Numerous species of fishes from multiple orders produce and recognize chemical alarm signals. In Ostariophysan fishes, the alarm substance originates in epidermal cells and is released when their skin is damaged. Recent publications have explored this mechanism and have proposed explanations for the evolution of a seemingly altruistic trait. Fathead minnows (Pimephales promelas) respond strongly to alarm pheromones released from conspecifics by increasing shoal coordination, seeking cover, decreasing foraging, and remaining motionless. Naive fathead minnows learn to recognize a novel predator’s scent from experienced fish. This case of visual and chemical communication of threat suggests that fish may be able to perceive a threat using visual cues alone. Fish that have not been reached by the dispersion of the alarm chemical may benefit by recognizing the reactions of other fish in the scent area and respond accordingly. We asked whether fathead minnows can perceive a threat by simply observing conspecifics who are exposed to the alarm substance. We exposed groups of fathead minnows to skin extract containing the alarm pheromone and observed the responses of fish in adjacent aquaria to determine whether this second group of fish perceived the threat that was presented to the adjacent fish.
Casey Michael Godwin, ’03 Libertyville, IL
Majors: Biology, Environmental Studies
Sponsor: S. Andrew McCollum