Hirondellea gigas lives on the floor of hadal trenches, where the only reliable energy comes from above. Carcasses, marine snow and terrestrial plant material sink into the trench and are consumed by dense swarms of amphipods that reach baited landers within minutes.
Analysis of the animals' gut contents has recovered cellulases and related enzymes capable of breaking down woody plant material, alongside sawdust-like fragments. That is unexpected for a marine scavenger, since digesting cellulose is uncommon among animals and normally depends on symbiotic microbes. The finding implies that wood and other plant debris washed off land is a real component of the hadal food supply, not an occasional novelty.
Surviving the pressure requires separate chemistry. Deep-living amphipods accumulate organic osmolytes that stabilise proteins under compression, and hadal species carry unusually high concentrations. There is also an unwelcome finding attached to these animals: amphipods sampled from the Mariana and Kermadec trenches have been found to carry high concentrations of persistent organic pollutants, showing that the deepest habitats are not isolated from surface contamination.