The annual red crab mass migration ( around 100 million animals ) to the sea to spawn has been called one of the wonders of the natural world . This takes place each year around November -- after the start of the wet season and in synchronisation with the cycle of the moon .
The annual red crab mass migration ( around 100 million animals ) to the sea to spawn has been called one of the wonders of the natural world and takes place each year around November ; after the start of the wet season and in synchronisation with the cycle of the moon .