Glycogen concentration in A Glycogen concentration in A. opercularis muscle tissue of unstressed animals (group 0) and animals that underwent complete run 1 and run 2 (group 4). Glycogen concentration in A. opercularis muscle tissue of unstressed animals (group 0) and animals that underwent complete run 1 and run 2 (group 4). White bars: smaller individuals [A0, A4: N=8, 11; shell height 50.97±4.473 mm (mean ± s.d.)]; grey bars: bigger individuals (B0, B4; N=11, 15; shell height 69.30±2.611 mm). Bars with the same letter are significantly different from each other (Student's t-test, P<0.05). Eva E. R. Philipp et al. J Exp Biol 2008;211:2492-2501 © The Company of Biologists Limited 2008