When my sisters and I were little, we occasionally came across box turtles in the woods near our house. We would bring them home and put them in a box with some water and lettuce, watching to see what they would do (usually nothing). When our father came home he invariably made us take the turtle back to the woods, telling us that wild animals shouldn’t be kept as pets – and knowing that we didn’t have any idea how to care for a turtle.
Life in a Shell doesn’t include the natural-history details that would have helped my sisters and me keep box turtles as pets. Instead, Donald Jackson’s book follows his career researching turtle physiology. Because Jackson was a respiratory physiologist, most of the book deals with respiration and associated systems or processes.
The first question Jackson tackles is the puzzle of why aquatic turtles float, instead of always sinking to the bottoms of ponds. Fans of Boyle’s Law and cloacal “breathing” won’t want to miss this. The core of the book focuses on how turtles deal with long periods underwater (when they’re not floating), with particular attention to the effects of temperature, pH balance, and how turtles buffer the lactic acid produced during anaerobic metabolism. If you come to this book unaware of the connections between respiration, metabolism, and the pH of body fluids, the scales will fall from your eyes before the last page is turned. Other chapters review experiments on the metabolic rates of turtles during various activities and the connection between the structure of turtle hearts and the ability to shunt blood.
Jackson’s summaries of the research performed to answer basic questions about turtle physiology provide examples of scientific reasoning and often show how unexpected observations spark a series of experiments. For example, if you measure the concentration of oxygen in a submerged turtle’s blood you will see it drop over time. This makes perfect sense – the turtle is using up oxygen but isn’t breathing. If you continue to watch, the concentration of oxygen will occasionally rise before resuming its drop. This apparently anomalous event leads into a discussion of what we know about reptile hearts (and how we know it). This information might make an interesting supplement to the short blurbs about amphibian and reptile circulation in general biology textbooks.
Although the book is about turtles, Jackson takes the opportunity to incorporate other organisms (elephant seals, alligators, jackrabbits, and humans) and interesting background information (e.g., the connection between the curse of a water nymph and a rare respiratory disorder). Some of the most interesting parts of the book occur during these asides, as well as when he broadens the narrative from a straightforward summary of the experiments conducted to telling stories about turtles. An example is Jackson’s recounting of research he and others performed at Tortuguero Beach in Costa Rica. Jackson goes beyond the details of experiments on nesting metabolism to talk about temperature sex determination and hypotheses for why some green sea turtles nest on Ascension Island, but feed thousands of kilometers away off the coast of Brazil.
Although Life in a Shell is marketed to non-biologists, the occasional technical term and the complexity of some physiological explanations make the book unsuitable for many casual readers. And, in some places, the book left me with the sense that the author had a topic to write about (turtle physiology) but not much of a story to tell. However, for anyone interested in physiology or turtles, the book will provide the joy of an intimate knowledge of how organisms overcome the challenges of their environment. Teachers of anatomy and physiology may find material for questions that see if students can apply a principle to an unfamiliar situation. Throw in numerous examples of how scientists think about doing science, and Life in a Shell is a book that many readers of ABT will want to read.