Kinesis, like a taxis or tropism, is a movement or activity of a cell or an organism in response to a stimulus. 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." In this case, a fast movement 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 woodlice in relation to humidity. With increased humidity there is an increase in the percentage time that the woodlice will remain stationary. Klinokinesis: in which the frequency or rate of turning is proportional to stimulus intensity. For example the behaviour of the flatworm which turns more frequently in response to increasing light thus ensuring that it spends more time in dark areas.
The kinesis strategy controlled by the locally and instantly evaluated well-being 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 minimalreaction-diffusion model of kinesis can be written as follows: For each population in the biological community, where: is the population density of ith species, represents the abiotic characteristics of the living conditions, is the reproduction coefficient, which depends on all and on s, is the equilibrium diffusion coefficient. The coefficient 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.
