View source for Biology:Taxis

{{short description|Directed movement of a motile cell or organism in response to an external stimulus}}

A '''taxis''' ({{etymology|grc|''τάξις'' (táxis)|arrangement, order}};<ref>{{cite encyclopedia |url=https://www.perseus.tufts.edu/hopper/text?doc=Perseus:text:1999.04.0057:entry=ta/cis |title=τάξις |encyclopedia=A Greek–English Lexicon |author=Henry George Liddell |author2=Robert Scott |publisher=Clarendon Press |location=Oxford |year=1940}}</ref> {{plural form}}: '''taxes''' {{IPAc-en|ˈ|t|æ|k|s|i:|z}})<ref>{{cite web |url=http://www.thefreedictionary.com/taxis |title=taxis |via=[[The Free Dictionary]]}}</ref><ref>{{cite Merriam-Webster|taxis}}</ref><ref>{{cite Dictionary.com|taxis}}</ref> is the [[Biology:Motility|movement]] of an organism in response to a [[Biology:Stimulus (physiology)|stimulus]] such as light or the presence of food. Taxes are innate behavioural responses. A taxis differs from a [[Biology:Tropism|tropism]] (turning response, often growth towards or away from a stimulus) in that in the case of taxis, the organism has [[Biology:Motility|motility]] and demonstrates guided movement towards or away from the stimulus source.<ref>{{cite book |author=Kendeigh, S. C. |year=1961 |title=Animal Ecology |url=https://archive.org/details/ost-biology-animalecology00kend |publisher=Prentice-Hall, Inc., Englewood Cliffs, N.J. |pages=[https://archive.org/details/ost-biology-animalecology00kend/page/n481 468] pp}}</ref><ref>Dusenbery, David B. (2009). ''Living at Micro Scale'', Ch. 14. Harvard University Press, Cambridge, Massachusetts {{ISBN|978-0-674-03116-6}}.</ref> It is sometimes distinguished from a [[Philosophy:Kinesis|kinesis]], a non-directional change in activity in response to a stimulus.

== Classification ==
Taxes are classified based on the type of stimulus, and on whether the organism's response is to move towards or away from the stimulus. If the organism moves towards the stimulus the taxis are positive, while if it moves away the taxis are negative. For example, flagellate [[Biology:Protozoa|protozoa]]ns of the genus ''[[Biology:Euglena|Euglena]]'' move towards a light source. This reaction or behavior is called ''positive phototaxis'' since phototaxis refers to a response to light and the organism is moving towards the stimulus.

=== Terminology derived from type of stimulus ===
Many types of taxis have been identified, including:
* ''[[Chemistry:Aerotaxis|Aerotaxis]]'' (stimulation by [[Chemistry:Oxygen|oxygen]])
* ''Anemotaxis'' (by [[Earth:Wind|wind]])<ref name="Mackenzie"/>
* ''Barotaxis'' (by [[Physics:Pressure|pressure]])
* ''[[Physics:Chemotaxis|Chemotaxis]]'' or "gradient search" (by chemicals)<ref name="Mackenzie">{{cite journal |last1=Mackenzie |first1=Dana |title=How animals follow their nose |journal=Knowable Magazine |publisher=Annual Reviews |date=6 March 2023 |doi=10.1146/knowable-030623-4 |doi-access=free |url=https://knowablemagazine.org/article/living-world/2023/how-animals-follow-their-nose |access-date=13 March 2023 |language=en}}</ref>
* ''[[Philosophy:Durotaxis|Durotaxis]]'' (by [[Physics:Stiffness|stiffness]])
* ''Electrotaxis'' or ''galvanotaxis'' (by [[Physics:Electric current|electric current]])
* ''[[Philosophy:Gravitaxis|Gravitaxis]]'' or ''geotaxis'' (by [[Physics:Gravity|gravity]])
* ''Hydrotaxis'' (by [[Earth:Moisture|moisture]])
* ''[[Physics:Magnetotaxis|Magnetotaxis]]'' (by [[Physics:Magnetic field|magnetic field]])
* ''[[Biology:Phototaxis|Phototaxis]]'' (by [[Physics:Light|light]])
* ''[[Biology:Rheotaxis|Rheotaxis]]'' (by [[Physics:Fluid flow|fluid flow]])
* ''Thermotaxis'' (by changes in [[Physics:Temperature|temperature]])
* ''Thigmotaxis'' (by physical contact)

