Claw-some moves as millions of red crabs begin mega migration

Tens of millions of red crabs have begun their annual migration across Christmas Island, near Australia.

The spectacular yearly event sees around 50 million red crabs travel from their homes in the island forests to the ocean - to lay their eggs.

Special crab bridges have been built on the island to help the crustaceans get around tricky obstacles such as roads, and local radio stations provide residents with an update on the mass crab movements.

The invertebrates all leave their burrows at the same time - when the Moon is in its third-quarter phase - and with the first rainfall of the wet season.

Why do the red crabs of Christmas Island do this?

Crab bridges like this one, help the crabs to safety cross roads

You might be wondering what causes millions of crabs to move from one end of the island to the other at the same time?

Well, the crabs are travelling to the ocean to mate and lay their eggs at the best possible time for all the eggs to survive - in perfect tidal conditions because of the Moon.

They also need the rain for the journey so they don't dehydrate on the trip.

Did you know - each female crab can produce up to 100,000 eggs!

Once they've mated, the female crabs stay in little burrows on the beach for a few weeks whilst their eggs grow.

When the Moon reaches its final quarter and the tide is high, the female crabs will head into the water just before dawn to lay their eggs - which hatch straight away into tiny crab larvae.

Then, with that done, the female crabs head back home into the forests.