He’s an absolute legend- 
Here’s one quick story 
In nature - an animal under threat or startled would normally use the most efficient way to escape danger right ? He noticed that a trout disturbed in a mountain stream wound always swim upstream !! So he looked into it - turns out the gills don’t just filter water - the act of removing oxygen from the water through the gills causes the waste from the gills to attract Oxygen - so if you can imagine the shape of a fish - what better way to increase thrust buy using your shape and chemistry to push you ( a bit like soap in your hand ) so the faster the flow though the gills - equals faster thrust … you still with me ? 
So Gill waste has no oxygen, but it wants to join with oxygen so - oxygen rushed In and push’s the shape uphill - more intake = more thrust 🤯 genius