Meeting Abstract
Like other teleosts, young flatfishes produce escape responses by imparting momentum to the water using the lateral aspect of the body. After metamorphosis, however, older flatfishes dwell on the seafloor and must produce the escape movement while their lateral aspect is in contact with the substrate. How do benthic-based escape movements compare to those performed by fish in the water column? We used high-speed video to capture images of Parophrys vetulus performing escape responses from the benthos and compared these behaviors to midwater escape behaviors in larval flatfishes and other teleosts. Benthic-based escapes begin with an upward head movement, while the tail remains against the substrate. Flatfish then peel the anterior body off of the substrate, accelerating the body vertically (~90° to the substrate). Finally, the tail follows the path of the head, at which point the fish leaves the substrate and moves into the water column. The fish then forms a whole-body bend toward the substrate and glides to the bottom. The differences between midwater and benthic escapes are as follows. (1) Phase 1 of a midwater escape is characterized by a C-shaped bend on the side of the body contralateral to the negative stimulus; phase 1 of a benthic escape is characterized by a J-shaped bend ipsilateral to the negative stimulus. (2) Phase 2 of a midwater escape is characterized by a wave of bending along the ipsilateral posterior body, which creates a tail-beat; phase 2 of a benthic escape is characterized by the contralateral side of the fish bending toward the substrate. The unusual kinematic features of the benthic escape response suggest that benthic-based escapes may be driven by a modified motor pattern produced by the Mauthner neurons, or perhaps even by an entirely new motor pattern.
