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Media Release
Greg Hunt MP
Parliamentary Secretary to the Minister for the Environment and Heritage

23 December 2005

Hundreds of thousands of red crabs return to island for Christmas


Greg Hunt MP Parliamentary Secretary for the Environment with responsibility for Christmas Island National Park announced today that hundreds of thousands of infant red crabs have migrated onto Christmas Island - hatching from eggs at the shoreline after two weeks of incubation in underground burrows and around 4 weeks spent in the shallows developing from larvae into crab form. The crabs hatch every year after midnight towards the end of December - the timing of their hatching coinciding with the last days of the lunar week of November and midnight tide.

"The phenomenon behind the female crabs knowing exactly when the last days of the lunar month are, and again, how they know that the very early morning creates the calm tidal conditions needed to spawn their eggs into the sea, is unknown by science," Mr Hunt said.

Mr Hunt said after the millions of adult crabs migrate from the rainforest to the shoreline for mating, the females spent two weeks incubating their eggs in burrows dug for them by the males. Then they moved onto the rocks at the water's edge, or at the top of the few small beaches on the island before spawning the eggs into the ocean.

The female crabs will not spawn eggs into the sea during the day because the waves are larger and stronger than after midnight - and the crabs can't swim.

"If the waves are too big the infant crabs get washed off the shore and either drown or get eaten by predatory eels, manta rays and whale sharks.

"This event is extremely unique - both due to the fact that it is a natural annual event that has not yet been explained by science, and that it only happens at one place on earth, Christmas Island."

Mr Hunt said despite millions of adult female red crabs migrating from the dense rainforest to the shoreline and the millions of eggs spawned into the sea, many years can pass without many crabs returning.

"This year, the annual red crab migration has been very successful and we have seen the return of the infant red crabs, travelling in groups of thousands, up into the rainforest from the beach.

"The entire island is literally covered in infant red crabs making their way along - the locals are extremely used to the crabs being part of their daily lives during the adult migration and again during the return of the infant crabs and take great care to allow them to travel as safely as possible.

It really is a spectacular sight to witness," Mr Hunt said.

Media contact:
Kristy McSweeney (Mr Hunt's office) 0415 740 722

Commonwealth of Australia