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A taxis (; ) is the
movement Movement may refer to: Common uses * Movement (clockwork), the internal mechanism of a timepiece * Motion, commonly referred to as movement Arts, entertainment, and media Literature * "Movement" (short story), a short story by Nancy Fu ...
of an organism in response to a stimulus such as light or the presence of food. Taxes are
innate behaviour Instinct is the inherent inclination of a living organism towards a particular complex behaviour, containing both innate (inborn) and learned elements. The simplest example of an instinctive behaviour is a fixed action pattern (FAP), in which a ve ...
al responses. A taxis differs from a tropism (turning response, often growth towards or away from a stimulus) in that in the case of taxis, the organism has motility and demonstrates guided movement towards or away from the stimulus source. It is sometimes distinguished from a 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
protozoa Protozoa (singular: protozoan or protozoon; alternative plural: protozoans) are a group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic tissues and debris. Histo ...
ns of the genus '' 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. Many types of taxis have been identified, including: * '' Aerotaxis'' (stimulation by oxygen) * ''Anemotaxis'' (by wind) * ''Barotaxis'' (by pressure) * ''
Chemotaxis Chemotaxis (from '' chemo-'' + ''taxis'') is the movement of an organism or entity in response to a chemical stimulus. Somatic cells, bacteria, and other single-cell or multicellular organisms direct their movements according to certain chemica ...
'' (by chemicals) * ''
Durotaxis Durotaxis is a form of cell migration in which cells are guided by rigidity gradients, which arise from differential structural properties of the extracellular matrix (ECM). Most normal cells migrate up rigidity gradients (in the direction of great ...
'' (by
stiffness Stiffness is the extent to which an object resists deformation in response to an applied force. The complementary concept is flexibility or pliability: the more flexible an object is, the less stiff it is. Calculations The stiffness, k, of a b ...
) * ''
Electrotaxis Electrotaxis, also known as galvanotaxis, is the directed motion of biological cells or organisms guided by an electric field or current. The directed motion of electrotaxis can take many forms, such as; growth, development, active swimming, and p ...
'' or ''galvanotaxis'' (by
electric current An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The moving pa ...
) * ''
Gravitaxis Gravitaxis (or ''geotaxis'') is a form of taxis characterized by the directional movement of an organism in response to gravity. Gravitaxis is one of the many forms of taxis. It is characterized by the movement of an organism in response to gravita ...
'' or ''geotaxis'' (by gravity) * ''Hydrotaxis'' (by moisture) * '' Magnetotaxis'' (by
magnetic field A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...
) * '' Phototaxis'' (by light) * ''
Rheotaxis (Positive) Rheotaxis is a form of taxis seen in many aquatic organisms, 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 do ...
'' (by
fluid flow In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids— liquids and gases. It has several subdisciplines, including ''aerodynamics'' (the study of air and other gases in motion) an ...
) * ''
Thermotaxis Thermotaxis is a behavior in which an organism directs its locomotion up or down a gradient of temperature. Lab research has determined that some slime molds and small nematodes (namely Meloidogyne incognita) can migrate along amazingly shallow t ...
'' (by changes in temperature) * ''Thigmotaxis'' (by
physical contact In physiology, the somatosensory system is the network of neural structures in the brain and body that produce the perception of touch (haptic perception), as well as temperature (thermoception), body position (proprioception), and pain. It i ...
) Depending on the type of
sensory organ A sense is a biological system used by an organism for sensation, the process of gathering information about the world through the detection of stimuli. (For example, in the human body, the brain which is part of the central nervous system rec ...
s 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.


