Christmas Island red crabs
One of the most incredible migrations is the seasonal movement of the red crab across Australia's Christmas Island.
More than 120 million red crabs call this remote island home, and every year they transform the island into a vast moving red carpet as they move en masse to the ocean to lay their eggs.
During periods of peak migration, Christmas Island's roads often must be closed as the crabs blanket the landscape. Scientists have recently discovered that hormonal changes cue the crabs to undertake their arduous journey.