Depending on the type of sensory organs present, a taxis can be classified as a ''klinotaxis'', where an organism continuously samples the environment to determine the direction of a stimulus; a ''tropotaxis'', where bilateral sense organs are used to determine the stimulus direction; and a ''telotaxis'', where a single organ suffices to establish the orientation of the stimulus.

=== Terminology derived from taxis direction ===
There are five types of taxes based on the movement of organisms.

* ''Klinotaxis'' occurs in organisms with receptor cells but not paired receptor organs. The cells for reception may be located all over the body, but often towards the anterior side. The organism detects the [[Biology:Stimulus (physiology)|stimuli]] by turning its head sideways and comparing the intensity of the stimulus. Their direction of movement is then based on the stronger stimulus, either moving toward a desirable stimulus or away from an undesired one.<ref name="Mackenzie"/> When the intensity of stimuli is balanced equally from all sides, the organism moves in a straight line. The movement of [[Biology:Calliphoridae|blowfly]] and [[Biology:Butterfly|butterfly]] [[Biology:Larva|larva]]e clearly demonstrates klinotaxis.
* ''Tropotaxis'' is displayed by organisms with paired receptor cells, comparing the strength of the signals and turning toward the strongest signal.<ref name="Mackenzie"/>  The movement of grayling butterflies and fish lice clearly demonstrates tropotaxis.
* ''Telotaxis'' also requires paired receptors. The movement occurs along the direction where the intensity of the stimuli is stronger. Telotaxis is clearly seen in the movement of [[Biology:Bee|bee]]s when they leave their hive to look for food. They balance the stimuli from the sun as well as from [[Biology:Flower|flower]]s but land on the flower whose stimulus is most intense for them.
* ''Menotaxis'' describes organisms' maintenance of a constant [[Orientation (geometry)|angular orientation]]. A clear demonstration is shown by bees returning to their hive at night and the movement of ants with respect to the sun.
* ''Mnemotaxis'' is the use of [[Memory|memory]] to follow trails that organisms have left when travelling to or from their home.

