Meeting Abstract

S1-2.1  Friday, Jan. 4  Escape responses in fishes DOMENICI, P; CNR- National Research Council, Oristano, Italy paolo.domenici@cnr.it

The escape response is a common anti-predator behaviour observed in most animal species. Fish escape responses have long been considered all-or-none, stereotypic responses. However, recent work has shown that the kinematics and timing of fish escape responses are quite diverse, both within and across species. The kinematics, spatial and temporal characteristics of fish escape responses may be affected by a number of factors. Among these, stimulus characteristics (direction, intensity, distance), schooling, and environmental factors (i.e. hypoxia, temperature) can play an important role in modulating escape responses. Here, I argue that the variability found in kinematics and timing of escape responses in fish and other animals does not necessarily form a continuum, but rather reveals multimodal patterns of distributions in many case studies. Escape latencies are not always minimized, possibly as a result of a graded system through which sub-maximal responses may be used when the threat is not maximal, or in extreme environmental conditions. Similarly, specific patterns of escape directions were found. While maximizing unpredictability would correspond to random directions of escape, work on various species shows that escape trajectories are not random, although they can be multimodal as found in many species. Theoretical work suggests that optimal trajectories for escape should span 90-180 degrees from the predator’s attack, depending on the ratio between the speeds of predators and prey. Experimental results are in line with this prediction. Temporal, directional and kinematic patterns of escape response will be discussed in terms of their potential physiological and functional bases and their evolutionary significance.