Air and water

"Fish, shrimp, whales, and kelps live in the sea," writes Mark Denny, "and no one would mistake them for something that lives on land. By the same token, redwoods, hummingbirds, giraffes, and dragonflies are easily identified as being terrestrial." Denny's lively and informative book expands on this observation. Addressing general readers as well as biologists, he shows how the physics of fluids (in this case, air and water) influences the often fantastic ways in which life forms adapt themselves to their terrestrial or aquatic "media.". The book begins with a brief, accessible review of the basic concepts of physics and then applies these tools to describe the properties of air and water, among them being density, viscosity, electrical resistivity, and diffusivity. In each case the property under discussion is examined in a biological context: Why can sperm whales act like hot air balloons when terrestrial animals cannot? Why are trees taller than kelps? How do whirligig beetles use ripples as a form of sonar, and why can't mosquitoes detect the electrical activity of their prey as sharks can? Readers of Air and Water will be well rewarded by thinking about these and other questions in the context of physics.