== Examples ==
<!--Alphabetical:-->

* Aerotaxis is the response of an organism to variation in oxygen concentration, and is mainly found in aerobic bacteria.<ref name=Martin1983>{{Cite book|editor=Martin, E.A.|year=1983|title=Macmillan Dictionary of Life Sciences| edition=2nd| page=362 |place=London |publisher=Macmillan Press|isbn=0-333-34867-2}}</ref>
* Anemotaxis is the response of an organism to wind. Many insects show a positive anemotactic response (turning/flying into the wind) upon exposure to an airborne stimulus cue from a food source or pheromones.<ref name="Mackenzie"/> Cross-wind anemotactic search is exhibited by some olfactory animals in the absence of a target odor including moths, albatrosses, and polar bears.<ref>{{cite journal |last1=Kennedy |first1=J. S. |last2=Marsh |first2=D. |title=Pheromone-regulated anemotaxis in flying moths |journal=Science |date=1974 |volume=184 |issue=4140 |pages=999–1001 |doi=10.1126/science.184.4140.999|pmid=4826172 |bibcode=1974Sci...184..999K |s2cid=41768056 }}</ref><ref>{{cite journal |last1=Nevitt |first1=Gabrielle A. |last2=Losekoot |first2=Marcel |last3=WeimerskirchWeimerskirch |first3=Henri |title=Evidence for olfactory search in wandering albatross, Diomedea exulans |journal=PNAS |date=2008 |volume=105 |issue=12 |pages=4576–4581|pmc=2290754 |doi=10.1073/pnas.0709047105|pmid=18326025 |doi-access=free }}</ref><ref>{{cite journal |last1=Togunov |first1=Ron |title=Windscapes and olfactory foraging in a large carnivore |journal=Scientific Reports |date=2017 |volume=7 |page=46332 |doi=10.1038/srep46332|pmid=28402340 |pmc=5389353 |bibcode=2017NatSR...746332T }}</ref>
* [[Physics:Chemotaxis|Chemotaxis]] is a response elicited by chemicals: that is, a response to a chemical concentration gradient.<ref name=Martin1983/><ref name="Mackenzie"/><ref name="Reddy">{{cite journal |last1=Reddy |first1=Gautam |last2=Murthy |first2=Venkatesh N. |last3=Vergassola |first3=Massimo |title=Olfactory Sensing and Navigation in Turbulent Environments |journal=Annual Review of Condensed Matter Physics |date=10 March 2022 |volume=13 |issue=1 |pages=191–213 |doi=10.1146/annurev-conmatphys-031720-032754 |bibcode=2022ARCMP..13..191R |s2cid=243966350 |url=https://www.annualreviews.org/doi/10.1146/annurev-conmatphys-031720-032754 |language=en |issn=1947-5454}}</ref> For example, chemotaxis in response to a sugar gradient has been observed in motile bacteria such as [[Biology:Escherichia coli|''E. coli'']].<ref name=Blass1987>{{Cite book|author=Blass, E.M|year=1987|editor=Dobbing, J|chapter=Opioids, sweets and a mechanism for positive affect: Broad motivational implications|title=Sweetness|pages=115–124|place= London |publisher= Springer-Verlag|isbn=0-387-17045-6}}</ref> Chemotaxis also occurs in the [[Biology:Antheridium|antherozoids]] of [[Biology:Marchantiophyta|liverworts]], [[Biology:Fern|fern]]s, and mosses in response to chemicals secreted by the [[Biology:Archegonium|archegonia]].<ref name=Martin1983/> Unicellular (e.g. protozoa) or multicellular (e.g. worms) organisms are targets of chemotactic substances. A concentration gradient of chemicals developed in a fluid phase guides the vectorial movement of responder cells or organisms. Inducers of locomotion towards increasing steps of concentrations are considered as chemoattractants, while chemorepellents result moving off the chemical. Chemotaxis is described in [[Biology:Prokaryote|prokaryotic]] and [[Biology:Eukaryote|eukaryotic]] cells, but signalling mechanisms (receptors, intracellular signaling) and effectors are significantly different.
* [[Philosophy:Durotaxis|Durotaxis]] is the directional movement of a cell along a stiffness gradient.
* Electrotaxis (or galvanotaxis) is the directional movement of motile cells along the vector of an [[Physics:Electric field|electric field]]. It has been suggested that by detecting and orienting themselves toward the electric fields, cells can move towards damages or wounds to repair them. It also is suggested that such a movement may contribute to directional growth of cells and tissues during development and regeneration. This notion is based on the existence of measurable electric fields that naturally occur during wound healing, development and regeneration; and cells in cultures respond to applied electric fields by directional cell migration – electrotaxis&nbsp;/ galvanotaxis.
