Fatty acid distributions in five taxonomic groups in Illinois, USA. Lines represent fatty acid profiles, and are not chromatograms. The distributions of fatty acids in Illinois river otters (tail: n = 46; footpad: n = 19), and 2 crayfish species (n = 14), 3 frog species (n = 12), 14 fish species (n = 56), and 5 mollusc species (n = 37). Each line indicates the mean value for all individuals of a given species. The y-axis is the percentage makeup by mass. All fatty acids were assigned to one of 60 possible groups. Those which we were able to identify from our standard are labeled as tics in each graph, and with their identity presented along the x-axis.