Red Crab Invasion and Monarch Magic: Reading Comprehension Assignment

Christmas Island is an Australian territory in the Indian Ocean. The island is actually a plateau at the top of a mountain that is mostly underwater. Only 1,500 or so people lived on the island as of 2010. But Christmas Island is a special place.

The island boasts an array of exotic plants and animals, some of which are found nowhere else in the world. Among this great diversity are more than 100 kinds of crabs. The red land crab makes up the largest population of the land crab species. These crabs spend most of their lives on land; however, once a year almost 120 million of them are driven by instinct to make a treacherous trip to the ocean. The crabs let nothing stand in their way, swarming in red waves over the streets and homes of the island.

The migration begins during the rainy season in October and November. The process can last as long as a few weeks, and the crabs can travel several miles to the ocean and back. They travel a nearly identical path year after year. During that journey they risk getting run over by cars, suffering dehydration, or being attacked by other animals. But the crabs will navigate over or around anything in their path.

The male red crabs are the first to begin the journey. They leave their burrows in the rain forest near the peak of the plateau and scurry toward the ocean. At the beginning of this migration, it appears as though the mountain is erupting with crabs. The crabs make their way down the side of the plateau and cross the path of the people living there. The roads become crab-crossing zones, with traffic halting frequently while the small crustaceans race toward the beach. Homes in the crabs’ path can become overrun with the little red creatures. And schools on the island experience the spectacle of thousands of crabs scuttling over walls and through hallways and classrooms as they try to reach their destination.

Soon after the males begin their descent, the female crabs join them. The females take a similar path to the ocean. Then the males and females mate near the water. After mating, the males return to higher ground, but the females wait by the shore to lay their eggs. After almost two weeks, the females make their way to the edge of the ocean, where they release their eggs. Each female red crab can produce up to 100,000 eggs. The female crabs then travel back to their burrows in the forest, leaving their eggs unprotected. This might be the most dangerous time in the breeding cycle for the species. Predators prowl the shoreline during this time, awaiting a tasty meal of crab eggs.

The baby crabs hatch in the ocean and live their first few weeks in the water. There they are vulnerable to fish and birds. Many do not survive, but those that do undergo a change as they leave the ocean. They shed the outer layer of their shells as part of a process called molting, which they do many times over the course of their lives. Then the tiny crabs travel to the forest where they will grow to adulthood and take part in the next migration.

The red crab migration forces people on the island to make some accommodations for the crustaceans. Roads are closed, and the routes of the crabs are reported on the radio. The annual migration has become a part of life for the locals. Also it is a way for the remote island to attract visitors. Many tourists travel to Christmas Island to witness the red crab migration, boosting the local economy. For visitors and residents alike, the sights and sounds of millions of crabs scrambling over land provide a fascinating experience.