Meeting Abstract

P1.3  Wednesday, Jan. 4  Comparison of Startle Response in Two Ambystomid Species TAYLOR, Z. J.*; MILLIKEN, G. W.; College of Charleston; College of Charleston zjtaylor@g.cofc.edu

The ability of sensory systems to detect disturbances in the surrounding environment and select an appropriate startle response determines an animal’s ability to avoid predation. During the aquatic stage, salamander larvae are particularly vulnerable due to their small size. We tracked developmental changes associated with the startle response in A. tigrinum and A. maculatum, across the larval lifespan from the early to the late aquatic stage. To evaluate the startle response, larvae were placed into cups on a tray and were subjected to a brief vibrotactile stimulus. Responses were recorded and responsiveness was evaluated using z-scores and described in terms of locomotion. We found that despite being partly sympatric and of a similar ecological niche, the two species have different predator avoidance strategies. In the legless early aquatic stage (10 days post hatching), A. tigrinum exhibited the startle response while A. maculatum remained immobile. Animals that exhibited a statistically significant response also showed significant locomotion of at least one full body length in distance. In the quadrupedal late aquatic stage (23 days post hatching), A. tigrinum continued to exhibit strong startle responses with locomotion while more A. maculatum showed responsiveness to the stimulus. The observed differences in respective escape responses are examples of species typical behaviors present early in development and remain throughout the later part of the aquatic stage although A. maculatum begin to show a startle response in the later aquatic stage. Species differences in startle response could be attributed to morphological, ecological and ontogenic differences. A. tigrinum is a larger, predatory animal while A. maculatum is a smaller prey animal that exhibits comparatively rapid development to the terrestrial stage. Supported by HHMI.