* Energy taxis is the orientation of bacteria towards conditions of optimal metabolic activity by sensing the internal energetic conditions of cell. Therefore, in contrast to chemotaxis (taxis towards or away from a specific extracellular compound), energy taxis responds on an intracellular stimulus (e.g. proton motive force, activity of [[Biology:NADH dehydrogenase|NDH- 1]]) and requires metabolic activity.<ref>Schweinitzer T, Josenhans C. [https://doi.org/10.1007%2Fs00203-010-0575-7 Bacterial energy taxis: a global strategy?] Arch Microbiol. 2010 Jul;192(7):507-20.</ref>
* [[Philosophy:Gravitaxis|Gravitaxis]] (known historically as geotaxis) is the directional movement (along the vector of [[Physics:Gravity|gravity]]) to the center of gravity. The [[Earth:Plankton|plankton]]ic larvae of a [[Biology:King crab|king crab]], ''Lithodes aequispinus'', combine positive phototaxis (movement towards the light) and negative gravitaxis (upward movement).<ref>{{cite journal |title=Phototaxis and geotaxis of light-adapted zoeae of the golden king crab ''Lithodes aequispinus'' (Anomura: Lithodidae) in the laboratory |author=C. F. Adams & A. J. Paul |jstor=1549552 |year=1999 |journal=Journal of Crustacean Biology |volume=19 |issue=1 |pages=106–110 |doi=10.2307/1549552}}</ref> Also the larvae of a [[Biology:Polychaete|polychaete]], ''[[Biology:Platynereis dumerilii|Platynereis dumerilii]]'', combine positive phototaxis (movement to the light coming from the water surface) and UV-induced positive gravitaxis (downward movement) to form a ratio-chromatic [[Depth gauge|depth-gauge]].<ref name="Veraszto2018">{{cite journal |last1=Verasztó |first1=Csaba |last2=Gühmann |first2=Martin |last3=Jia |first3=Huiyong |last4=Rajan |first4=Vinoth Babu Veedin |last5=Bezares-Calderón |first5=Luis A. |last6=Piñeiro-Lopez |first6=Cristina |last7=Randel |first7=Nadine |last8=Shahidi |first8=Réza |last9=Michiels |first9=Nico K. |last10=Yokoyama |first10=Shozo |last11=Tessmar-Raible |first11=Kristin |last12=Jékely |first12=Gáspár |title=Ciliary and rhabdomeric photoreceptor-cell circuits form a spectral depth gauge in marine zooplankton |journal=eLife |date=29 May 2018 |volume=7 |doi=10.7554/eLife.36440 |pmid=29809157 |pmc=6019069 |doi-access=free }}</ref> Both positive and negative gravitaxes are found in a variety of [[Biology:Protozoa|protozoa]]ns (''e.g.'', ''[[Biology:Loxodes|Loxodes]]'', ''[[Biology:Remanella|Remanella]]'' and ''[[Biology:Paramecium|Paramecium]]'').<ref>{{cite journal |url=http://jeb.biologists.org/cgi/reprint/110/1/17 |author=T. Fenchel & B. J. Finlay |title=Geotaxis in the ciliated protozoon ''Loxodes'' |journal=Journal of Experimental Biology |date=1 May 1984|volume=110 |pages=110–133 |issue=1 |doi=10.1242/jeb.110.1.17 |doi-access=free }}</ref>
* [[Physics:Magnetotaxis|Magnetotaxis]] is, strictly speaking, the ability to sense a [[Physics:Magnetic field|magnetic field]] and coordinate movement in response. However, the term is commonly applied to bacteria that contain magnets and are physically rotated by the force of [[Earth:Earth's magnetic field|Earth's magnetic field]]. In this case, the "behaviour" has nothing to do with sensation and the bacteria are more accurately described as "magnetic bacteria".<ref>Dusenbery, David B. (2009). ''Living at Micro Scale'', pp.164–167. Harvard University Press, Cambridge, Massachusetts {{ISBN|978-0-674-03116-6}}.</ref>
* Pharotaxis is the movement to a specific location in response to learned or conditioned stimuli, or navigation by means of landmarks.<ref>{{citation| title=pharotaxis at Word Info | url=http://wordinfo.info/results/pharotaxis}}</ref><ref>{{Cite book|author=Barrows, Edward M. |year=2011 |publisher=CRC Press|edition=3, illustrated, revised|isbn=978-1-4398-3652-1|title=Animal Behavior Desk Reference: A Dictionary of Animal Behavior, Ecology, and Evolution, Third Edition|page=463|url=https://books.google.com/books?id=yaXMBQAAQBAJ&q=pharotaxis&pg=PA463}}</ref>
* Phonotaxis is the movement of an organism in response to [[Physics:Sound|sound]].
