Wednesday, May 18, 2011

Crab Migration:Yes, i said Crab Migration!

If you were to say the word migration to any safari specialist, the first thing they would tell you is that it happens during July - August and they would automatically be referring to the annual wildebeest migration that happens in the Maasai Mara. However, i came to learn that we are not the only one's who seem to have a migration......Christmas Island have one too! A crab migration!

At first, i thought it was a joke because i had never heard of a place called Christmas Island!Yes, it is an existing place.A small Island (dot) in the Indian Ocean with its closest continent being Australia.It is actually north west of Perth,Western Australia.

This amazingly strange migration occurs around the months of October - November where the Christmas Island Red Crabs move from the rainforest into the ocean to allow breeding. The males lead the first wave of the downward migration then 5-7 days later the females follow and at most time out number the males! It is said that the crabs replenish moisture by dipping in the sea, then the males retreat to the lower terraces to dig burrows.

The density of burrows is high (1-2 per square metre and fighting occurs between males for burrow possession. The females move to the terraces and mating occurs, usually in the privacy of the burrows that males have dug and fought for. As mating, and fighting, abates, males dip again and begin returning inland. They move quickly, reaching the plateau in only 1-2 days.The females produce eggs within 3 days of mating and remain in the moist burrows on the terraces for 12-13 days while they develop. The eggs are held in a brood pouch between their extended abdomen and thorax.

Fact: A single female can brood up to 100,000 eggs.


  1. Wow! That is so interesting. Thanks for sharing it. Kind of gives me the willies... I guess you need to be careful when sun-bathing during this time of year : )

  2. I don't know how I would feel if I saw crabs walking on the road migrating elsewhere. That is too funny and very interesting! Here on the west coast of the US, no such thing besides the birds, whales and dolphins. I don't know how we'd handle crabs on the road.

  3. Whoa! They can crawl to my house anytime. Of course I'll be waiting with a big pot and a large wooden spoooooooon. :P


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