Editing Challenger Deep (section)

==Lifeforms==
The summary report of the {{HMS|Challenger|1858|6}} expedition lists unicellular life forms from the two dredged samples taken when the Challenger Deep was first discovered.<ref>[http://www.19thcenturyscience.org/HMSC/HMSC-Reports/1895-Summary/htm/doc878.html] {{Webarchive|url=https://web.archive.org/web/20110310200116/http://www.19thcenturyscience.org/HMSC/HMSC-Reports/1895-Summary/htm/doc878.html|date=10 March 2011}}, entry on 23 March 1875.</ref> These (''[[Nassellaria]]'' and ''[[Spumellaria]]'') were reported in the Report on Radiolaria (1887)<ref>[http://www.19thcenturyscience.org/HMSC/HMSC-Reports/Zool-40/README.htm] {{Webarchive|url=https://web.archive.org/web/20100729070107/http://www.19thcenturyscience.org/HMSC/HMSC-Reports/Zool-40/README.htm|date=29 July 2010}}, Report on the Radiolaria collected by H.M.S. Challenger
by Ernst Haeckel.</ref> written by [[Ernst Haeckel]].

On their 1960 descent, the crew of the ''Trieste'' noted that the floor consisted of [[diatom]]aceous ooze and reported observing "some type of flatfish" lying on the seabed.<ref>[http://www.americanheritage.com/articles/magazine/it/1992/1/1992_1_28.shtml "To the bottom of the sea"] {{webarchive|url=https://web.archive.org/web/20081203173230/http://www.americanheritage.com/articles/magazine/it/1992/1/1992_1_28.shtml |date=3 December 2008}}, T. A. Heppenheimer, AmericanHeritage.com</ref>

{{blockquote |And as we were settling this final fathom, I saw a wonderful thing. Lying on the bottom just beneath us was some type of [[flatfish]], resembling a [[sole (fish)|sole]], about {{convert|1|ft|cm|disp=sqbr||}} long and {{convert|6|in|cm|disp=sqbr||}} across. Even as I saw him, his two round eyes on top of his head spied us{{spnd}}a monster of steel{{spnd}}invading his silent realm. Eyes? Why should he have eyes? Merely to see phosphorescence? The floodlight that bathed him was the first real light ever to enter this hadal realm. Here, in an instant, was the answer that biologists had asked for the decades. Could life exist in the greatest depths of the ocean? It could! And not only that, here apparently, was a true, bony [[teleost]] fish, not a primitive ray or [[elasmobranch]]. Yes, a highly evolved vertebrate, in time's arrow very close to man himself. Slowly, extremely slowly, this flatfish swam away. Moving along the bottom, partly in the ooze and partly in the water, he disappeared into his night. Slowly too{{spnd}}perhaps everything is slow at the bottom of the sea{{spnd}}Walsh and I shook hands.<ref>''Seven Miles Down: The Story of the Bathyscaph Trieste'' (1961) by J. Piccard and R. S. Dietz. pp. 172–74. Published by Putnam, New York.</ref>}}

Many marine biologists are now skeptical of this supposed sighting, and it is suggested that the creature may instead have been a [[sea cucumber]].<ref>[https://www.theguardian.com/environment/2011/jan/18/james-cameron-dives-deep-avatar "James Cameron dives deep for Avatar"] {{Webarchive|url=https://web.archive.org/web/20170118064643/https://www.theguardian.com/environment/2011/jan/18/james-cameron-dives-deep-avatar |date=18 January 2017 }}, ''Guardian'', 18 January 2011</ref><ref>[http://www.nature.com/news/james-cameron-heads-into-the-abyss-1.10246 "James Cameron heads into the abyss"] {{Webarchive|url=https://web.archive.org/web/20120901025830/http://www.nature.com/news/james-cameron-heads-into-the-abyss-1.10246 |date=1 September 2012 }}, ''Nature'', 19 March 2012</ref> The video camera on board the ''Kaiko'' probe spotted a sea cucumber, a [[Polynoidae|scale worm]] and a [[shrimp]] at the bottom.<ref>Hadfield, Peter (2 November 1996). [https://www.newscientist.com/article/mg15220548.100-mission-to-marianas--if-mount-everest-was-dropped-into-the-worlds-deepest-trench-it-woulddrown-kaiko-hit-bottom----and-came-back-to-tell-the-tale.html "Mission to Marianas"] {{Webarchive|url=https://web.archive.org/web/20150426053914/http://www.newscientist.com/article/mg15220548.100-mission-to-marianas--if-mount-everest-was-dropped-into-the-worlds-deepest-trench-it-woulddrown-kaiko-hit-bottom----and-came-back-to-tell-the-tale.html |date=26 April 2015 }}, ''[[New Scientist]]''.</ref><ref>[https://web.archive.org/web/20081203143936/http://www.time.com/time/magazine/article/0,9171,983295-6,00.html "The last frontier"], ''Time'', 14 August 1995</ref> At the bottom of the Challenger Deep, the ''Nereus'' probe spotted one [[polychaete]] worm (a multi-legged predator) about an inch long.<ref>[http://ns.gov.gu/geography.html Accessed 8 October 2009] {{webarchive|url=https://web.archive.org/web/19961027163532/http://ns.gov.gu/geography.html |date=27 October 1996}} Geography of the ocean floor near Guam with some notes on exploration of the Challenger Deep.</ref>

