Red carbs swarm Christmas Island every year as part of the migration process at the beginning of the rainy season, it's known as one of the top ten "most spectacular migrations."

A study back in 2010 sleds the long mystery surrounding the red crabs migrating all over the area known as Christmas Island. The number is estimated around to be 120 million of them that is massive it can be seen from the air turning the beaches to look like giant red spots.

Study co-author Lucy Turner stated normally sedentary species has the stamina to "undergo one of the most arduous migrations on earth."

The migration occurs generally in the beginning of the rainy season, which is anywhere from November to January, generally lasting for several days. The crabs end up in high rain forest plateau areas and then all the way down to Indian Ocean beaches where they mate in burrows. This year the crabs were expected to begin their migration in January.

"It's an amazing feat-going from not being able to exercise for more than ten minutes to walking for several miles," said Turner, a biologist at the University of Bristol in the United Kingdom.

"They descend cliffs, climb banks and maneuver around obstacles to reach the shoreline and lay their eggs, eventually returning to the island's central plateau with their offspring in tow," a CNN report described, listing the event as "One of the Most Spectacular Migrations" in a recent March report.

An expedition to witness the red crab migration can cost upwards of $1,500.