Billions of baby red crabs return to Christmas Island… Sometimes

We mostly hear about the yearly migration of adult red crabs on Christmas Island.

And we therefore forget about the baby red crabs that sometimes, because it is not frequent at all, invade streets, beaches and forests after their insane trip in the Ocean waters.

For the second year running, in 2015, there has been a fantastic return of baby red crabs from the sea and onto Christmas Island.

The adult crabs spawned in the sea four weeks ago and now the baby crabs are making their way back to start life on land and in the island’s forests.

And this is pretty rare as it is not uncommon for a number of years to pass with no, or very little replenishment of new crabs.

The numbers of returning crabs in 2015 was beyond any expectations. The east coast of the island has been particularly good with billions of crabs coming ashore at Dolly Beach, Greta Beach and Ethel Beach.

The crabs have had to dodge many predators while in the sea and not all will survive the challenges ahead of them as they find the best places to live in the forest.

However, two very good returns in a row bodes well for the island’s crab population.

So what about 2016?

Spawning can happen as early as October and as late as January but November and December are the more usual months. The possible spawning dates for 2016 are:

25/26/27 October 2016
24/25/26 November 2016
24/25/26 December 2016

The migration comprises a sequence of events that follow on from one and other in a distinct order – a following sequence cannot be undertaken without the crabs having accomplished the preceding.

1. The crabs will migrate to the coast where the males will dig mating burrows and they will mate. After mating, the males will commence their return migration. The females will brood their eggs for 12-13 days before emerging from the burrows to commence spawning.  The females will commence their return migration immediately after spawning.
2. The eggs hatch into free swimming larvae immediately after they are drooped into the sea.
3. The larvae grow through several stages in the ocean for over four weeks before emerging from the sea to become tiny crabs.

Let’s hope that this insane El Nino will not have nefast consequences on the 2016’s hatching and baby red crab migration.

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