Carla is a red crab. She lives on Christmas Island. In November, when the rains come, Carla and her fellow crabs begin to march.

Christmas Island is an Australian territory. It is in the middle of the Indian Ocean. It has rain forests in the center. It has beaches on the coast.

Carla and her relatives move from the forest to the beach. It takes them two whole weeks. Their goal is to make it to the beach in time to mate during high tide of the new moon.

The crabs’ journey is not easy. They have to make it past the busy roads without getting squashed by the cars. They have to climb up and down steep cliffs.

Carla is very hot and thirsty. Many of her friends will die without enough water. Others will die because they are too tired to keep walking.

If the crabs overcome these obstacles, they might have to deal with yellow crazy ants. The yellow crazy ants spray formic acid. The acid can hurt the crabs. Carla is lucky to make it through the ant territory.

Sometimes there are fights with other crab species. Each type of crab wants to use the burrows in the sand on the beaches. Who will win?

Carla gets a burrow this year. She made it. But she wonders if she will make it again next year. Climate change is making rain more unpredictable. It is confusing the timing of the crab migration.

One day the rain may not come at all. Carla and her species would not migrate and they would not reproduce. How long could the crabs survive without new crabs each year? Carla hopes she won’t find out. But for now, she is safe.