Red Crabs are Everywhere at Christmas Island, Australia
It's the season of the red crabs.
Have you seen how the red crabs migrate? Well, this might interest you. When Christmas is approaches, millions of red crabs migrate to mate into the shore at Christmas Island in Austria.
On the island, red crabs are endemic, and residents are doing their best annually to help these crabs to migrate safely, especially as they cross the road. Most residents stay at home as the crabs block roads. But, sometimes, due to emergency circumstances, some of them are killed.
The migration takes up to a few days, as all adult male and female crabs must reproduce. Their journey usually begins in October to November or in wet seasons. At other times, they migrate later, which starts from December to January. As these crabs are prone to road kills, the residents and the government on the island made alternative changes.
Some of the residents use rakes to scratch the crabs away when people and vehicles pass by. There are also protection wheels attachments used to put the crabs on each side. On the other hand, the government also built crab bridges in the busiest places to help them cross the road using temporary barriers to lead the crabs into the crab bridge. There are also road closures in several areas.
Why Red Crabs Migrate?
Millions of crabs move to reproduce. The journey is led by the male crabs, leaving off crab burrows for the females to follow. They will arrive first at the shore. Then, they dip into the waters and dig a crab burrow. The male and the female start to mate at the burrow.
After the mating process, the male goes back to the land while the female stays under for two weeks. A female red crab carries at least 100,000 eggs in its brood pouch and spawns the seawater. After spawning, the female crabs will also go back to land.
The eggs will hatch as larvae into the water. Unfortunately, not all youngsters will be able to go through the process as many larvae might die. Manta rays and other marine species may kill or eat them.
Larvae that survive in this stage will likely develop into a megalopa in a month and turn into young crabs. They will also crawl out to the land just like the adults, which is also another migration. As these young crabs are tinier, resident uses leaf blowers to keep them away from the incoming vehicles.