02113nas a2200241   4500008004100000020001400041245006600055210006600121260000800187300001000195490000800205520145700213100001701670700002201687700001801709700001301727700001501740700002001755700001501775700001601790700002001806856004501826       2011                        eng d  a0028-083600aNematoda from the terrestrial deep subsurface of South Africa0 aNematoda from the terrestrial deep subsurface of South Africa  cJun  a79-820 v4743 aSince its discovery over two decades ago, the deep subsurface biosphere has been considered to be the realm of single-cell organisms, extending over three kilometres into the Earth's crust and comprising a significant fraction of the global biosphere(1-4). The constraints of temperature, energy, dioxygen and space seemed to preclude the possibility of more-complex, multicellular organisms from surviving at these depths. Here we report species of the phylum Nematoda that have been detected in or recovered from 0.9-3.6-kilometre-deep fracture water in the deep mines of South Africa but have not been detected in the mining water. These subsurface nematodes, including a new species, Halicephalobus mephisto, tolerate high temperature, reproduce asexually and preferentially feed upon subsurface bacteria. Carbon-14 data indicate that the fracture water in which the nematodes reside is 3,000-12,000-year-old palaeometeoric water. Our data suggest that nematodes should be found in other deep hypoxic settings where temperature permits, and that they may control the microbial population density by grazing on fracture surface biofilm patches. Our results expand the known metazoan biosphere and demonstrate that deep ecosystems are more complex than previously accepted. The discovery of multicellular life in the deep subsurface of the Earth also has important implications for the search for subsurface life on other planets in our Solar System.1 aBorgonie, G.1 aGarcia-Moyano, A.1 aLitthauer, D.1 aBert, W.1 aBester, A.1 avan Heerden, E.1 aMoller, C.1 aErasmus, M.1 aOnstott, T., C.  uhttps://nematodes.myspecies.info/node/82