1. Concord Field Station, Department of Organismic and Evolutionary Biology, Harvard University
2. Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, The Royal Veterinary College, London, UK
3. Department of Ecology and Evolutionary Biology, University of California, Irvine, CA, USA
4. Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland