STANDEN, E.M.; LEVINE, R.P.; DOMENICI, P.; Harvard University; University of Massachusetts Amherst; CNR-IAMC c/o International Marine Centre: Fast and slow escape manoeuvres in the spiny dogfish (Squalus acanthias)

Little is known about the fast-start behavior of escape response in chondrichthyans. The aims of this study are to examine the escape response in the spiny dogfish and compare the kinematics and performance of these animals with those of previously studied teleosts. High-speed video was used to record the locomotor performance of spiny dogfish during escape-responses. Two distinct types of escape maneuvers were seen in the dogfish. These responses were classified as fast and slow based on the rate of turning of the anterior part of the body (head to center of mass). Fast responses (i.e. with high turning rates, >700 degrees/s) showed significantly higher locomotor performance than slow responses (i.e. with low turning rates, <600 degrees/s) in terms of distance covered, velocity and acceleration, although no differences were found in the turning radius of the center of mass during the escape maneuvers. The existence of two distinct types of escape responses has implications in terms both of neural control and muscular activation patterns. When compared to literature data for the locomotor performance of bony fishes, dogfish showed relatively low velocity and acceleration, while their turning radius was tighter than that of most teleosts, indicating high maneuverability. The locomotor performance observed in dogfish is consistent with their morphological characteristics: low locomotor performance associated with low thrust developed by their relatively small posterior depth of section, and high maneuverability associated with their high flexibility. In addition to traditional locomotor performance dogfish appear to have active use of pectoral fins during turning which may contribute to the maneuverability of the dogfish during fast-start behaviors.