Kinesis (biology)



Kinesis, like a taxis or tropism, is a movement or activity of a cell or an organism in response to a stimulus. However, unlike taxis, the response to the stimulus provided (such as gas exposure, light intensity or ambient temperature) is non-directional.

The two main types of kineses include:

Orthokinesis: in which the speed of movement of the individual is dependent upon the intensity of the stimulus. Take, for example, the locomotion of a woodlice in relation to temperature. 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.

Cranialkinesis: some lizards possess the ability to change to change the skull formation. when the mouth opens during feeding, the quadrate rotates forward, the palato-maxillary unit is lifted and the occipital unit swings forward. During jaw closing, the inverse movements are observed; during crushing, the system is retracted beyond its resting position. The data gathered here indicate that the coupled kinesis (streptostyly + mesokinesis) is most prominently present during the capture and crushing cycles of feeding and is largely absent during late intraoral transport, swallowing, drinking and breathing. The electromyographic data indicate a consistent pattern of muscular activation, with the jaw opener and pterygoid protractor always active during the fast opening phase, and the jaw closers active during closing and crushing.

Both orthokinesis and klinokineses result in aggregations. However, the stimulus does not act to attract or repel individuals.

The same prefixes used with "taxis" can be applied to kineses; see also -kinesis.

Kinesis is an animal's non-directional response to a stimulus, for example humidity. 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(non random) means that the animal is searching for its comfort zone but a slow movement indicates that it has found it.