Red Crab Migration

Red Crab Migration

Video Gallery. Every day, millions of creatures are born into a life on the march, on the wing, on the run. They are migrants. Born to move.

Grades

6 - 12+

Subjects

Biology

Program
Great Migrations

Red crabs are native to Christmas Island, Australia. The central plateau of Christmas Island is dominated by strands of rain forest. The island has a tropical climate and experiences both a wet season (December through April) and a dry season (May through November).

More than 120 million red crabs can be found on the rain forest floor of Christmas Island. Red crabs live alone in dirt burrows, or deep rock crevices. Crabs stay in the shade of their dwelling for most of the year. In October or November, when the wet season is about to return, crabs begin their migration to the shore. This timing coincides with the lunar cycle and the tides.

Video 1: First, the male crabs meet the females on the shore. The males dig dens near the shore for the females to brood, or hatch, their eggs. Once they've mated, the males return to the forest and the females retreat to their dens.

Video 2: After 12 or 13 days of brooding their eggs, and with the arrival of the waning moon, female red crabs make a journey to the sea. Females reach the shore and release their eggs in the water. The waning moon plays a critical role in this stage of migration. The angle of the moon creates a neap tide, resulting in tides that are milder than usual. This gives the offspring a greater chance of survival.

Video 3: When released, the eggs hatch almost instantly, but the larvae remain in the water for one month, growing through several larval stages. Few are able to survive the harsh ocean currents and marine predators. Those that do survive begin the journey back into the rain forest, battling predators such as the yellow crazy ants along the way.

Media Credits

The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. The Rights Holder for media is the person or group credited.

Editor
National Geographic Society, National Geographic Society
Page Producer
Makayla Trotter,
Producer
Nina Page, National Geographic Society,
other
Last Updated

May 20, 2022

For information on user permissions, please read our Terms of Service. If you have questions about licensing content on this page, please contact ngimagecollection@natgeo.com for more information and to obtain a license. If you have questions about how to cite anything on our website in your project or classroom presentation, please contact your teacher. She or he will best know the preferred format. When you reach out to him or her, you will need the page title, URL, and the date you accessed the resource.

Media

If a media asset is downloadable, a download button appears in the corner of the media viewer. If no button appears, you cannot download or save the media.

Text

Text on this page is printable and can be used according to our Terms of Service.

Interactives

Any interactives on this page can only be played while you are visiting our website. You cannot download interactives.

Related Resources