* [[Biology:Phototaxis|Phototaxis]] is the movement of an organism in response to [[Physics:Light|light]]: that is, the response to variation in light intensity and direction.<ref name=Martin1983/><ref name=Menzel1979>{{Cite book|author=Menzel, Randolf|year=1979|editor=H. Autrum|chapter=Spectral Sensitivity and Color Vision in Invertebrates |title=Comparative Physiology and Evolution of Vision in Invertebrates- A: Invertebrate Photoreceptors|location=New York|series=Handbook of Sensory Physiology|volume=VII/6A|pages=503–580. See section D: Wavelength–Specific Behavior and Color Vision|publisher=Springer-Verlag|isbn=3-540-08837-7}}</ref> Negative phototaxis, or movement away from a light source, is demonstrated in some insects, such as cockroaches.<ref name=Martin1983/> Positive phototaxis, or movement towards a light source, is advantageous for phototrophic organisms as they can orient themselves most efficiently to receive light for [[Earth:Photosynthesis|photosynthesis]]. Many phytoflagellates, e.g. ''[[Biology:Euglena|Euglena]]'', and the [[Biology:Chloroplast|chloroplast]]s of higher plants positively phototactic, moving towards a light source.<ref name=Martin1983/> Two types of positive phototaxis are observed in prokaryotes: scotophobotaxis is observable as the movement of a bacterium out of the area illuminated by a microscope, when entering darkness signals the cell to reverse direction and reenter the light; a second type of positive phototaxis is true phototaxis, which is a directed movement up a gradient to an increasing amount of light. There is a different classification to orientation towards dark areas called scototaxis.
* [[Biology:Rheotaxis|Rheotaxis]] is a response to a [[Physics:Fluid dynamics|current]] in a fluid. Positive rheotaxis is shown by fish turning to face against the current. In a flowing stream, this behaviour leads them to hold their position in a stream rather than being swept downstream. Some fish will exhibit negative rheotaxis where they will avoid currents.
* Thermotaxis is a migration along a gradient of temperature. Some [[Biology:Slime mold|slime mold]]s and small [[Biology:Nematode|nematode]]s can migrate along amazingly small temperature gradients of less than 0.1&nbsp;°C/cm.<ref>Dusenbery, David B. (1992). ''Sensory Ecology'', p.114. W.H. Freeman, New York. {{ISBN|0-7167-2333-6}}.</ref> They apparently use this behaviour to move to an optimal level in soil.<ref>Dusenbery, D.B. ''Behavioral Ecology and Sociobiology'', 22:219–223 (1988). "Avoided temperature leads to the surface:…"</ref><ref>Dusenbery, D.B. ''Biological Cybernetics'', 60:431–437 (1989). "A simple animal can use a complex stimulus patter to find a location:…"</ref>
* Thigmotaxis is the response of an organism to physical contact or to the proximity of a physical discontinuity in the environment (e.g. rats preferring to swim near the edge of a water maze). [[Biology:Codling moth|Codling moth]] larvae are believed to use thigmotactic sense to locate fruits to feed on.<ref>{{Cite journal|last=Jackson|first=D. Michael|date=1982-05-15|title=Searching Behavior and Survival of 1st-Instar Codling Moths|url=https://academic.oup.com/aesa/article/75/3/284/171789|journal=Annals of the Entomological Society of America|volume=75|issue=3|pages=284–289|doi=10.1093/aesa/75.3.284|issn=0013-8746}}</ref> Mice and rats, when inhabiting human-made structures, tend to stick close to vertical surfaces; this primarily manifests as running along the floor/wall juncture. Whiskers ([[Biology:Whiskers|vibrissae]]) are often used to detect the presence of a wall or surface in the absence of sufficient light in rodents and felines to aid in thigmotaxis.

== See also ==
;Biology
* [[Biology:Animal locomotion|Animal locomotion]]
* [[Biology:Haptotaxis|Haptotaxis]]
* [[Biology:Mechanotaxis|Mechanotaxis]]
* [[Biology:Optomotor response|Optomotor response]]
* [[Biology:Tropism|Tropism]]
;Different, wider context
* [[Taxonomy]], science of categorisation or classification

== References ==
{{reflist}}

== External links ==
* [http://www.olfacts.nl/repL/JIP88.pdf Host-plant finding by insects: orientation, sensory input and search patterns]

{{Taxes (Biology)}}

[[Category:Cell biology]]

{{Sourceattribution|Taxis}}