Gluing the ‘unwettable’: soil-dwelling harvestmen use viscoelastic fluids for capturing springtails

Gluing can be a highly efficient mechanism of prey capture, as it should require less complex sensory–muscular feedback. Whereas it is well known in insects, this mechanism is much less studied in arachnids, except spiders. Soil-dwelling harvestmen (Opiliones, Nemastomatidae) bear drumstick-like glandular hairs (clavate setae) at their pedipalps, which were previously hypothesized to be sticky and used in prey capture. However, clear evidence for this was lacking to date. Using high-speed videography, we found that the harvestman Mitostoma chrysomelas was able to capture fast-moving springtails (Collembola) just by a slight touch of the pedipalp. Adhesion of single clavate setae increased p…