The world's biggest beasts have always captured people's imagination. But while being big can have its advantages, it also comes with sizeable challenges. From the Komodo dragon, whose huge appetite means it must take on prey 10 times its weight, to the giraffe, whose long neck must control immense blood pressure, nature's biggest beasts must go to extraordinary lengths to thrive. This film tells just some of these survival stories. Narrated by Miles Jupp.