National Oceanography Centre, University of Southampton Waterfront Campus, Southampton, UK.
Imaging and Analysis Centre, Natural History Museum, London, UK.
Sci Rep. 2018 Aug 14;8(1):12103. doi: 10.1038/s41598-018-30186-2.
Xenophyophores, giant foraminifera, are distinctive members of the deep-sea megafauna that accumulate large masses of waste material ('stercomare') within their agglutinated tests, and organise their cells as branching strands enclosed within an organic tube (the 'granellare' system). Using non-destructive, three-dimensional micro-CT imaging we explored these structures in three species from the abyssal eastern Pacific Clarion-Clipperton Zone (CCZ). In Psammina spp., the low-density stercomare occupied much of the test interior, while high-density granellare strands branched throughout the structure. In Galatheammina sp. the test comprised a mixture of stercomare and test particles, with the granellare forming a web-like system of filaments. The granellare occupied 2.8-5.1%, the stercomare 72.4-82.4%, and test particles 14.7-22.5%, of the 'body' volume in the two Psammina species. The corresponding proportions in Galatheammina sp. were 1.7% (granellare), 39.5% (stercomare) and 58.8% (test particles). These data provide a potential basis for estimating the contribution of xenophyophores to seafloor biomass in areas like the CCZ where they dominate the megafauna. As in most xenophyophore species, the granellare hosted huge numbers of tiny barite crystals. We speculate that these help to support the extensive granellare system, as well as reducing the cell volume and lightening the metabolic burden required to maintain it.
海绵骨针，巨型有孔虫，是深海巨型动物群中的独特成员，它们在其胶结的壳体内积累大量废物（“stercomare”），并将其细胞组织成分支链，被包裹在有机管内（“granellare”系统）。使用非破坏性的三维微 CT 成像技术，我们在来自东太平洋克拉里昂-克利珀顿区（CCZ）深海的三个物种中研究了这些结构。在 Psammina 属中，低密度的 stercomare 占据了大部分壳体内腔，而高密度的 granellare 分支链贯穿整个结构。在 Galatheammina 属中，壳体由 stercomare 和壳粒的混合物组成，granellare 形成了一个丝状的网络系统。在两个 Psammina 物种中，granellare 占“身体”体积的 2.8-5.1%，stercomare 占 72.4-82.4%，壳粒占 14.7-22.5%。在 Galatheammina 属中，相应的比例分别为 1.7%（granellare）、39.5%（stercomare）和 58.8%（壳粒）。这些数据为估计 CCZ 等地区 xenophyophores 对海底生物量的贡献提供了潜在的依据，因为在这些地区它们是巨型动物群的主要组成部分。与大多数 xenophyophore 物种一样，granellare 内含有大量微小的重晶石晶体。我们推测这些晶体有助于支撑广泛的 granellare 系统，同时减少细胞体积，并减轻维持该系统所需的代谢负担。
