Editing Loricifera (section)

==In anoxic environments==
Three species of Loricifera have been found in the oxygen-free sediments at the bottom of the [[L'Atalante basin]] in [[Mediterranean Sea]], more than 3,000&nbsp;meters down, the first multicellular organisms known to spend their entire lives in an anoxic environment. Initially, it was thought that they are able to do this because their [[mitochondria]] act like [[hydrogenosome]]s, allowing them to respire anaerobically.<ref name=Fang-2010-04-08-Nature/><ref name=Milius-2010-04-09-ScienceNews/> However, by 2021, questions arose as to whether or not they have mitochondria.<ref name=Snyder-2021-05-06-Axios/>

The newly reported animals complete their life cycle in the total absence of light and oxygen, and they are less than a millimetre in size.<ref name=Mentel-Martin-2010/> They were collected from a deep basin at the bottom of the Mediterranean Sea, where they inhabit a nearly salt-saturated [[brine]] that, because of its density (>&nbsp;1.2&nbsp;g/cm<sup>3</sup>), does not mix with the waters above.<ref name=Mentel-Martin-2010/> As a consequence, this environment is completely anoxic and, due to the activity of [[sulfate]] reducers, contains sulphide at a concentration of 2.9&nbsp;mM.<ref name=Mentel-Martin-2010/> Despite such harsh conditions, this anoxic and sulphidic environment is teeming with microbial life, both chemosynthetic prokaryotes that are [[primary producer]]s, and a broad diversity of eukaryotic [[heterotroph]]s at the next [[trophic level]].<ref name=Mentel-Martin-2010/>