Meeting Abstract
100.7 Sunday, Jan. 6 Fish fins function as dual sensory and motor neuromechanical systems. HALE, M. E.*; WILLIAMS IV, R. ; Univ. of Chicago; Univ. of Chicago mhale@uchicago.edu
The roles of fin movement in behaviors have been studied widely across the broad diversity of jawed fishes, both living and extinct. Fins serve diverse behavioral functions. They propel and brake, maneuver and stabilize, clasp, threaten and defend. In tetrapods, such behaviors require considerable feedback from mechanosensors in the limbs that provide proprioceptive information on limb position and movement. Without such input limb movements and the behaviors that include them are greatly impaired. We have found that fish fins used extensively in locomotion and for stability receive proprioceptive feedback from several types of sensory nerve fibers. Afferents run distally along the fin rays and into the fin membranes. With physiology on the pectoral fins of bluegill sunfish, a species that uses its pectoral fins extensively during swimming, we determined that these nerve fibers respond both to bending and to static position of the rays. Surveying several taxonomically distant species suggests that a proprioceptive response to fin ray bending is common. Transection of the pectoral fin ray nerves of bluegills alters fin use in locomotor behaviors, indicating that the sensory feedback these nerves provide is important for motor function. Together these data demonstrate that pectoral fins with significant roles in locomotion and other behaviors also need to be examined as potential sensory structures. Considering pectoral fins used in locomotion as dual sensory and motor systems has implications for studies of their morphology and movement, as changes in fin shape, size, stiffness and movement pattern could impact the sensory input received. We suggest that other fins likely use similar feedback and that mechanosensory function and sensorimotor integration should be considered in studies of fin functional morphology and evolution.
