A look at how dogs know when someone is sick; why octopuses have blue blood; which animal makes the most amazing nest; exploring whether elephants really never forget; how cicadas make so much noise.

In this episode we ask: how do furry koalas keep cool in the Australian sun? How do elephants communicate when they're miles apart? Are vultures immune to disease? What is the secret to a frog's amazing tongue? And how do spiders live so long?