and Peter Cain, Ph.D.

SLU Festival of Science 2001 Poster Presentation

 

This study examined the role of hydrostatic pressure in the navigation abilities of weakly electric elephantnose fish, Gnathonemus petersii, in familiar environments.  Fifteen subjects were placed at random into either the intact control, electrically silenced, or sham-operated control group.  The fish’s task was to locate and swim through an aperture in a Plexiglas wall dividing a 200-l aquarium into two equal compartments.  After the fish had become familiar with the aperture location over five consecutive trial days, the fish underwent the appropriate surgical procedures.  On the sixth day fish went through a final trial to account for any effects of the surgery.  The water pressure was then raised to simulate water that was 10 cm deeper than the actual height, and the fish were tested at the novel pressure.  The measures of fish performance included: (1) the amount of time it took the fish to locate and swim through the aperture, (2) the height of initial contact with the divider wall, (3) the height at which the fish crossed the electrolocation boundary, and (4) the number of crossings.  Analysis of variance and t-tests were performed to see if a difference existed between performance during the five trials and after the water pressure change.  Results indicate that the fishes’ orientation and navigation through the aperture was significantly effected by the hydrostatic pressure change.  This suggests that weakly electric fish do use hydrostatic pressure cues as a primary source of information for navigation in conjunction with other sensory input such as their electric organ discharge.