Editing Lichen (section)

===Response to environmental stress===
Unlike simple dehydration in plants and animals, lichens may experience a ''complete'' loss of body water in dry periods.<ref name=LLHE/> Lichens are capable of surviving extremely low levels of [[water]] content ([[poikilohydric]]).<ref name="Nash2008-intro"/>{{rp|5–6}} They quickly absorb water when it becomes available again, becoming soft and fleshy.<ref name=LLHE/>

In tests, lichen survived and showed remarkable results on the [[adaptive capacity|adaptation capacity]] of [[photosynthesis|photosynthetic activity]] within the [[simulation|simulation time]] of 34 days under [[Life on Mars (planet)#Life on Earth under Martian conditions|Martian conditions]] in the Mars Simulation Laboratory (MSL) maintained by the [[German Aerospace Center]] (DLR).<ref name="Skymania-20120426">{{cite web |last=Baldwin |first=Emily |title=Lichen survives harsh Mars environment |url=http://www.skymania.com/wp/2012/04/lichen-survives-harsh-martian-setting.html |date=26 April 2012 |publisher=Skymania News |access-date=27 April 2012 |archive-url=https://web.archive.org/web/20120528145425/http://www.skymania.com/wp/2012/04/lichen-survives-harsh-martian-setting.html/ |archive-date=28 May 2012 |url-status=dead }}</ref><ref>{{Cite book|last=Sheldrake|first=Merlin|title=Entangled Life: How Fungi Make Our Worlds, Change Our Minds and Shape Our Futures|publisher=Bodley Head|year=2020|isbn=978-1847925206|pages=94}}</ref>

The [[European Space Agency]] has discovered that lichens can survive unprotected in space. In an experiment led by Leopoldo Sancho from the Complutense University of Madrid, two species of lichen—''[[Rhizocarpon geographicum]]'' and ''[[Rusavskia elegans]]''—were sealed in a capsule and launched on a Russian Soyuz rocket 31 May 2005. Once in orbit, the capsules were opened and the lichens were directly exposed to the vacuum of space with its widely fluctuating temperatures and cosmic radiation. After 15 days, the lichens were brought back to earth and were found to be unchanged in their ability to photosynthesize.<ref name="urlESA - Human Spaceflight and Exploration - Lichen survives in space"/><ref name=Sancho2007/>