The specimens of Coryphaenoides armatus from yesterday and Coryphaenoides yaquinae today are helping to piece together our understanding of the distribution of deep-sea fishes. Although C. armatus was known to occur, the specimens have confirmed it is relatively abundant in deep New Zealand areas (based on camera work). C. yaquinae is known from the North Pacific, (including the Japan and Mariana Trenches) and off Chile and Peru. But this is the first record in the Southwest Pacific, and proves a widespread Pacific rim distribution. For all of us onboard these are exciting results. Amphipods haven't featured much in the reports to date. But we are now approaching depths where things get interesting. The main species we have seen so far is Eurythenes gryllus, a worldwide species, and the second largest only to the "supergiant" Alicella. There was a good catch today, but we expect numbers to decrease as we go deeper onto the Trench. While in other trench systems Eurythenes is found as deep as 7000m, in the Kermadec Trench it hasn't been found past 6000m, where we see other amphipod species dominate. We don't know why, although one possibility being studied on this trip through genetic studies is the possibility that there is more than one species with different depth ranges, but they look the same-so-called "cryptic" species.This afternoon we deployed the gear at around 6000m, and if the weather holds we hope to go deeper still the following day - into the Trench proper - to improve our knowledge of how faunal communities change in the deep.Previously in this series:Kermadec Trench: Cook, Kermadec and KaharoaPrevious research in the Kermadec TrenchKermadec Trench: Scuttling your AssetsKermadec Trench: Boring eelsKermadec Trench: The Cosmopolitan RattailKermadec Trench: The deep-water womble Follow Scientific American on Twitter @SciAm and @SciamBlogs. Visit ScientificAmerican.com for the latest in science, health and technology news.
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