The annual migration of millions of red crabs from the rainforests of Australia’s Christmas Island to the coast is still underway. After the first rain of the wet season, which occurred at the end of October this year, the red crabs of Christmas Island begin their march to the coast to mate and spawn. The crabs form a river of red as they cross roads, streams, sidewalks and even human feet to reach the sea. Videos shared by Instagram user @Norazian.ah show hundreds of crabs crawling over grassy, rocky and paved terrain on their way to the coast. The fearlessly crawl over a person’s feet, and across roads. The crabs always spawn at a very particular time: before dawn on a receding high tide during the last quarter of the moon, according to Parks Australia. Depending on when the first rain occurs, they may hurry on the trek to the coast or they may stop to take in the sights along the way. The larger male crabs generally arrive first and begin digging burrows. The female crabs join them to mate in and around the burrows, and the males then return to the forest. The females remain in the burrows and produce their eggs — up to 100,000 each — within three days of mating. When the moon is in its last quarter and tide starts to turn before dawn, the crabs release their eggs into the ocean. The crab larvae hatch as soon as they touch the water. They grow for about a month and gather in small pools near the shore, and when they measure about 5 mm across, the tiny crabs start the journey inland. If they make it, they remain hidden in the forest for their first three years. According to Parks Australia, most of the baby crabs don’t survive. The large swarms of larvae provide an annual feast for fish, rays and whale sharks. “Once or twice a decade, a huge number will survive, which is enough to maintain the island’s large crab population,” the agency said.