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Kinesis, like a taxis or tropism, is a movement or activity of a cell or an organism in response to a stimulus (such as
gas exposure Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma). A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or co ...
, light intensity or ambient temperature). Unlike taxis, the response to the stimulus provided is non-directional. The animal does not move toward or away from the stimulus but moves at either a slow or fast rate depending on its "
comfort zone comfort zone is a psychological state in which things feel familiar to a person and they are at ease and (perceive they are) in control of their environment, experiencing low levels of anxiety and stress. Bardwick defines the term as "a beha ...
." In this case, a fast movement (non-random) means that the animal is searching for its comfort zone while a slow movement indicates that it has found it.


Types

There are two main types of kineses, both resulting in aggregations. However, the stimulus does not act to attract or repel individuals. Orthokinesis: in which the speed of movement of the individual is dependent upon the stimulus intensity. For example, the locomotion of the
collembola Springtails (Collembola) form the largest of the three lineages of modern hexapods that are no longer considered insects (the other two are the Protura and Diplura). Although the three orders are sometimes grouped together in a class called Ent ...
, '' Orchesella cincta'', in relation to water. With increased water saturation in the soil there is an increase in the direction of its movement towards the aimed place. Klinokinesis: in which the frequency or rate of turning is proportional to stimulus intensity. For example the behaviour of the
flatworm The flatworms, flat worms, Platyhelminthes, or platyhelminths (from the Greek πλατύ, ''platy'', meaning "flat" and ἕλμινς (root: ἑλμινθ-), ''helminth-'', meaning "worm") are a phylum of relatively simple bilaterian, unsegment ...
('' Dendrocoelum lacteum'') which turns more frequently in response to increasing light thus ensuring that it spends more time in dark areas.


Basic model of kinesis

The kinesis strategy controlled by the locally and instantly evaluated well-being ( fitness) can be described in simple words: Animals stay longer in good conditions and leave bad conditions more quickly. If the well-being is measured by the local reproduction coefficient then the minimal reaction-diffusion model of kinesis can be written as follows: A.N. Gorban,N. Çabukoǧlu
Basic model of purposeful kinesisEcological Complexity
Volume 33, January 2018, Pages 75-83.
For each population in the biological community, \partial_t u_ i ( x,t) = D_ \nabla \left(e ^ \nabla u_i \right)+r_i (u_1,\ldots,u_k,s) u_i, where: u_i is the population density of ''i''th species, s represents the abiotic characteristics of the living conditions (can be multidimensional), r_i is the reproduction coefficient, which depends on all u_i and on ''s'', D_>0 is the equilibrium diffusion coefficient (defined for equilibrium r_i=0). The coefficient \alpha_i>0 characterises dependence of the diffusion coefficient on the reproduction coefficient. The models of kinesis were tested with typical situations. It was demonstrated that kinesis is beneficial for assimilation of both patches and fluctuations of food distribution. Kinesis may delay invasion and spreading of species with the
Allee effect The Allee effect is a phenomenon in biology characterized by a correlation between population size or density and the mean individual fitness (often measured as ''per capita'' population growth rate) of a population or species. History and backgr ...
.


See also

*
Brownian motion Brownian motion, or pedesis (from grc, πήδησις "leaping"), is the random motion of particles suspended in a medium (a liquid or a gas). This pattern of motion typically consists of random fluctuations in a particle's position ins ...
*
Chemokinesis Chemokinesis is chemically prompted kinesis, a motile response of unicellular prokaryotic or eukaryotic organisms to chemicals that cause the cell to make some kind of change in their migratory/swimming behaviour. Changes involve an increase or de ...
*
Cranial kinesis Cranial kinesis is the term for significant movement of skull bones relative to each other in addition to movement at the joint between the upper and lower jaw. It is usually taken to mean relative movement between the upper jaw and the braincase. ...
*
Cytokinesis Cytokinesis () is the part of the cell division process during which the cytoplasm of a single eukaryotic cell divides into two daughter cells. Cytoplasmic division begins during or after the late stages of nuclear division in mitosis and meios ...
* Diffusion *
Nastic movements Nastic movements are non-directional responses to stimuli (e.g. temperature, humidity, light irradiance), and are usually associated with plants. The movement can be due to changes in turgor. Decrease in turgor pressure causes shrinkage while ...
*
Photokinesis Photokinesis is a change in the velocity of movement of an organism as a result of changes in light intensity. The alteration in speed is independent of the direction from which the light is shining. Photokinesis is described as positive if the vel ...
* Rapid plant movement


References

*Kendeigh, S. Charles. 1961. ''Animal Ecology''. Prentice-Hall, Inc., Englewood Cliffs, N.J., 468 p.


External links

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Host-plant finding by insects: orientation, sensory input and search patterns
Physiology Perception Signal transduction