Principles of Animal Locomotion

R. McNeill Alexander is Emeritus Professor of Zoology at the University of Leeds and a Fellow of the Royal Society. He is the author of more than a dozen books, including "Optima for Animals" (Princeton), as well as the award-winning CD-ROM "How Animals Move".

• PREFACE ix Chapter 1: The Best Way to Travel 1 1.1. Fitness 1 1.2. Speed 2 1.3. Acceleration and Maneuverability 2 1.4. Endurance 4 1.5. Economy of Energy 7 1.6. Stability 8 1.7. Compromises 9 1.8. Constraints 9 1.9. Optimization Theory 10 1.10. Gaits 12 Chapter 2: Muscle, the Motor 15 2.1. How Muscles Exert Force 15 2.2. Shortening and Lengthening Muscle 22 2.3. Power Output of Muscles 26 2.4. Pennation Patterns and Moment Arms 28 2.5. Power Consumption 31 2.6. Some Other Types of Muscle 34 Chapter 3: Energy Requirements for Locomotion 38 3.1. Kinetic Energy 38 3.2. Gravitational Potential Energy 39 3.3. Elastic Strain Energy 40 3.4. Work That Does Not Increase the Body's Mechanical Energy 42 3.5. Work Requirements 46 3.6. Oscillatory Movements 48 Chapter 4: Consequences of Size Differences 53 4.1. Geometric Similarity, Allometry, and the Pace of Life 53 4.2. Dynamic Similarity 58 4.3. Elastic Similarity and Stress Similarity 60 Chapter 5: Methods for the Study of Locomotion 68 5.1. Cinematography and Video Recording 68 5.2. Stationary Locomotion 70 5.3. Measurement of Energy Consumption 73 5.4. Observing Flow 74 5.5. Forces and Pressures 76 5.6. Recording Muscle Action 80 5.7. Recording Movement at a Distance 83 5.8. Properties of Materials 84 Chapter 6: Alternative Techniques for Locomotion on Land 86 6.1. Two-Anchor Crawling 86 6.2. Crawling by Peristalsis 88 6.3. Serpentine Crawling 90 6.4. Froglike Hopping 91 6.5. An Inelastic Kangaroo 93 6.6. A Minimal Model of Walking 95 6.7. The Synthetic Wheel 97 6.8. Walkers with Heavy Legs 98 6.9. Spring-Mass Models of Running 99 6.10. Comparisons 100 Chapter 7: Walking, Running, and Hopping 103 7.1. Speed 103 7.2. Gaits 109 7.3. Forces and Energy 114 7.4. Energy-Saving Springs 122 7.5. Internal Kinetic Energy 125 7.6. Metabolic Cost of Transport 128 7.7. Prediction of Optimal Gaits 133 7.8. Soft Ground, Hills, and Loads 136 7.9. Stability 139 7.10. Maneuverability 143 Chapter 8: Climbing and Jumping 146 8.1. Standing Jumps 146 8.2. Leg Design and Jumping Technique 150 8.3. Size and Jumping 153 8.4. Jumping from Branches 155 8.5. Climbing Vertical Surfaces and Walking on the Ceiling 159 Chapter 9: Crawling and Burrowing 166 9.1. Worms 166 9.2. Insect Larvae 170 9.3. Molluscs 171 9.4. Reptiles 176 9.5. Mammals 179 Chapter 10: Gliding and Soaring 181 10.1. Drag 181 10.2. Lift 183 10.3. Drag on Aerofoils 187 10.4. Gliding Performance 192 10.5. Stability 200 10.6. Soaring 201 Chapter 11: Hovering 209 11.1. Airflow around Hovering Animals 209 11.2. Lift Generation 213 11.3. Power for Hovering 221 Chapter 12: Powered Forward Flight 224 12.1. Aerodynamics of Flapping Flight 224 12.2. Power Requirements for Flight 228 12.3. Optimization of Flight 236 Chapter 13: Moving on the Surface of Water 240 13.1. Fisher Spiders 240 13.2. Basilisk Lizards 244 13.3. Surface Swimmers 246 Chapter 14: Swimming with Oars and Hydrofoils 249 14.1. Froude Efficiency 249 14.2. Drag-Powered Swimming 250 14.3. Swimming Powered by Lift on Limbs or Paired Fins 255 14.4. Swimming with Hydrofoil Tails 261 14.5. Porpoising 264 Chapter 15: Swimming by Undulation 266 15.1. Undulating Fishes 266 15.2. Muscle Activity in Undulating Fishes 277 15.3. Fins, Tails, and Gaits 282 15.4. Undulating Worms 284 Chapter 16: Swimming by Jet Propulsion 288 16.1. Efficiency of Jet Propulsion 288 16.2. Elastic Mechanisms in Jet Propulsion 296 Chapter 17: Buoyancy 301 17.1. Buoyancy Organs 301 17.2. Swimming by Dense Animals 303 17.3. Energetics of Buoyancy 307 17.4. Buoyancy and Lifestyle 311 Chapter 18: Aids to Human Locomotion 316 18.1. Shoes 316 18.2. Bicycles 318 18.3. Scuba 321 18.4. Boats 322 18.5. Aircraft without Engines 324 Chapter 19: Epilogue 327 19.1. Metabolic Cost of Transport 327 19.2. Speeds 328 19.3. Gaits 330 19.4. Elastic Mechanisms 331 19.5. Priorities for Further Research 331 REFERENCES 333 INDEX 367

"A valuable reference book written by a leader in the field."--Stephen Gatesy, Nature "A remarkable volume that simply must be read by anyone contemplating any kind of work on, or in imitation of, muscle-driven motion. This is no ordinary summing up but rather a synthesis, an explication of principles--the title needs no disclaimer... [O]ne should read it in short bouts separated by intervals of contemplation."--Steven Vogel, American Scientist "This is an important work that will be appreciated by anyone interested in animal biomechanics... Alexander is gifted in his ability to choose or create models that are sufficiently simple as to be understandable and tractable, but not so simple that they stray far from biological reality."--Robert Josephson, The Quarterly Review of Biology "The book will be a godsend for any lecturer looking for a course book about animal locomotion, and many a naturalist will find that it sheds a flood of light on the reasons behind the endlessly surprising things that animals do... [A] 'must have' for anyone who thinks in terms of physics about the way animals work."--C. J. Pennycuick, Trends in Ecology and Evolution