Sara J. Shettleworth

researchers discovered a new species of snailfish inhabiting trenches there with each trench home to its own species of the fish. “To test whether these species would be found in all trenches, we repeated our experiments on the other side of the Pacific Ocean, some 6,000 miles from our last observations,” said Jamieson. During the three-week expedition of the research vessel Sonne, the researchers used state-of-theart deep-sea imaging technology, including an ultra-deep free-falling baited camera system, to take images deep into the trench. A species of cusk eel gathered at the camera and fed on the bait for the full day of deployment. “Further research needs to be conducted to decipher whether this is an entirely new species of cusk eel that we have discovered,” the researchers said. The expedition was the seventh to take place as part of Hadeep, a collaborative research project between the University of Aberdeen’s Oceanlab, the University of Tokyo’s Ocean Research Institute and with support from New Zealand’s National Institute of Water and Atmospheric Research (Niwa). The Hadeep team has been investigating extreme depths across the globe for three years. The results have been photographs of the world’s deepest-living fish for the first time. The team also discovered a species of amphipod crustacean scavengers which they previously did not know existed at such depths and in such great numbers. Niamh Kilgallen, an amphipod expert from Niwa said: “The sheer abundance of these big amphipods was overwhelming, particularly at 7,000–8,000 metres, which is much deeper than they have been found in any other trench. It begs the question of why and how they can live so deep in this trench but not in any other.” These findings “prompt a reevaluation of the diversity and abundance of life at extreme depths,” said Jamieson. “Each of the deep trenches across the globe hosts a unique assembly of animals which can differ greatly from trench to trench. The immense isolation of each trench draws parallels with island evolution popularised by Darwin’s finches,” he said. Sara J. Shettleworth