| Summary: | The presence of supercooled water in polar regions causes anchor ice to grow on submerged objects, generating costly problems for engineered materials and life-endangering risks for benthic communities. The factors driving underwater ice accretion are poorly understood, and passive prevention mechanisms remain unknown. Here we report that the Antarctic scallop Adamussium colbecki appears to remain ice-free in shallow Antarctic marine environments where underwater ice growth is prevalent. In contrast, scallops colonized by bush sponges in the same microhabitat grow ice and are removed from the population. Characterization of the Antarctic scallop shells revealed a hierarchical micro-ridge structure with sub-micron nano-ridges which promotes directed icing. This concentrates the formation of ice on the growth rings while leaving the regions in between free of ice, and appears to reduce ice-to-shell adhesion when compared to temperate species that do not possess highly ordered surface structures. The ability to control the formation of ice may enable passive underwater anti-icing protection, with the removal of ice possibly facilitated by ocean currents or scallop movements. We term this behavior cryofouling avoidance. We posit that the evolution of natural anti-icing structures is a key trait for the survival of Antarctic scallops in anchor ice zones. This work was supported by the European Union’s Horizon 2020 research and innovation program LubISS No. 722497 (W.S.Y.W.), the German Research Foundation (DFG) with the Priority Programme 2171 (L.H.), the NSF Award No. OPP 1559691 (P.A.C.). The Antarctic fieldwork was supported by the US Antarctic Program under OPP 1559691 to P.A.C. and OPP 1341612 to S. Bowser. We thank S. Bowser, H. Kaiser, and M. Koonce for their assistance in the field, G. Glaser, R. Berger, H. Burg for technical support, A. Naga, D. Vollmer, H.-J. Butt, and M. Bonn for stimulating discussions and the reviewers L. Harper and J. Raymond, whose comments helped to improve this manuscript. Yes
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