Three Gray classics on the biomechanics of animal movement.

It is a rare scientific paper that, 70 years later, is still being used as a source of both figures for review papers and experimental data for current research. And yet many still turn to the figures and plates published in 1933 by James Gray to understand how animals propel themselves through water. Gray’s three papers on aquatic animal locomotion published in volume ten of the Journal of Experimental Biology in 1933 (Gray, 1933a–c) form the cornerstone of modern attempts to understand aquatic locomotion. These papers, made easily available again with this issue of the journal, ushered in the era of quantitative studies of animal movement that had its heritage in the work of Borelli, Muybridge, Pettigrew and Marey, and continues to the present day as the burgeoning field of animal locomotor mechanics (Alexander, 2003; Bels et al., 2003; Biewener, 2003).