Beaches Turn Red With Billions of Baby Crabs in 'Extremely Rare' Event

Billions of baby crabs have been filmed on the shores of Christmas Island in perhaps the largest event of its kind ever caught on camera.

"It's extremely rare that they ever even come [to the beach]," Toby Nowlan, a producer for the new Netflix docuseries Our Planet II, which showcases the event, told Newsweek. "It's incredibly hard to predict because they only turn up one year in ten. That's why we were so keen to film it."

On their first attempt, the crew was unsuccessful at capturing the mind-boggling migration. "The first year we pitched up and not a single crablet turned up on the beach," Nowlan said. "We only had two filming years so we had one more chance. When we went back the second year I was just biting my nails, hoping that the laws of probability were on our side.

"Amazingly, on Christmas Eve, we had this amazing present—suddenly the beaches were red with this tide of larval baby crablets just swarming. There were billions of them if not trillions. The beach was just covered. It was one of the biggest returns of baby crabs that has ever been recorded and quite possibly the biggest ever filmed."

Red crabs are native to Christmas Island, an Australian territory in the Indian Ocean, south of Java, Indonesia. According to National Geographic, more than 120 million red crabs live on the island, which is more than the population of the four largest states in the U.S. combined.

For most of the year, the crabs stay in the shade of the rainforest, living a solitary life in dirt burrows and rocky crevices. But, in October and November, the crabs move towards the shore to mate and lay their eggs, coordinating with the high tides and the waning moon.

Then, towards the end of December, the baby crabs return to the shore to make their journey back into the tropical forests.

Recording this event is difficult at the best of times, but the second round of filming was even more so when the camera crew was unable to travel amid global COVID lockdowns. As a result, Nowlan and his team had to direct the filming remotely, with the help of local crews and Whatsapp.

"In this series, we've done more remote shoots than ever before because of COVID, but it's something we do more and more now as we really need to justify when we're traveling on long-haul flights, especially for a documentary like this where we're publicizing the plight of these species."

The journey of the Christmas Island crablets is just one story featured in Netflix's nature docuseries, Our Planet II, narrated by David Attenborough. The series follows the migrations of different animals across our planet, under the overarching theme of "movement."

"Movement is just such a crucial part of the fabric of life," Nowlan said. "The health of our planet really depends on that freedom to move."

"We are suddenly making so many of those journeys really difficult. We are putting up hurdles, we're putting up barriers every time we put up a wall or a fence, and we put up blockades and nets in the ocean and in rivers and dams," he said. "These are all silent barriers to many really ancient migrations that have been happening for a lot longer than we can even imagine."

Our Planet II will be available to stream on Netflix from June 14.