the ocean, soffocate living
coral. Coral grows only in clear tropical waters between 20° and 28°C; coral polyps share
their protective limestone shell with a type of alga. Coral provides the algae with a home;
in turn, algae supplement the coral' s diet with needed sugars.
When warm water stresses coral, polyps expel algae and the polyps die, living their skeletons.
Coral polyps collect the chemical calcium carbonate(limestone) from seawater and secrete it
around their soft bodies. As polyps die, a new generation "builds" atop their skeletons and the
reef grows larger.
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