Ingo Arndt / Christmas Island Red Crab (Gecarcoidea natalis) blurred view of vast number of individuals moving along their annual migration route, Christmas Island, Indian Ocean, Australian Territory

Ingo Arndt / Christmas Island Red Crabs (Gecarcoidea natalis) crossing closed road, during annual migration, Christmas Island, Indian Ocean, Australian Territory, November 2009.

Ingo Arndt / Christmas Island Red Crabs (Gecarcoidea natalis) crossing road in huge numbers during annual migration, Christmas Island, Indian Ocean, Australian Territory

Ingo Arndt / Christmas Island Red Crabs (Gecarcoidea natalis) arriving in huge numbers, at coast for spawning, Christmas Island, Indian Ocean, Australian Territory

Ingo Arndt / Christmas Island Red Crabs (Gecarcoidea natalis) gatthered together on beach the day before spawning, Christmas Island, Indian Ocean, Australian Territory

Ingo Arndt / Christmas Island Red Crabs (Gecarcoidea natalis) massing on coastal rocks, the morning after spawning, Christmas Island, Indian Ocean, Australian Territory

Ingo Arndt / Christmas Island Red Crabs (Gecarcoidea natalis) shortly before sunrise sitting on rock ready for spawning, Christmas Island, Indian Ocean, Australian Territory

Juergen Freund / Thousands of Christmas Island Red crabs on rocky shore (Gecarcoidea natalis)

Juergen Freund / Christmas Island red crab (Gecarcoidea natalis) wearing Father Christmas hat, Christmas Island, Indian Ocean

Juergen Freund / Christmas Island red crabs (Gecarcidea natalis)Indian Ocean

Juergen Freund / Christmas Island red crabs mating {Gecarcoidea natalis} Indian Ocean, Australia

Juergen Freund / Masses of Christmas Island Red Crabs spawning on the beach.