Every year, Christmas Island, located in the Indian Ocean near the Indonesian Island of Java, becomes a striking sight as tens of millions of red crabs make their annual migration to the ocean. During this time, locals use leaf blowers and garden rakes to help the crabs on their journey. Approximately 50 million crabs travel from their homes to the beaches each summer to lay their eggs, creating a stunning red landscape across the Island.
Crabs: One of the largest animal migrators
One of the largest animal migrators on the blue planet, red crabs are making their way to the ocean. Every year, with the first monsoon rains in the Southern Hemisphere, tens of millions of red crabs begin their long journey to the ocean to mate and lay their eggs. The journey is especially long and dangerous for the small crabs, as they scuttle over rocks, through the forest, and across roads. On Christmas Island, traffic is stopped, and special bridges and tunnels are built to help protect the crabs during their migration. The crabs cover the landscapes in a huge red carpet as they travel from the forest to the sea.
Red Crabs | X
The reason behind the red crab migration
Red crabs travel to the sea to breed and to seek a partner. During reproduction, females must be close to the ocean to release their eggs into the water at high tide. The larvae emerge immediately and remain in the ocean before returning to shore as young ones. The migration is initiated by the early seasonal rains, which prevent dehydration, and is aligned with the lunar cycle to ensure that high tides provide optimal conditions for egg release.
Interesting facts about red crabs
Red crabs are omnivores that eat fallen leaves, fruits, and other dead crabs.
They play an important role in the rainforest ecosystem by helping to turn and fertilise the soil.
For most of the year, they spend most of the year in solitary burrows, which they defend from other crabs.
They are vulnerable to dehydration and need to remain close to water sources to access their gills, which is why they hide in burrows during the dry period.
Red crabs reach sexual maturity around 4–5 years of age and begin their annual migration at this point.
After males and females encounter each other and reproduce by the coast, the males head back to the forest, while females discharge their eggs into the ocean during the moon's last quarter.
