Red Crab Mothers

Red Crab Mothers

Video. A female red crab lays up to 100,000 eggs and scatters them into the ocean when the tide is calm, sometimes drowning from the effort in the hopes that some of her offspring will survive to adulthood.

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.

This video documents the second stage of the red crab migration, after the crabs have mated and before the eggs hatch in the ocean. At the start of this stage, females brood their eggs in dirt or coastal rock burrows for 12 to 13 days. A female red crab can lay up to 100,000 eggs, which she holds in her abdominal sac. With the arrival of the waning moon, females make their way into the sea. In what looks like a dance, females brace themselves at the waters edge, and release their eggs.

Media Credits

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

September 27, 2022

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