Meeting Abstract
Most fishes perform a C-start (or fast-start escape response) in response to a negative stimulus. The C-start accelerates the center of mass away from the stimulus and is the primary mechanism for predator avoidance. We sought to determine the effect of temperature on development of the vertebrae and to ascertain if variation in vertebral number affects the C-start. To accomplish this we spawned roundtail chub (Gila robusta) and held individuals at 15°C, 20°C and 25°C through eight months of development. After this period, some individuals were cleared and stained to determine vertebrae number and the abdominal: posterior vertebrae ratio. With the remaining individuals we triggered a C-start behavior and recorded the response with high-speed videography. Performance variables were measured from these videos using ImageJ and Kinovea. Vertebral numbers did not differ between the three temperature treatments; however, the vertebral ratios did change with temperature. The 15°C-reared fish had a higher ratio of posterior to abdominal vertebrae, but 20°C- and 25°C-reared fish did not differ. During the C-starts, 15°C-reared fish had the highest body curvature, followed by the 20°C- and 25°C-reared fish. Variation in curvature did not translate to an increase in speed. The 20°C-reared fish reached the end of stage one (preparatory phase) in 0.041 seconds which was significantly faster than the 15°C- and 25°C- reared fish (0.049s and 0.045s respectively). Thus the 15°C-reared fish were the slowest during the C-start and displayed the highest curvature coefficient. 15°C-reared fish may be disproportionally long in the caudal region because they have more posterior vertebrae relative to the other fish. The extra vertebrae in the posterior region could allow them to be more flexible but decrease their speed entering and exiting the C-start.
