Complex structured environments offer fish advantages as places of refuge and areas of greater potential prey densities, but maneuvering through these environments is a navigational challenge. To successfully navigate complex habitats, fish must have sensory input relaying information about the proximity and size of obstacles. We investigated the role of the pectoral fins as mechanosensors in bluegill sunfish swimming through obstacle courses under different sensory deprivation and flow speed conditions. Sensory deprivation was accomplished by filming in the dark to remove visual input and/or temporarily blocking lateral line input via immersion in cobalt chloride. Fish used their pectoral fins to touch obstacles as they swam slowly past them under all conditions. Loss of visual and/or lateral line sensory input resulted in an increased number of fin taps and shorter tap durations while traversing the course. Propulsive pectoral fin strokes were made in open areas between obstacle posts and fish did not use the pectoral fins to push off or change heading. Bending of the flexible pectoral fin rays may initiate an afferent sensory input, which could be an important part of the proprioceptive feedback system needed to navigate complex environments. This behavioral evidence suggests that it is possible for unspecialized pectoral fins to act in both a sensory and a propulsive capacity.
B.E.F. and G.V.L. conceived and designed the study; B.E.F. executed the study, interpreted the results and drafted the article; and B.E.F. and G.V.L. revised the article.
Supplementary material available online at http://jeb.biologists.org/cgi/content/full/216/16/3084/DC1
No competing interests declared.
Funding was provided by the Office of Naval Research (grant N00014-09-1-0352 monitored by Dr Thomas McKenna).
- © 2013. Published by The Company of Biologists Ltd