Meeting Abstract
Many teleosts respond to a negative stimuli using an escape mechanism called a C-start. During this behavior, they curl the entire body laterally into a C-shape (stage 1) then, using stored elastic energy and muscular contractions, swing the tail across the midline and accelerate away from the stimulus (stage 2). In some individuals, the time it takes to complete the C-start is shorter and the resulting net displacement is greater, which will increase the likelihood of escaping potential predators. We predicted that the following aspects of vertebral column morphology influence C-start performance: (1) longer vertebral (neural and hemal) spines store more elastic energy when bent and (2) decreased vertebral spine angle (the angle between a given spine and the vertebral column) will increase the effective spine length, which will also enhance elastic energy storage. We hypothesized that longer spines and shallower spine angles are associated with improved timing of the C-start behavior (i.e., shorter stage 1 & 2 durations) and greater net displacement. To test this hypothesis, we analyzed the C-starts of multiple individuals of Gambusia affinis using high-speed cinematography, then cleared and double-stained each individual and measured vertebral spine lengths and angles with ImageJ. Our preliminary analysis suggests that there are no significant correlations between vertebral element morphology and C-start performance. In fact, several spines actually show a weak positive association between spine length and stage durations, which is the opposite of our initial prediction. Future studies analyzing additional G. affinis individuals and sister species will determine if a larger amount of variation in vertebral morphology is associated with observed variation in escape response performance.
