Red crabs migrate through in the middle of the island – grated parts of the road allow the migration to avoid being crushed by cars and ensure they travel under the roads.

    Photo Credit: James D. Morgan

    Female red crab spawns in the early hours on Ethel Beach. Once the crab eggs are dropped, the females begin the march back to the centre of the island. Meanwhile, after coming in contact with the sea water, the eggs hatch immediately and release clouds of young larvae.

    Many of these do not survive as they are eaten by predators, but those that do, develop into prawn-like animals called megalopae. These gather in pools close to the shore for several days to finish the process of turning into young crabs. Leaving the water, the tiny baby crabs measure just 5 mm across. However, this doesn’t stop them from following in their parents’ footsteps and beginning the long march again.

    Photo Credit: James D. Morgan

    On the centre line of the main road through the island a red crab (Gecarcoidea natalis) makes it way across on its migration path to the sea. Each year millions of crabs make the month-long migration to the sea, sometimes travelling up to 9 km.

    Photo Credit: James D. Morgan

    Workers from National Parks and Wildlife on Christmas Island are supported during the red crab migration by locals as they try their hardest to keep roads clear for cars and buses to pass through.

    An Australian territory, Christmas Island lies some 2600 kilometres north-west of Perth in the middle of the Indian Ocean. While just 1500 people live there, it is home to an estimated 120 million crabs.

    Photo Credit: James D. Morgan

    Local schools and the general community designed posters to ensure people are aware of the migration and drive slowly. Along the way, from the interior of the island to its coast, they face numerous hazards. While the locals do the best as they can, according to ranger Max Orchard, each year up to half a million crabs never return.

    Many of these casualties fall under the wheels of vehicles as they attempt to traverse local roads or are attacked by yellow crazy ants.

    Photo Credit: James D. Morgan

    Red crabs (Gecarcoidea natalis) on Christmas Island swarm a tree on their annual migration to the sea to breed. Once the males arrive at the sea, they dig special burrows, where mating takes place once the females arrive.

    Afterwards males begin the arduous journey back inland while the females remain in the burrows for about two weeks, laying eggs and waiting for them to develop. The eggs are held in a brood pouch – located between the female crab’s abdomen and thorax – which can hold as many as 100,000 eggs.

    Photo Credit: James D. Morgan

    A young boy at Flying Fish Cove takes a closer look at the hundreds of female red crabs waiting to spawn in the early hours. These are endemic red crabs (Gecarcoidea natalis), which spend most of their time living in burrows on the rainforest floor in order to avoid drying out in the fierce sun. But when the time is right – according to the tides and phases of the moon – they embark on the journey of their lives.

    Photo Credit: James D. Morgan

    Crabs meander across the traffic lights at Flying Fish Cove on the Australian territory of Christmas Island. Along the way, from the interior of the island to its coast, they face numerous hazards.

    Photo Credit: James D. Morgan

    Locals are kept up to date with road closures so they can avoid the main routes of the red crabs as they migrate to the sea. The mass migration is headed by the males, which are quickly followed by the females. The crabs spend several painstaking weeks crawling to the ocean, which can be as far away as 9 km.

    Photo Credit: James D. Morgan

    Red crabs make their way through the rainforests throughout the island and are aided by walls which the Christmas Island National Parks and Wildlife put up to ensure they get to the right spots on their path to the sea to breed.

    Photo Credit: James D. Morgan

    A local child in Flying Fish Cove watches in his block of flats as another crab goes past.

    Photo Credit: James D. Morgan

    Female red crabs wait to spawn on rocks at Flying Fish Cove on Christmas Island. When the time is right, just before dawn at high tide, the egg-laden females descend to the waterline to release their eggs, a process that can occur over several nights.

    Photo Credit: James D. Morgan

    Female red carbs crawl along the shore line at Ethel Beach. When the time is right, just before dawn at high tide, the egg-laden females descend to the waterline to release their eggs, a process that can occur over several nights.

    Photo Credit: James D. Morgan

    Even at the Christmas Island golf course, crabs find their way into the holes. The mass migration usually occurs around the wet season from October to January, and breeding is typically a synchonised event. The migration is also linked to phases of the moon to capitalise on releasing eggs on the high tide of the last quarter of the moon.

    Photo Credit: James D. Morgan

Gallery: Christmas Island red crab migration

By AG STAFF | June 18, 2014

Each year, up to about 120 million red crabs (Gecarcoidea natalis) scuttle to the sea from the forest across Christmas Island in an effort to mate. It is a commute which overwhelms the island – the 135sq.km Australian-owned island, located in the Indian Ocean 2600km northwest of Perth, has just over 2000 human inhabitants.