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Glimpses of Creatures in Their Physical Worlds

Glimpses of Creatures in Their Physical Worlds

Steven Vogel
Copyright Date: 2009
Pages: 328
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  • Book Info
    Glimpses of Creatures in Their Physical Worlds
    Book Description:

    Glimpses of Creatures in Their Physical Worldsoffers an eye-opening look into how the characteristics of the physical world drive the designs of animals and plants. These characteristics impose limits but also create remarkable and subtle opportunities for the functional biology of organisms. In particular, Steven Vogel examines the size and scale, and trade-offs among different physical processes. He pays attention to how the forms and activities of animals and plants reflect the materials available to nature, and he explores the unique constraints and possibilities provided by fluid flow, structural design, and environmental forces.

    Each chapter of the book investigates a facet of the physical world, including the drag on small projectiles; the importance of diffusion and convection; the size-dependence of acceleration; the storage, conduction, and dissipation of heat; the relationship among pressure, flow, and choice in biological pumps; and how elongate structures tune their relative twistiness and bendiness. Vogel considers design-determining factors all too commonly ignored, and builds a bridge between the world described by physics books and the reality experienced by all creatures.Glimpses of Creatures in Their Physical Worldscontains a wealth of accessible information related to functional biology, and requires little more than a basic background in secondary-school science and mathematics.

    Drawing examples from creatures of land, air, and water, the book demonstrates the many uses of biological diversity and how physical forces impact biological organisms.

    eISBN: 978-1-4008-3386-3
    Subjects: Developmental & Cell Biology, Biological Sciences, Ecology & Evolutionary Biology

Table of Contents

  1. Front Matter
    (pp. i-iv)
  2. Table of Contents
    (pp. v-vi)
  3. Preface
    (pp. vii-xiv)
    Steven Vogel
  4. CHAPTER 1 Two Ways to Move Material
    (pp. 1-17)

    “No man is an island, entire of itself,” said the English poet John Donne. Nor is any other organism, cell, tissue, or organ. We’re open systems, continuously exchanging material with our surroundings as our parts do with their surroundings. In all of these exchanges, one physical process inevitably participates. In that process, diffusion, thermal agitation, and place-to-place concentration differences combine to produce net movements of molecules. On almost any biologically relevant scale, it can be described by exceedingly precise statistical statements, formulas that take advantage of the enormous numbers of individual entities moving around. Since it incurs no metabolic expenditure,...

  5. CHAPTER 2 The Bioballistics of Small Projectiles
    (pp. 18-38)

    Ours has long been a projectile-ridden culture, perhaps from our days of throwing rocks and hurling spears in efforts to damage potential edibles, predators, and competitors—the latter including conspecific ones. Long before inventing firearms, we made devices that improved the effectiveness of projectiles—atalatls, archery, catapults, and so forth. We rarely think of projectiles in any nonhuman context, but they turn out to be both common and diverse. Many animals jump; many plants shoot their seeds. While “many” may not imply “most,” terrestrial life is rich with examples of ballistic motion, motion in which a projectile gets all of...

  6. CHAPTER 3 Getting Up to Speed
    (pp. 39-57)

    Generalizations in biology come hard, so we treasure any that cut through life’s overwhelming diversity. In his famous essay, “On Being the Right Size,” J.B.S. Haldane (1926) notes that jumping animals of whatever size should reach the same maximum height, an insight he attributes to Galileo. Other iconic figures make the same assertion about the size-independence of height—Giovanni Alphonso Borelli (1680), grandfather of biomechanics; D’Arcy Thompson (1942), godfather of biomechanics; and then A. V. Hill (1938), father-figure for muscle physiologists.

    The basic reasoning is straightforward, at least if drag can be ignored. The force of a muscle varies with...

  7. CHAPTER 4 Moving Heat Around
    (pp. 58-79)

    We care about temperature. All too often we feel either too hot or too cold. Our appliances come with thermostats, cooling fans, and thermal protection switches. We determine the temperatures of organisms with thermocouples, thermal imaging equipment, and all manner of other thermometers. Temperature anomalies signal trouble, from personal fevers to global climate change. But the diverse and complex physical phenomena underlying temperature pose perilous pitfalls when it comes to explaining our data. Furthermore, we’re easily misled by the intuitive sense that grows out of the experience of a large, terrestrial animal given to maintaining a steady body temperature close...

  8. CHAPTER 5 Maintaining Temperature
    (pp. 80-94)

    Little else around us varies as much as the thermal loads that we terrestrial organisms face. Too often we’re too hot, too cold, too well illuminated by sunlight, too exposed to an open sky, or in too great contact with hot or cold solid or liquid substrata. Beyond that, both soil and water temperatures may be far from constant. Thermal loads vary in time scale as well as in magnitude. Air temperatures and radiative regimes change over every time scale relevant to their operation, from seconds to years, at the least. Variation may be as assured as (and because of)...

