SWANSON, BO; GIBB, AC; LANDELS, C; Northern Arizona University; Northern Arizona University; Northern Arizona University: Kinematics of aquatic and terrestrial escape responses in mudskippers: Does the same morphology produce a similar behavior across different environments?

Escape responses in fishes are rapid, often reflexive, behaviors that are critical for avoiding predators. Amphibious fishes are unusual in that they must perform escape responses in the water and on land. The barred mudskipper (Periophthalmus argentilineatus) serves as an excellent model system for the study of aquatic and terrestrial escape responses. We tested the hypothesis that aquatic and terrestrial escape responses are kinematically equivalent by examining mudskipper escape behaviors on land and in the water. High-speed digital imaging was used to record escapes, and the digital images were used to calculate intervertebral bending, velocities and relative timing of escape movements. We found that terrestrial escape responses were kinematically distinct from aquatic escape responses, with the former producing greater axial bending. Escape response stages were also relatively slower in the terrestrial environment. Thus, in terrestrial escapes fish produce more bending over a longer time period. This disparity could be due to differential muscle recruitment, or to different constraints imposed by the two environments. However, we found that maximum acceleration and velocity were not different between aquatic and terrestrial escapes. We suggest that mudskippers employ different motor patterns to produce distinct behaviors in each environment.