火山列岛 13

A single fish can chew its way through a staggering five tonnes of coral a year.

Smaller parrotfish, colourful cousins of the bumphead,are also at it.

But they all give a little back

as the ground-up coral comes out as sand.

This is island building of a different kind.

So some of the Pacific's most elegant beaches

have sprung from a less than stylish birth.

Above the water, time seems to stand still.

But the Pacific islands are always changing, if slowly.

This is Bora Bora,

a volcano in what could be called "late middle age".

The sloping flanks have slipped further into the sea,

pushing the reef away from the shore.

A lagoon is formed.

It's a patchwork of coral outcrops and sand.

Protected from the powerful waves of the surrounding ocean,

all kinds of animals take refuge in these calm, shallow waters.