The strategies used by animals to find and defend their mates in the grasslands of Namibia, the Serengeti, and Australia.

The ocean is where life first began, and where it first experimented with the mating game. All the creatures living here face the same challenge: how to find a partner in the largest and least-populated habitat on earth.

Jungles are home to 80 percent of all species, but they cover just 2 percent of the planet. When animals in these crowded forests want to mate, the challenge is how to stand out from the crowd.

Freshwater is often the stage on which millions of animals gather to find a mate, and the cycle of freshwater is the trigger for spectacular mating rituals and fierce competition.