Once a year land bound Christmas Island red crabs are called back to the sea to birth their young, encountering obstacles in the forest along the way.

To many animals in the wild finding a mate is blood sport, driving to make long journeys, let down their guard, and even fight each other to the death.

An army ant colony in the forests of Costa Rica stalks its prey. This super-organism of tiny individuals is as deadly as any beast on four legs.