CORAL REEFS

Coral reefs are spectacular explosions of life and colour with a mixture of sponges, sea fans, soft and hard corals acting like underwater cities -  bustling homes to hundreds of different species of fish and many other invertebrates including crustaceans, sea urchins and starfish.

Coral reefs are actually made up of millions of tiny animals, called POLYPS, that are related to sea anemones.

As they grow these polyps divide and each one secretes a limestone coral 'skeleton' around itself. Building up on top of each other these coral skeletons gradually form into reefs.

Individual reef colonies may be over 1,000 years old and are home to vast numbers of different species - from microscopic invertebrates to large sharks.

The reefs support an entire food chain which begin with the tiny individual polyps which form the coral.

Although they are vegetarian, parrotfish, with their hard beak-like mouths, rasp off pieces of this living coral to get to the algae which inhabit them.

The reefs are also home to a dazzling variety of fish species like Wrasse, Surgeonfish, Butterflyfish, Angelfish, Pufferfish and moray eels.

Competition for space and food is so intense that activity on and around the reef continues 24 hours a day - different species have evolved into 'night' and 'day' shifts to maximise their share of this precious habitat.

Some reefs are believed to have been growing incredibly slowly for more than 5,000 years.

For all their apparent strength coral reefs are actually incredibly fragile structures - even the lightest touch from a careless snorkeller's fin, hand or equipment can easily crush and kill the living coral polyps.

Marine experts estimate 10% of the world's coral reefs are dead and many more are in serious decline as a result of human impact.

However it is not all doom and gloom and we can all play an important role in helping to save these magical underwater rainforests from destruction.