Fig. 4. Biochemical composition of vertebrae from seven species of elasmobranch. Letters above the box and whisker plot denote significant differences between species. (A) Water content (% WM) is significantly different among species (F_6,153=70.483; P<0.001). (B) Mineral content (% DM) varied significantly among species (F_6,63=27.836; P<0.001). (C) Proteoglycan (PG) content, expressed as percentage of dry mass (DM), varied among species (F_6,82=10.531; P<0.001). The highest PG content was 28% found in I. oxyrinchus and the lowest was only 12% found in Ce. granulosus. (D) There were significant differences in collagen content, expressed as percentage of dry mass, among species (F_6,85=4.054; P=0.001). Overall, the collagen content of the species examined ranged from 17% (T. californica) to 27% (S. zygaena).