Meeting Abstract

27.5  Monday, Jan. 4  Lateral bending kinematics of the vertebral column in Morone saxatilis NOWROOZI, B.N.*; BRAINERD, E.L.; Brown University; Brown University bryan_nowroozi@brown.edu

During axial undulatory locomotion in fishes, the intervertebral joints provide the vertebral column with the flexibility needed for lateral bending. However, due to the location of the vertebral column deep in the body, it has been difficult to measure precise intervertebral joint kinematics in vivo. Most studies of vertebral column function during locomotion in fishes have focused on in vitro bending mechanics and on body curvature. These studies have suggested that both the bending stiffness of the intervertebral joints and the maximum curvature of the body increase towards the caudal region of the fish. The current study investigates whether this pattern of longitudinal variation in mechanics and body curvature will be evident in the kinematics of the intervertebral joints. We used x-ray motion analysis of the startle response to quantify the kinematics of adjacent vertebrae along the length of three individual of striped bass, Morone saxatilis. Based on the vertebral kinematics, we calculated the average angle of bending between each set of three vertebrae along the length of the individual. On average, the intervertebral joints located in the caudal region of the body bent to a greater degree than those in the precaudal region. Typically, the most anterior vertebrae bend to an average of 4.8°, followed by a decline in bending angle in the precaudal vertebrae to an average of 4°, after which, the maximum angle of bending increases steadily through the caudal region to an average of 5.8°. We conclude that longitudinal variation of maximum intervertebral joint angle does exist with angles increasing towards the caudal region of the fish.