Hyperiella dilatata

In addition to protecting the pteropod, pteroenone 37 can also serve invertebrates as an indirect chemical defense (Fig. 2). The amphipod Hyperiella dilatata gains protection by carrying the pteropod Clione antarctica on its back. That this carrying behavior provides efficient protection is clear, since in all cases... 

One amphipod that lives as plankton in the frigid antarctic is a creature called Hyperiella dilatata. This little creature is about 2 millimeters long and has the ill-fated distinction of being a favorite food for several common plankton-eating antarctic fishes. Unlike some of its relatives, Hyperiella has no spines or other physical features that might discourage predatory fish, nor does it possess any compounds suitable for chemical defense. 

The pteropod Clione antarctica, a pelagic mollusc, produces the polyketide pteroenone (Structure 7.69).53 Pteroenone is distasteful to sympatric fish.54 C. antarctica are subject to capture by the amphipod Hyperiella dilatata, which holds them in place on its dorsum and is similarly avoided by the same fish predators (see Section III.A, below). 

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