Examples

* Aerotaxis is the response of an organism to variation in oxygen concentration, and is mainly found in aerobic bacteria. * 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. Cross-wind anemotactic search is exhibited by some olfactory animals in the absence of a target odor including moths, albatrosses, and polar bears. *
Chemotaxis Chemotaxis (from '' chemo-'' + ''taxis'') is the movement of an organism or entity in response to a chemical stimulus. Somatic cells, bacteria, and other single-cell or multicellular organisms direct their movements according to certain chemica ...
is a response elicited by chemicals: that is, a response to a chemical concentration gradient. For example, chemotaxis in response to a sugar gradient has been observed in motile bacteria such as ''E. coli''. Chemotaxis also occurs in the antherozoids of
liverworts The Marchantiophyta () are a division of non-vascular land plants commonly referred to as hepatics or liverworts. Like mosses and hornworts, they have a gametophyte-dominant life cycle, in which cells of the plant carry only a single set of ge ...
, ferns, and
mosses Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophyta (, ) ''sensu stricto''. Bryophyta (''sensu lato'', Schimp. 1879) may also refer to the parent group bryophytes, which comprise liverworts, mosses, and horn ...
in response to chemicals secreted by the
archegonia An archegonium (pl: archegonia), from the ancient Greek ''ἀρχή'' ("beginning") and ''γόνος'' ("offspring"), is a multicellular structure or organ of the gametophyte phase of certain plants, producing and containing the ovum or female ga ...
. 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
chemoattractant Chemotaxis (from '' chemo-'' + ''taxis'') is the movement of an organism or entity in response to a chemical stimulus. Somatic cells, bacteria, and other single-cell or multicellular organisms direct their movements according to certain chemical ...
s, while
chemorepellent Chemotaxis (from '' chemo-'' + ''taxis'') is the movement of an organism or entity in response to a chemical stimulus. Somatic cells, bacteria, and other single-cell or multicellular organisms direct their movements according to certain chemica ...
s result moving off the chemical. Chemotaxis is described in prokaryotic and eukaryotic cells, but signalling mechanisms (receptors, intracellular signaling) and effectors are significantly different. *
Durotaxis Durotaxis is a form of cell migration in which cells are guided by rigidity gradients, which arise from differential structural properties of the extracellular matrix (ECM). Most normal cells migrate up rigidity gradients (in the direction of great ...
is the directional movement of a cell along a stiffness gradient. *
Electrotaxis Electrotaxis, also known as galvanotaxis, is the directed motion of biological cells or organisms guided by an electric field or current. The directed motion of electrotaxis can take many forms, such as; growth, development, active swimming, and p ...
(or galvanotaxis) is the directional movement of motile cells along the vector of an
electric field An electric field (sometimes E-field) is the physical field that surrounds electrically charged particles and exerts force on all other charged particles in the field, either attracting or repelling them. It also refers to the physical field fo ...
. 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 / 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 NDH- 1) and requires metabolic activity. *
Gravitaxis Gravitaxis (or ''geotaxis'') is a form of taxis characterized by the directional movement of an organism in response to gravity. Gravitaxis is one of the many forms of taxis. It is characterized by the movement of an organism in response to gravita ...
(known historically as geotaxis) is the directional movement (along the vector of gravity) to the center of gravity. The planktonic larvae of a king crab, ''
Lithodes aequispinus ''Lithodes aequispinus'', the golden king crab, also known as the brown king crab, is a king crab species native to the North Pacific. Golden king crabs are primarily found in the Aleutian Islands and waters nearer to Alaska and British Columbia; ...
'', combine positive phototaxis (movement towards the light) and negative gravitaxis (upward movement). Also the larvae of a polychaete, '' 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. Both positive and negative gravitaxes are found in a variety of
protozoa Protozoa (singular: protozoan or protozoon; alternative plural: protozoans) are a group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic tissues and debris. Histo ...
ns (''e.g.'', '' Loxodes'', '' Remanella'' and '' Paramecium''). * Magnetotaxis is, strictly speaking, the ability to sense a
magnetic field A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...
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's magnetic field. In this case, the "behaviour" has nothing to do with sensation and the bacteria are more accurately described as "magnetic bacteria". * Pharotaxis is the movement to a specific location in response to learned or conditioned stimuli, or navigation by means of landmarks. * Phonotaxis is the movement of an organism in response to sound. * Phototaxis is the movement of an organism in response to light: that is, the response to variation in light intensity and direction. Negative phototaxis, or movement away from a light source, is demonstrated in some insects, such as cockroaches. Positive phototaxis, or movement towards a light source, is advantageous for phototrophic organisms as they can orient themselves most efficiently to receive light for photosynthesis. Many
phytoflagellate A flagellate is a cell or organism with one or more whip-like appendages called flagella. The word ''flagellate'' also describes a particular construction (or level of organization) characteristic of many prokaryotes and eukaryotes and th ...
s, e.g. '' Euglena'', and the
chloroplast A chloroplast () is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in ...
s of higher plants positively phototactic, moving towards a light source. 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. *
Rheotaxis (Positive) Rheotaxis is a form of taxis seen in many aquatic organisms, 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 do ...
is a response to a 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 Thermotaxis is a behavior in which an organism directs its locomotion up or down a gradient of temperature. Lab research has determined that some slime molds and small nematodes (namely Meloidogyne incognita) can migrate along amazingly shallow t ...
is a migration along a gradient of temperature. Some slime molds and small
nematode The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-Parasitism, parasitic nematodes also known as eelworms. They are a diverse animal phylum inhab ...
s can migrate along amazingly small temperature gradients of less than 0.1 °C/cm. They apparently use this behaviour to move to an optimal level in soil. * 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).
Codling moth The codling moth (''Cydia pomonella'') is a member of the Lepidopteran family Tortricidae. They are major pests to agricultural crops, mainly fruits such as apples and pears. Because the larvae are not able to feed on leaves, they are highly d ...
larvae are believed to used thigmotactic sense to locate fruits to feed on. 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 (
vibrissae Vibrissae (; singular: vibrissa; ), more generally called Whiskers, are a type of stiff, functional hair used by mammals to sense their environment. These hairs are finely specialised for this purpose, whereas other types of hair are coarser ...
) 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.


