Head to America's far north for its waterway's fighters, as a spring thaw pits eagles against herons and dragonfly nymphs against venomous water bugs.

Young gladiators earn their stripes in dense tropical forests. Stand back as a poison dart frog launches a toxic barrage and observe an epic turf war.

The secrets and ingenious tactics of Australia's toughest fighters, from a kangaroo's deadly boxing moves to the redback spider's precision-engineered trap

As the dry season brings gladiators to an African savannah watering hole, see a territory brawl and one honey badger's risky dance with a snake.