Adaptive metabolic reprogramming conserves energy status in Antarctic giants.

Polar marine invertebrate giants are proposed to have emerged from the greater availability of environmental oxygen, overcoming the viscosity of cold water and avoiding oxygen poisoning. However, molecular evidence on their metabolic adaptations is lacking to date. Consequently, we characterised the metabolome profiles of a number of marine Antarctic giants and their regular-size relatives exposed acutely in the laboratory either under mean seasonal conditions or elevated temperature. Giants from very distinct taxa share the differential utilisation of metabolic pathways involved in energy production, suggesting an adaptive convergence of metabolic reprogramming to meet the challenge of possessing larger bodies and facing harsh polar conditions. Further, we show that giants are not just larger regular-size species, as indicated by a breakpoint in the allometric relationship for metabolomics scores. Finally, giants do not appear to be more sensitive to ocean warming when compared to their regular-size relatives, all species tested showing no short-term metabolomics reprogramming under elevated temperatures.