Christmas Island Red CrabGecarcoidea natalis
The Christmas Island red crab is a species of land crab that is unique to Christmas Island, Australia, in the Indian Ocean. Christmas Island red crabs are well known for their annual mass migration in which they move in millions to venture from land to the ocean to mate and lay their eggs.
Over 12 years
Rainforests, coast lines and gardens
3-4 weeks in larval stage (A single female can lay up to 100,000 eggs)
Yellow crazy ant and coconut grabs. During larval stage: manta rays and whale sharks
HabitatChristmas Island red crabs live in the dark forests in self-dug burrows where they are sheltered from the sun. During the dry season, the red crab will cover the entrance to their burrow to maintain humidity. Juvenile Christmas Island red crabs do not live in burrows but instead hide in rock outcrops, fallen tree branches, and other forest floor litter. The famous migration of the Christmas Island red crab begins at the start of the wet season (October or November) as it allows the red crabs to travel along the forest floor to the ocean without the worry of drying out. During migration, the red crabs leave their burrow and make the journey to the coast where male red crabs dig out new burrows where the mating takes place. The males then return to the forest and the female red crabs remain in the temporary burrow until it is time to lay their eggs.
It is thought that decreasing the amount of access the yellow crazy ants have to the honey-dew will result in lower ant population and bring back the success of the Christmas Island red crab. 300 micro-wasps from Malaysia were brought in to help curb the dew production of the lac scale insects. The micro-wasps are a parasitic species that lay eggs within the lac scale, which eventually kills the lac scale and ceases dew production.
Since the introduction of the micro-wasps, the Christmas Island red crab population is on the rebound. Red crabs have been able to dig their mating burrows, which would have been otherwise overtaken by yellow crazy ants, and carry through with egg-laying.
Christmas Island red crabs have also been named a protected species and harming them is illegal. The building of “crab crossings”, walls and bridges red crabs can walk over rather than cross the road, on Christmas Island is a precaution taken to avoid human and red crab interaction. Major road closures and detours are also taken during the migration season.
How You Can Help
Christmas Island red crab migration season is one of the Island’s biggest tourist attractions and although the population of Christmas Island red crabs are on the rebound, but you can still help to ensure the red crabs populations remain healthy. If you are ever in the area during migration season, please:
- carefully walk among the sea of red crabs,
- pay attention to road closures and redirection notices,
- do not pick up or feed the red crabs, and
- respect the space of the red crabs
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