Fig. 6. The range of visco-elastic properties of different axial skeletons subjected to sinusodial bending. The notochords of hagfish (N=4) have apparent material stiffnesses (or Young's modulus) E, greater than that of the notochord (N=1) of white sturgeon Acipenser transmontanus (Long, 1995), the intervertebral joints (N=6) of blue marlin Makaira nigricans (Long, 1992) and the intervertebral joints (N=3) of saddleback dolphin Delphinus delphis (Long et al., 1997). Flexural damping C is normalized per cross-sectional area A of the notochord or intervertebral joint (note units of momentum); the notochord of hagfish has a range of values overlapping the range for sturgeon and marlin. For each species, the range of mean values are given (black bars) from dynamic cantilevered bending tests conducted at physiologically relevant curvatures and driving frequencies. The ranges include regional variation, when measured.