rheotaxis

{{Use dmy dates|date=April 2022}}

(Positive) Rheotaxis is a form of taxis seen in many aquatic organisms,{{Cite journal|last1=Elder|first1=John|last2=Coombs|first2=Sheryl|date=2015-05-21|title=The influence of turbulence on the sensory basis of rheotaxis|journal=Journal of Comparative Physiology A|language=en|volume=201|issue=7|pages=667–680|doi=10.1007/s00359-015-1014-7|pmid=25994410|s2cid=17702032|issn=1432-1351}} e.g., fish, whereby they will (generally) turn to face into an oncoming current. In a flowing stream, this behavior leads them to hold their position rather than being swept downstream by the current. Rheotaxis has been noted in zebrafish and other species,{{cite journal|title=A novel mechanism for mechanosensory-based rheotaxis in larval zebrafish|first1=Pablo |last1=Oteiza|first2= Iris |last2=Odstrcil|first3= George |last3=Lauder|first4=Ruben |last4=Portugues |first5= Florian|last5= Engert|journal=Nature|volume=547|issue=7664 |pages=445–448|pmid=28700578 |pmc=5873946 |year=2017 |doi=10.1038/nature23014 }} and is found in most major aquatic invertebrate groups. Rheotaxis is important for animal survival because the positioning of an animal in the water can increase its chance of accessing food and lower the amount of energy it spends, especially when it remains stationary. Some organisms such as eels will exhibit negative rheotaxis where they will turn away from and avoid oncoming currents.{{cite journal|title=Swimming activity and behaviour of European Anguilla anguilla glass eels in response to photoperiod and flow reversal and the role of energy status.|last1=Du Colombier |first1=SB|last2= Bolliet |first2=V|last3= Bardonnet |first3=A|journal=Journal of Fish Biology|volume=74|issue=9|pages=2002–13 |pmid=20735685|doi=10.1111/j.1095-8649.2009.02269.x|year=2009 }} This action is a part of their tendency to want to migrate. Some zooplankton also exhibit positive or negative rheotaxis.{{Cite journal|last1=Holzner|first1=Markus|last2=Souissi|first2=Sami|last3=Fouxon|first3=Itzhak|last4=Michalec|first4=François-Gaël|date=2017-12-26|title=Zooplankton can actively adjust their motility to turbulent flow|journal=Proceedings of the National Academy of Sciences|language=en|volume=114|issue=52|pages=E11199–E11207|doi=10.1073/pnas.1708888114|issn=1091-6490|pmc=5748176|pmid=29229858|bibcode=2017PNAS..11411199M |doi-access=free}}

In fish, the lateral line system is used to determine changes in the oncoming flow pattern of a body of water, and the corresponding orientation of the animal toward or away from the current.{{Cite journal|last1=Brown|first1=Erika E. A.|last2=Simmons|first2=Andrea Megela|date=2016-11-21|title=Variability of Rheotaxis Behaviors in Larval Bullfrogs Highlights Species Diversity in Lateral Line Function|journal=PLOS ONE|language=en|volume=11|issue=11|pages=e0166989|doi=10.1371/journal.pone.0166989|issn=1932-6203|pmc=5117756|pmid=27870909|bibcode=2016PLoSO..1166989B |doi-access=free}} The lateral line sensory system consists of mechanosensory hair cells that detect the movement of water.{{Cite journal|last1=Suli|first1=Arminda|last2=Watson|first2=Glen M.|last3=Rubel|first3=Edwin W.|last4=Raible|first4=David W.|date=2012-02-16|title=Rheotaxis in Larval Zebrafish Is Mediated by Lateral Line Mechanosensory Hair Cells|journal=PLOS ONE|language=en|volume=7|issue=2|pages=e29727|doi=10.1371/journal.pone.0029727|issn=1932-6203|pmc=3281009|pmid=22359538|bibcode=2012PLoSO...729727S |doi-access=free}} Animals can also use rheotaxis in conjunction with other methods to orient themselves in the water. For example, sea lamprey will use the flow of the current to identify upstream chemical stimuli, and position themselves towards the direction of the signal.{{Cite journal|last1=Choi|first1=Jongeun|last2=Jeon|first2=Soo|last3=Johnson|first3=Nicholas S|last4=Brant|first4=Cory O|last5=Li|first5=Weiming|date=2013-11-07|title=Odor-conditioned rheotaxis of the sea lamprey: modeling, analysis and validation|journal=Bioinspiration & Biomimetics|volume=8|issue=4|pages=046011|doi=10.1088/1748-3182/8/4/046011|pmid=24200699|bibcode=2013BiBi....8d6011C |s2cid=15280201 |issn=1748-3182}}

Rheotaxis is also a phenomenon seen in small scale artificial systems. Recently, it was observed that certain self-propelled particles (gold-platinum nanorods) will rheotax and reorient themselves against the flow in small microfluidic channels.{{Cite journal|last1=Baker|first1=Remmi|last2=Kauffman|first2=Joshua E.|last3=Laskar|first3=Abhrajit|last4=Shklyaev|first4=Oleg E.|last5=Potomkin|first5=Mykhailo|last6=Dominguez-Rubio|first6=Leonardo|last7=Shum|first7=Henry|last8=Cruz-Rivera|first8=Yareslie|last9=Aranson|first9=Igor S.|last10=Balazs|first10=Anna C.|last11=Sen|first11=Ayusman|date=2019-06-06|title=Fight the flow: the role of shear in artificial rheotaxis for individual and collective motion|journal=Nanoscale|language=en|volume=11|issue=22|pages=10944–10951|doi=10.1039/C8NR10257K|pmid=31139774|s2cid=206138930 |issn=2040-3372}}