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Evolutionary biologist, comedian, and aspiring Dr Frankenstein Simon Watt is on a quest to improve the human body, with a little help from our animal cousins. In each episode he turns his imaginary scalpel on a different human organ and wonders if we wouldn’t be better off with something slightly different – the eyes of a chameleon, for example, or the guts of a vulture!

For our final episode, we're wondering how to improve those squishy, spongey sacks of air that keep us pumped up with oxygen - our lungs. First up is Colleen Farmer from the University of Utah, expert in all things crocodilian. Both crocs, and their sister-group, birds, have a unique unidirectional flow system in their lungs, powered by air sacs that keep the air moving. It allows them to breathe - HARD - without damaging the fragile capillaries which keep our blood topped up with O2.

Breathing is one thing, but HOLDING your breath is another. Introducing the Cuvier's Beaked Whale, the champion cetacean breath-holder, with a record dive time of over three and a half hours. With specially designed cartilage that allows their lungs to squash completely flat, and myoglobin-packed muscles which can store an incredible amount of oxygen, everything is designed to keep them under for longer.

But perhaps lungs are over-rated after all. Surely there are other options out there? Why not ask a Painted Turtle - hibernating for months on end at the bottom of a frozen Canadian lake - their lungs are all but useless for half the year. Instead, they've developed an amazing breathing strategy. Forget talking out of your butt; these turtles breathe out of theirs! Suzie Simpson from the British Herpetological Society takes us through it.

A ´óÏó´«Ã½ Audio Bristol production for Radio 4, Produced by Emily Knight