Scaling of feeding biomechanics in the horn shark Heterodontus francisci: ontogenetic constraints on durophagy

摘要: Abstract Organismal performance changes over ontogeny as the musculoskeletal systems underlying animal behavior grow in relative size and shape. As is a determinant of feeding ecology, ontogenetic former can influence latter. The horn shark Heterodontus francisci consumes hard-shelled benthic invertebrates, which may be problematic for younger animals with lower capacities. Scaling biomechanics was investigated H. ( n =16, 19–59 cm standard length (SL)) to determine biomechanical basis allometric whether this capacity constrains hard-prey consumption ontogeny. Positive allometry anterior (8–163 N) posterior (15–382 N) theoretical bite force attributed positive cross-sectional area two jaw adducting muscles mechanical advantage at point (0.79–1.26). Mechanical biting scaled isometrically (0.52). Fracture forces purple sea urchins Strongylocentrotus purpuratus consumed by ranged from 24 430 N. Comparison these fracture suggests that unable consume hard prey early its life history, but majority S. time it reaches maximum size. Despite constraint, appears facilitate an earlier entry into durophagous niche than would isometric trajectory. gape significantly smaller capable being crushed force. Thus, high cannot fully utilized while consuming similar toughness , potential trophic primarily determined capacity.