Meeting Abstract
The fins of fishes are innervated with sensory nerves and specialized endings capable of providing proprioceptive and tactile feedback. Across ray-finned fish studied, the sensory nerves extend distally within each ray following fin ray branching patterns. Nerve fibers exit the rays to innervate the inter-ray membrane, synapsing with mechanoreceptors. Mechanoreceptors respond to deformation of the fin and as the key link to the environment their location, number, and distribution may reflect adaptations to a particular habitat or fin function. To explore this further, we examined mechanoreceptor distributions in round goby (Neogobius melanostomus) pectoral fins, which frequently interact with the bottom substrate. Immunolabeling revealed a non-homogenous distribution of mechanoreceptors across the fin with fin rays located closest to the substrate exhibiting the highest concentrations. We found the highest density of endings within a ray in locations of fin ray branching. As these fin regions spread and deform during contact we suggest fin ray branching points may be particularly informative locations from which to sense contact and changes in fin ray position. These results lead to many questions regarding sensor placement, redundancy of the sensory system, and function of fin ray branching patterns. In an effort to tackle these questions, we compare our data in round goby to that of other species that vary in their frequency of substrate contact, pectoral fin function, and morphology and develop phylogenetically framed analyses in order to better elucidate the structure-function relationship of fin ray sensation.
