The Red Crabs: Amazing Phenomenon on Christmas Island

Christabel, Fiona, Cat and Connor in November 2021 … with frontispiece pix  from Samantha Wright

One of the top ten natural wonders of the world, according to David Attenborough, is happening right now in the thriving rainforests and deserted beaches of Australia’s Christmas Island. Christmas Island is globally significant, home to a wealth of unique and rare sea birds, land crabs and marine life. There are few comparable unspoiled tropical environments left in the world.

Once a year, this uniqueness is on full display as millions of red crabs emerge from the forest and make their way to the ocean to breed, swarming across roads, streams, rocks, people’s homes, and beaches.

Right now, we have a massive opportunity to ensure future generations can continue experiencing this natural phenomenon.








The Australian Government is considering creating a new marine park around this tropical paradise and we need you to add your name in support! If there was any question about the need to protect this beautiful part of the world, keep scrolling to see some photos from the island and find out more about the mass crab migration.

The annual migration starts with the first rainfall of the wet season, usually in October or November, but sometimes as late as December or January. The exact timing and speed of the migration is determined by the phase of the moon. Red crabs always spawn before dawn on a receding high-tide.

Remarkably, they know exactly when to leave their burrows to make this lunar date!

Male crabs usually arrive at the sea first, digging burrows and fighting for real estate as the females begin to arrive. After the mating has finished, the male crabs take a dip in the ocean and head back into the jungle whilst the females stay behind to produce up to 100,000 eggs! As the moon reaches its final quarter, the egg-laden females leave their burrows and head to the shoreline to release the eggs into the sea for hatching. The vast majority of larvae never make it out of water – instead they’re eaten by fish, manta rays and whale sharks who visit every year to take advantage of the annual feast.

Most years, no or very few baby crabs will emerge from the sea at all. But once or twice a decade, a huge number will survive, which is enough to maintain the island’s large red crab population.

Every year, as millions of red crabs emerge from the Christmas Island forest and begin marching towards the ocean, we’re reminded of the importance of protecting this unique marine environment.

Right now the Government is proposing a massive marine park for Christmas Island and its neighbour the Cocos (Keeling) Islands. This is our chance to protect this unique part of Australia

Please add your name today and help create two brand new Christmas Island and Cocos (Keeling) Islands marine parks. Thanks again for all that you do and we look forward to continuing to work with you to protect this unique part of the world.

Kind regards,

Christabel, Fiona, Cat and Connor

Save Our Marine Life

Thanks to our amazing supporter and Christmas Island local Samantha Wright (saga_the_sony) for sending through photo of the crabs.

AN EMAIL NOTE from Michael Obeyesekere in Australia, 17 November 2021:

The red crab lives on land. However  they only lay eggs and breed in the sea. I have witnessed this phenomenon. Thanks for sharing…..  Michael.

A THUPPAHI THOUGHT: as usual all the hard labour is performed by females !

1 Comment

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One response to “The Red Crabs: Amazing Phenomenon on Christmas Island


    Another amazing breeding phenomenon.

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