The Christmas Island red crab ("Gecarcoidea Natalis") is a species of land crab endemic to the rain forest of Christmas Island and Cocos (Keeling) Island in the Indian Ocean and found nowhere else in the world.

The Territory of Christmas Island is an Australian external territory comprising the island of the same name. It is located in the Indian Ocean, 350 kilometres (220 mi) south of Java and Sumatra and 1,550 kilometres (960 mi) north-west of the closest point on the Australian mainland with an area of 135 square kilometres (52 sq mi). The Territory of Cocos (Keeling) Islands, is also a territory of Australia. Both islands are in the Indian Ocean, about one-half of the way from Australia to Sri Lanka.

Usually in October or November, but can sometimes be as late as December or January, red crabs all over the island leave their homes at the same time and start marching towards the ocean to mate and spawn. Female crabs produce eggs within three days of mating and will remain in the burrows for about another two weeks as the eggs develop. Each female can produce up to 100,000 eggs, which she holds in a brood pouch. When the moon reaches its last quarter, the egg-laden crabs leave their burrows and amass on the shoreline, packing into shady spots above the waterline. Spawning may occur on 5–6 consecutive nights during the migration. Red crab larvae hatch from the eggs as soon as they contact the water, although the majority does not survive marine and air predators.

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