漂流者 12

You might think it would be easy for a fish to swim between these small islands

But not so

You wouldn't find these little fish in deep water

The open ocean beyond their shallow reef is, in fact, a huge barrier

So how did all these fish come to be here

Colonising new reefs is a challenge faced by fish across the South Pacific but they have a simple solution

Once a year, thousands of groupers gather on the reefs

With the coming of the full moon, an extraordinary event unfoylds

They spawn

A female darts up and releases millions of eggs

quickly followed by the males, who jostle to fertilise them