Electron microscopic analysis of the exo-skeleton of hadal zone amphipodHirondellea gigas

Abstract

AbstractThe amphipodHirondellea gigasinhabits the deepest regions of the oceans in extra high-pressure. However, the mechanisms by which they adapt to their high-pressure environments remain unknown. In this study, we investigated elements of the exoskeleton ofH. gigascaptured from the deepest points of the Mariana Trench. TheH. gigasexoskeleton contained aluminum, as well as a major amount of calcium carbonate. Unlike other accumulated metals, aluminum was distributed on the surface of exoskeletons. To investigate howH. gigasobtains aluminum, we conducted a metabolome analysis and found that gluconic acid/gluconolactone was capable of extracting metals from the sediment under the habitat conditions ofH. gigas. The extracted aluminum ions are transformed into the gel state of aluminum hydroxide in alkaline seawater, and this gel covers the body to protect the amphipod. The aluminum gel would be one of good materials to adapt to such high-pressure environment.