An analysis of the sediment samples collected by ''Kaiko'' found large numbers of simple organisms at {{convert|10900|m|ft|abbr=on}}.<ref>{{Cite journal|last=Todo |first=Yuko |year=2005 |title=Simple Foraminifera Flourish at the Ocean's Deepest Point |journal=[[Science (journal)|Science]] |volume=307 |issue=5710 |page=689 |doi=10.1126/science.1105407 |pmid=15692042 |s2cid=20003334 |display-authors=etal}}</ref> While similar lifeforms have been known to exist in shallower ocean trenches (> 7,000 m) and on the [[abyssal plain]], the lifeforms discovered in the Challenger Deep possibly represent [[taxon|taxa]] distinct from those in shallower ecosystems.

Most of the organisms collected were simple, soft-shelled [[foraminifera]] (432 species according to National Geographic<ref>{{Cite news |first=John |last=Roach |title=Life Is Found Thriving at Ocean's Deepest Point |url=http://news.nationalgeographic.com/news/2005/02/0203_050203_deepest.html |work=National Geographic News |date=3 February 2005 |access-date=13 July 2007 |archive-date=22 August 2012 |archive-url=https://web.archive.org/web/20120822121902/http://news.nationalgeographic.com/news/2005/02/0203_050203_deepest.html |url-status=dead }}</ref>), with four of the others representing species of the complex, multi-chambered genera ''[[Leptohalysis]]'' and ''[[Reophax]]''. Eighty-five per cent of the specimens were organic, soft-shelled [[allogromiid]]s, which is unusual compared to samples of [[sediment-dwelling organisms]] from other deep-sea environments, where the percentage of [[Foraminifera#Organic-walled|organic-walled foraminifera]] ranges from 5% to 20%. As small organisms with hard, calcareous shells have trouble growing at extreme depths because of the high solubility of [[calcium carbonate]] in the pressurized water, scientists theorize that the preponderance of soft-shelled organisms in the Challenger Deep may have resulted from the typical [[biosphere]] present when the Challenger Deep was shallower than it is now. Over the course of six to nine million years, as the Challenger Deep grew to its present depth, many of the species present in the sediment died out or were unable to adapt to the increasing water pressure and changing environment.<ref>{{cite web|last1=Roach|first1=John|title=Life If Found Thriving at Ocean's Deepest Point|url=http://news.nationalgeographic.com/news/2005/02/0203_050203_deepest.html|website=National Geographic|publisher=National Geographic Society|access-date=17 February 2015|archive-date=22 August 2012|archive-url=https://web.archive.org/web/20120822121902/http://news.nationalgeographic.com/news/2005/02/0203_050203_deepest.html|url-status=dead}}</ref>

On 17 March 2013, researchers reported data that suggested [[Piezophile|piezophilic]] microorganisms thrive in the Challenger Deep.<ref name="LS-20130317">{{cite web |last=Choi |first=Charles Q. |title=Microbes Thrive in Deepest Spot on Earth |url=http://www.livescience.com/27954-microbes-mariana-trench.html |date=17 March 2013 |publisher=[[LiveScience]] |access-date=17 March 2013 |archive-date=16 April 2020 |archive-url=https://web.archive.org/web/20200416081339/https://www.livescience.com/27954-microbes-mariana-trench.html |url-status=live }}</ref><ref name="NG-20130317">{{cite journal |last1=Glud |first1=Ronnie |last2=Wenzhöfer |first2=Frank |last3=Middleboe |first3=Mathias |last4=Oguri |first4=Kazumasa |last5=Turnewitsch |first5=Robert |last6=Canfield |first6=Donald E. |last7=Kitazato |first7=Hiroshi |title=High rates of microbial carbon turnover in sediments in the deepest oceanic trench on Earth |doi=10.1038/ngeo1773 |date=17 March 2013 |journal=[[Nature Geoscience]] |volume=6 |issue=4 |page=284 |bibcode = 2013NatGe...6..284G}}</ref> Other researchers reported related studies that microbes thrive inside rocks up to {{convert|1900|ft|m|0|abbr=on|order=flip}} below the sea floor under {{convert|8500|ft|m|0|abbr=on|order=flip}} of ocean off the coast of the northwestern United States.<ref name="LS-20130317" /><ref name="LS-20130314">{{cite web |last=Oskin |first=Becky |title=Intraterrestrials: Life Thrives in Ocean Floor |url=http://www.livescience.com/27899-ocean-subsurface-ecosystem-found.html |date=14 March 2013 |publisher=[[LiveScience]] |access-date=17 March 2013 |archive-date=16 April 2020 |archive-url=https://web.archive.org/web/20200416081350/https://www.livescience.com/27899-ocean-subsurface-ecosystem-found.html |url-status=live }}</ref> According to one of the researchers, "You can find microbes everywhere{{spnd}}they're extremely adaptable to conditions, and survive wherever they are."<ref name="LS-20130317" />