They're also some of the only animals that can breathe with their butts. You see, inside a turtle shell is a very particular respiratory system. Wojakowski: You will see the lungs towards the top ...

Dr Fraser says "Turtles are very strange animals. They have a straightjacket of a shell. "If you can imagine yourself with your shoulders within your rib cage, you'd be pretty restricted." ...

Instead, hermit crabs have a hard exoskeleton on the front part of their bodies but a soft tail on the other half, which they protect using the discarded shells of other animals, like whelks.