Hyperiid amphipod crustaceans are abundant in Southern Ocean waters from the Polar Frontal Zone to shelf waters where they represent a major prey for fish and seabirds. Hyperiella dilatata has evolved a peculiar anti-predatory behaviour: it abducts chemically-protected, shell-less pteropods from the water column and carries them on their dorsal side, holding it between its pereopods (McClintock & Janssen, 1990). The pteropod Clione antarctica produces de novo a predator-deterrent chemical named pteroenone (Bryan et al., 1995). Tandem pairs of pteropods and amphipods were significantly less predated upon than single individuals of Hyperiella and hence this behaviour is very efficient as protection from visually hunting icefish in the crystal-clear shelf waters around the continent (McClintock & Janssen, 1990), however, in the open ocean this behaviour was so far undocumented. We report this association at four different open-water sites in the Southern Ocean between 45 and 71°S and develop hypotheses on its origin and function. H. dilatata abducted Spongiobranchaea pteropods in the Polar Frontal Zone and Clione further south in the Weddell Sea. Lengths of the abducted pteropods varied greatly; the biggest pteropod carried was around half the host’s size. Molecular barcodes of both host and pteropods were obtained. Finally, we hypothesize against which potential predators this anti-predatory behaviour may have been selected for.