Meeting Abstract
The axial skeleton of fishes plays an important role in developing thrust during undulatory swimming. A considerable number of studies have focused on the established role of axial stiffness in modulating undulatory dynamics, including propulsive wavelength. Few studies, however, have addressed whether axial skeletal stiffness varies across species with different swimming styles defined by a spectrum of propulsive wavelengths. In addition, recent work in our lab indicates that propulsive wavelength increases as it passes through the fish body. In this study, we set out to (1) evaluate whether vertebral stiffness varies between species of different swimming modes including classically defined anguilliform, subcarangiform, and carangiform locomotor styles; and (2) whether vertebral stiffness contributes to the lengthening of the propulsive wave by a rostrocaudal gradient of increased stiffness. To this end, we measured the compressive stiffness of vertebrae using custom-built material-testing units along the vertebral columns of six species of teleost fishes: American eel (Anguilla rostrate), brook char (Salvelinus fontinalis), Florida pompano (Trachinotus carolinus), yellow perch (Perca flavescens), Chain Pickerel (Esox niger), and lookdown (Selene vomer). We found that the stiffness of the vertebral column increases rostrocaudally in all species and that overall vertebral stiffness is lowest is anguilliform swimmers and highest in carangiform swimmers. Taken together, these results indicate the importance of passive tissues in modulating swimming dynamics in fishes.
