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Because planarians avoid concentrated solutions of homogenized conspecifics, it has been proposed that planarians contain alarm substances that are released during predation. Since alarm signals should act at low concentrations, we sought to determine whether concentrated solutions of homogenized worms act as noxious stimuli instead. Two concentrations of crushed (distressed) worm homogenate or a control solution were pipetted into one side of a water-filled petri dish. The position of a live flatworm, Dugesia tigrina, was determined every 10 s for 20 min, 10 min before adding the test solution and 10 min after. Each treatment group consisted of 12 worms. There was a trend was towards avoidance of full-strength worm homogenate but not the diluted solution (mixed 2-way ANOVA, P = 0.079 for the interaction). As true alarm signals are likely to be highly diluted, these findings suggest that planaria do not contain alarm signals. To fully distinguish between the alarm signal and noxious stimulus hypotheses, further experimentation with larger sample sizes and a third dilution should be performed. [Poster]


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  • Event location
    • Library Technology Center 3rd Floor Open Area

  • Event date
    • 29 March 2012

  • Date submitted

    18 July 2022

  • Additional information
    • Acknowledgements:

      Frank Corotto