Figure 2

Kinematics and hydrodynamics around paddles of six morphologically and taxonomically diverse species. (c) and (g) are representative images showing the kinematic (c) and hydrodynamic (g) measurements of the ctenes of ctenophore Pleurobrachia brachei swimming up. The ctenes and limbs of the five species analyzed bent similarly during their power stroke, whereby, (a) the mean bending angle among all the species was 27° ± 6.1 (mean shown by solid line and s.t. dev. shown by dashed line) and (b) the mean inflexion point among all the species was located 0.59 ± 0.045 along the the limb/ctene. The (d) peak water flow (i.e., maximum flow velocity) was located near the inflexion point occurring on average at 0.68 ± 0.1 along the limb/ctene. In addition, (e) water flow was on average 1.31 ± 0.22 times greater on the leeward side of the limb/ctene than the flowward side (blue dashed line shows unity). The (f) average negative pressure along the length of the leeward side of the limb/ctene was 5.65 ± 3.3 times greater than the average positive pressure along the flowward side. Error bars represent the s.t. dev among replicated individuals of each species (n = 3). The white scale bar in (g) is 1 cm in length.