1. Theoretical and Applied Mechanics Program Northwestern University Evanston IL 60208 USA
2. Department of Mechanical Engineering Northwestern University Evanston IL 60208 USA
3. Department of Engineering University of Cambridge Cambridge CB2 1PZ UK
4. Lyles School of Civil Engineering Purdue University West Lafayette IN 47907 USA
5. Division of Invertebrate Zoology American Museum of Natural History New York NY 10024 USA
6. Department of Mechanical and Aerospace Engineering Materials Science and Engineering Program University of California San Diego, La Jolla CA 92093 USA