Christmas Island is an Australian territory in the Indian Ocean known for its famous residents – found no where else in the world – the Christmas Island Red Crabs.
Christmas Island Red Crabs are around 4.5 inches (11.6 cm) and commonly found in the island rainforests.
Renowned for their annual mass migrations of around 50 million crabs, they begin their journey to the ocean for breeding during the wet season in October-December.
The timing of the migration is in sync with the lunar cycle. During the last quarter of the moon, when there is the least difference between tides, it is safer for the females to release their eggs.
A single female can lay up to 100,000 eggs, they hatch as soon as they come in contact with the ocean. Swarms of larvae are washed out to sea where millions of them become food for plankton eating filter feeders like manta rays and whale sharks.
After about a month at sea, the larvae will grow through several larval stages and develop into a prawn-like form known as megalopae. They gather close to the shore for one to two days and become what finally resembles baby crabs.
Measuring only 0.19 inches (5mm), billions of baby crabs make their way back to the rainforest plateau, eventually starting the cycle over again.
Christmas Island Red Crabs are scavengers, eating mainly fallen fruits, flowers and leaves, but also carrion (the remains of dead animals).
They are usually found hiding in burrows or under leaves to help conserve moisture – if the crabs dry out, they’ll die.