Differences between the quality of diets and the metabolic costs of living in cetaceans.

<p>Means ± s.d. with different letters (a, b, c) show significantly different groups of cetaceans. A: Mean energy density of the diets (kJ⋅g⁻¹ wet mass). B: Cost of living as measured by the mitochondrial density of the muscle. C: Cost of living as measured by the lipid content of the muscle (% dry mass). Colours reflect the group of similarity identified for the mean energy density of diets: Group a in red, Group b in green and Group c in blue.