Terminology derived from taxis direction

There are five types of taxes based on the movement of organisms. * ''Klinotaxis'' occurs in organisms with
receptor cell Sensory neurons, also known as afferent neurons, are neurons in the nervous system, that convert a specific type of stimulus, via their receptors, into action potentials or graded potentials. This process is called sensory transduction. The cel ...
s but no paired receptor organs. The cells for reception are located all over the body, particularly towards the anterior side. The organisms detect the stimuli by turning their head sideways and compare the intensity. When the intensity of stimuli is balanced equally from all sides then the organisms move in a straight line. The movement of
blowfly Blowfly or blow fly may refer to: * Calliphoridae, a family of flies * Blowfly (musician) Clarence Henry Reid (February 14, 1939 – January 17, 2016) was an American musician, songwriter and producer also known by the stage name and altern ...
and butterfly larvae clearly demonstrates klinotaxis. * ''Tropotaxis'' is displayed by organisms with paired receptor cells. When the stimuli coming from a source are balanced equally the organisms show movement. Because of this, animals are able to move sideways, unlike klinotaxis where the organisms can move only in a straight line. The movement of grayling butterflies and
fish lice The family Argulidae, whose members are commonly known as carp lice or fish lice, are parasitic crustaceans in the class Ichthyostraca. It is the only family in the monotypic subclass Branchiura and the order Arguloida, although a second family, ...
clearly demonstrates tropotaxis. * ''Telotaxis'' 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
bee Bees are winged insects closely related to wasps and ants, known for their roles in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyly, monophyletic lineage within the ...
s when they leave their
hive A hive may refer to a beehive, an enclosed structure in which some honey bee species live and raise their young. Hive or hives may also refer to: Arts * ''Hive'' (game), an abstract-strategy board game published in 2001 * "Hive" (song), a 201 ...
to look for food. They balance the stimuli from the sun as well as from flowers but land on the flower whose stimulus is most intense for them. * ''Menotaxis'' describes organisms' maintenance of a constant 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 to follow trails that organisms have left when travelling to or from their home.


See also

* Animal locomotion *
Haptotaxis Haptotaxis (from Greek ἅπτω (hapto, "touch, fasten") and τάξις (taxis, "arrangement, order")) is the directional motility or outgrowth of cells, e.g. in the case of axonal outgrowth, usually up a gradient of cellular adhesion sites or sub ...
*
Mechanotaxis Mechanotaxis refers to the directed movement of cell motility via mechanical cues (e.g., fluidic shear stress, substrate stiffness gradients, etc.). In response to fluidic shear stress, for example, cells have been shown to migrate in the direction ...
*
Optomotor response In behavioral biology, the optomotor response is an innate, orienting behavior evoked by whole-field visual motion and is common to fish and insects during locomotion, such as swimming, walking and flying. The optomotor response has algorithmic ...
* Tropism


References


External links


Host-plant finding by insects: orientation, sensory input and search patterns
{{Authority control Cell biology