  9. CHAPTER 6 Gravity and Life in the Air
    (pp. 95-115)

    In our perceptual world, no physical agency imposes itself with greater immediacy than does gravity. We depend on it to walk or run; it injures us if we trip. It makes each of us about half a centimeter shorter at the end of each day than when we first arise. Our flesh sags as we age; more slowly, glaciers move downhill and rivers form deltas. We dream of escaping its constant crush, although our recent experiences in orbiting spacecraft reveal the difficulty of opting out of its perpetual pervasiveness. Physicists may regard the gravitational attraction between two objects as the...

  10. CHAPTER 7 Gravity and Life on the Ground
    (pp. 116-140)

    Unless actively counteracted, gravity inevitably makes aerial life descend. For terrestrial life, gravity’s roles are less obvious, less immediate, less consistent. Sometimes it matters; sometimes other agencies eclipse its effects. Sometimes it acts as impediment or nuisance; sometimes it plays a crucial positive role. While not exerting quite the same physical dominance, gravity has more diverse consequences and has elicited a wider range of biological devices for organisms that live out their lives on the ground.

    For one thing, much more depends on the distinction, made in the last chapter, between gravity, thus weight, and inertia, thus mass. Steadily lift...

  11. CHAPTER 8 Gravity and Life in Water
    (pp. 141-163)

    Life was born in water, and aqueous habitats still hold most of life’s diversity. The nearly aqueous density of most organisms ensures something close to suspension by the surrounding water. A creature might be twice as dense as the medium but never, as on land or in the air, a thousand times as dense. Gravity? We might expect only a minimal impact on design and deportment. But, as we’ll see, aquatic life’s similarity in density to its medium misleads us.

    As mentioned in the last chapter when considering the ascent of sap in trees, in aquatic systems gravity induces a...

  12. CHAPTER 9 Making and Maintaining Liquid Water
    (pp. 164-183)

    Metabolically active organisms contain water in its liquid phase—I know of no exceptions. Life’s domain consists of the places on the earth’s surface where liquid water will persist—or places where we artificially ensure that condition. No single phase of a single compound so characterizes the conditions necessary for life. Yes, a few organisms tolerate a few ice crystals, usually if extracellular. And water vapor plays useful roles—in reducing evaporation, as a condensable resource, perhaps for producing the density variations that permit free convection. But liquid water is crucial to life as we know it. In a once...

  13. CHAPTER 10 Pumping Fluids through Conduits
    (pp. 184-208)

    In the first chapter, I suggested that, because diffusion is ineffective over all but minute distances, an organism larger than a typical cell must move fluid to move material. By whatever name, internal bulk fluid movement absorbs energy as a consequence of that universal fluid property, viscosity. Supplying that energy requires some kind of pump. While the pump may also accelerate fluid or lift it against gravity, neither of these roles have quite the same inevitability. Not that the cost of pumping has to be metabolic. Sometimes an external agency can be coopted to do the work.

    The diversity of...

  14. CHAPTER 11 To Twist or Bend When Stressed
    (pp. 209-231)

    Several themes weave through the chapter that follows. While any—or all—might be left for a final encapsulation, perhaps they’re better borne in mind while reading it.

    For all its arcane and counterintuitive phenomena, fluid mechanics builds its bioportentous aspects on just a few material properties of gases and liquids—density, viscosity, and sometimes surface tension. And we’re mainly interested in just two substances, air and water. Solid mechanics, however great its intuitive familiarity, encompasses a daunting host of potentially significant material properties—three elastic moduli, three strengths, three maximum deformations, and three strain energy storages, corresponding to tensile,...

  15. CHAPTER 12 Keeping Up Upward and Down Downward
    (pp. 232-258)

    In defining an organism’s immediate physical situation, one begins with position and orientation. Position always matters, even if no exact specification need always be given for the pelagic or the aerial. And only in a few instances can orientation be ignored—for instance for non-motile spherical unicells in a continuous medium, perhaps a colonialVolvox(plate 1.1) in a pond, perhaps under some circumstances spherical eggs and nuts.

    We ordinarily treat orientation mechanisms as matters of coordination, topics in neurobiology. Detectors, in particular proprioceptors, provide information based on which nervous systems direct appropriate muscular activity. We’re less often concerned with...

  16. List of Symbols
    (pp. 259-262)
  17. References and Index of Citations
    (pp. 263-288)
  18. Index
    (pp. 289-302)