I admit, I bought this book because I had some credit at Harvard University Press and this had a great cover. Plus, I like turtles. What I did not know is how interesting turtles are from a physiological perspective. They can go without air for months. Months! They also have a funny way of breathing because they don’t have a conventional ribcage. And they make use of nutrients stored in their shells during the long hibernating period that they have. And their hearts work in a weird way and they have metabolism that’s all over the map from one speed to 10000x that speed (in contrast, the human metabolism ranges from about one speed to 4x that speed). Jackson looks into many of this interesting facts and describes the research that allowed him to discover or support these assertions. It’s a short well-written book for people who enjoy biological sciences.