The presence of a refuge affects escape responses in the Staghorn Sculpin

Abstract

The influence of a refuge on escape responses was observed on Staghorn sculpins (Leptocottus armatus; Girard, 1854). The refuge was offered in sequences to compose four treatments to test if fish showed different behavioral responses. The locomotor performance to mechanical stimulation was observed by the use of high speed video tracking. There was no significant difference in velocity and acceleration between each treatment, except when responses were sorted in short and long latencies. To eliminate the possibility that the stimulus did not induce an escape response, angular velocities in startled fish were compared with the turning rate in routine swimming. This study showed that the presence of a refuge had an impact on the fish trajectories in the treatment where fish were orientated towards the refuge. As it was only in the treatment mentioned above a difference in trajectory was found after stage 2,a final trajectory at point F was used. In treatments where fish had the refuge behind them or where the stimulus hit the water, analysis of trajectories at point F showed a tendency that fish changed direction after a fast start towards the refuge. This may show that mauthner neuron induced responses were only towards a refuge if it was visually mediated in advantageous positions.