21. When the Doctor is observing how evolution has perfected survival skills, what creature does he consider having "perfect defence"?
From Quiz Listen
Answer:
Pufferfish
By himself in the TARDIS, the Doctor wonders why "we talk out loud when we know we're alone". He mentions that evolution has perfected survival skills, writing these on a blackboard. We see him in a tree, looking at a lioness take down a wildebeest as an example of a perfect hunter. He is then at the bottom of the ocean, looking out from the TARDIS at a pufferfish, deeming that to be something that exhibits perfect defence. The Doctor then asks, "Why is there no such thing as perfect hiding?" If such a creature existed, perfectly created by evolution to remain hidden, there would be no way of knowing if it actually existed. Putting down his piece of chalk, he then wonders what would happen if, suddenly, you "chose to speak aloud". "What would such a creature want? What would it do?" he asks. He turns round to pick up the chalk again, and it is not where he left it. Instead, it rolls toward him on the floor before he notices that "LISTEN" has been written on the blackboard.