Why more then 50 million red crabs migrate on Christmas Island

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Nearly 55 million red crabs, also known as Gecarcoidea Natalis, are estimated to be living on Christmas Island, located in the Indian Ocean off the northwestern coast of Australia. Between October and December, at the start of the wet season, red crabs start a fantastic journey across the island, leaving their homes to go to the seaside to lay their eggs.

When the migration takes place?

According to Australian government reports, female crabs drop their eggs into the water (this process is known as spawning) before sunrise on spring tides during the last quarter of the moon. The migration process starts when crabs are sure that they can complete the journey, mate, and then brood eggs too before spawning.

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The possible dates for spawning this year are during the Australian spring, i.e., 22-24 November and 21-23 December. Five to six weeks before these dates, crabs start their journey to the ocean across cliffs, forests, and roads.

The stages before the birth of new crabs

Once the crabs reach the seaside, they dip in the ocean to provide their body moisture and salts. Then male crabs dig holes in the sand where mating happens, and after that, the male crabs start their journey back to the island.

Female crabs remain inside the tunnels and brood eggs for nearly two weeks before dropping eggs into the water and returning to the island. In the ocean, the crab eggs hatch into larvae and soon evolve into baby crabs; their carapace is only five-millimeters long. They also immediately start their journey to their parent’s island to find a place to live. After 4-5 years, they will grow and become adults and are ready to mate.

People on Christmas Island try to protect crabs during this migration

People living on Christmas Island do everything possible they can to avoid accidentally killing crabs. They have built underground tunnels and bridges to allow crabs to cross streets safely. During the peak time of migration, the government closes some roads, and traffic is diverted away from where you can see a red carpet moving on the way.

About Christmas Island

The Territory of Christmas Island is an Australian external territory which is comprising of the island of the same name. The island is located in the Indian Ocean, around 220 miles south of Indonesia’s Sumatra and Java island, and about 990 miles north-west of Australia. The island has a total area of 52 square miles.

Interesting facts about Christmas Island crabs

  • At one point in time, there used to live, nearly 100 million adult crabs on Christmas Island Still, the accidental introduction of the Yellow Ant had killed almost 20-30 million red crabs in recent times.
  • Yellow crazy ants were introduced by humans back in 1915.

Final words

Today, Christmas Island crabs are essential for the island ecosystem, and the Australian government and island people are doing everything to save these species and let them create more species. Keeping the crabs from getting endangered.

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