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Publication - Dr Erica Morley

    Electric Fields Elicit Ballooning in Spiders


    Morley, E & Robert, D, 2018, ‘Electric Fields Elicit Ballooning in Spiders’. Current Biology, vol 28., pp. 2324-2330.e2


    When thinking of airborne organisms, spiders do not usually come to mind. However, these wingless arthropods have been found 4km up in the sky [1], dispersing hundreds of kilometres [2]. To disperse, spiders “balloon”, whereby they climb to the top of a prominence, let out silk, and float away. The prevailing view is that drag forces from light wind allow spiders to become airborne [3], yet ballooning mechanisms are not fully explained by current aerodynamic models [4,5]. The global atmospheric electric circuit and the resulting atmospheric potential gradient (APG) [6], provide an additional force that has been proposed to explain ballooning [7]. Here, we test the hypothesis that electric fields (e-fields) commensurate with the APG can be detected by spiders and are sufficient to stimulate ballooning. We find that the presence of a vertical e-field elicits ballooning behaviour and take-off in spiders. We also investigate the mechanical response of putative sensory receivers in response to both e-field and air-flow stimuli, showing that spider mechanosensory hairs are mechanically activated by weak electric fields (100Vm-1). Altogether, the evidence gathered reveals an electric driving force that is sufficient for ballooning. These results also suggest that the APG, as additional meteorological information, can reveal the auspicious time to engage in ballooning. We propose that atmospheric electricity adds key information to our understanding and predictive capability of the ecologically important mass migration patterns of arthropod fauna [8].

    Full details in the University publications repository