A certain note on the wrestling behavior of Haemadipsa picta leeches: supplementary material

<p>Some terrestrial leeches mate by entwining the anterior ends of their bodies and then copulating. Here, we report first observations of a similar behavioral pattern in <i>Haemadipsa picta</i> terrestrial leeches from Malaysian Borneo. However, because the observed pattern can be easily induced artificially with no clear evidence of copulation, we suggest that it may serve another function, particularly in <i>H. picta</i>. We hypothesize that the wrestling behavior, as we term it, may be a ritualized aggressive display driven by competition for ambush location. Haemadipsid fauna of the region is poorly studied, therefore our observations extend limited knowledge about these leeches and open interesting research avenues for the study of the wrestling behavior.</p>