British scientists have discovered what triggers one of the most spectacular migrations on Earth – the rush to the beach of the Christmas Island crabs.
The famous red land crabs of Christmas Island, which is situated in the Indian Ocean, spend the dry season lying still in their inland burrows.
But when the monsoon season arrives the crustaceans feel the urge to mate – and are able to trek three miles to the beach. More...
Don't miss: Christmas Island crab invasion!