Animals have been protagonists in many popular-science books before this one, and rightly so.  Long before the mental quicksand of cat videos, diversity of animal external forms and behaviors could not fail to fascinate even the most casual observer.  And early humans who were merely casual observers of other animals left few offspring.  Part of the fascination of external forms and behaviors, besides reconciling conflicting demands of becoming or obtaining food, is how visible parts and behaviors of other animals differ from or resemble those of humans.  An equally engrossing range of contrasts and comparisons exists among animal guts but remains largely invisible outside specialized, jargon-stuffed, scientific journals and textbooks.  Casual external observation cannot reveal that snakes, tigers, cows, elephants, worms, insects and clams differ from one another dramatically in approaches to digestion, accounting for big parts of their outward forms and behaviors and playing major roles in their evolutionary pasts and futures.  It should come as no surprise that eating meat, leaves, floral nectar, blood, milk, wood, mud and sand use very different processing equipment and procedures from one another.  

This book explores relations between gut forms and functions in a range of animals that vary widely in both diets and evolutionary histories.  By design, coverage is broad, uneven and incomplete:  Broad strokes of guts and digestion paint a general background supporting pointillist details of a small selection of particular guts to provide an impressionistic perspective.  A major focus here is the relation between the kinds of foods eaten and the structures and functions of guts tasked with making them available for uptake by the gut’s owner.  Think of it as a disassembly line delivering parts and fuel.