Kinesis vs Taxis
Difference between kinesis and taxis shows you how organisms respond to external stimulus. In fact, kinesis and taxis are two kinds of movements shown by organisms especially by invertebrates in response to an external stimulus. Main difference between the two types is whether the movement is directional or non-directional according to the direction of the intensity of the stimulus.
What is Kinesis?
Kinesis is described as non-directional response by organisms to a stimulus. Organism will not move towards or away from the location of the stimulus, instead it will show random movements to get into a comfortable place. There are two categories of kinases: Orthokinesis and Klinokinesis. In Orthokinesis, the speed of the movement is changed with the intensity of the stimulus. In Klinokinesis, the rate of the movement is proportional to the intensity of the stimulus.
Here are some examples.
• A woodlouse will move about a drier surface rapidly in search for more humid place.
• Thigmonasty (touch-induced movements) of Mimosa leaves vary with the intensity of stimuli such as touch, heat, or rapid cool.
A woodlouse will move about a drier surface rapidly in search for more humid place
What is Taxis?
Taxis is defined as the directional locomotion of an organism in response to a stimulus. Organism will move towards or away from the stimulus. So, there are basically two directions; “towards,” a positive taxis and “away,” a negative taxis. According to the type of stimulus, taxis can be categorized as phototaxis (stimulus is light), chemotaxis (stimulus is a chemical compound), aerotaxis (stimulus is oxygen), etc. Depending on the type of sensory organ, taxis is subdivided into klinotaxis, tropotaxis, and telotaxis. In klinotaxis, organisms continuously search for the direction of the stimulus. In tropotaxis, bilateral sense organs such as antennae will be used to determine the direction of the stimulus. In telotaxis, single organ is enough to determine the direction of the stimulus.
Here are some examples.
• Single cell green algae Chlamydomonas move towards the light from low light intensity to high intensity. This movement can be considered as positive phototaxis.
• In multicellular organisms, movement of sperm towards the egg cell can also be considered as a positive chemotaxis.
Movement of sperm towards the egg cell can also be considered as a positive chemotaxis
What is the difference between Kinesis and Taxis?
● Both kinesis and taxis are types of movements in response to a stimulus.
● Direction of kinesis is not correlated with the direction of stimulus whereas it is correlated in taxis.
● Rate of the kinesis is dependent on the intensity of the stimulus whereas the taxis rate is less correlated with the intensity of the stimulus.
● Kinesis is always random whereas taxis is always directed.
Images Courtesy:
- Woodlouse by Stemonitis (CC BY 2.5_)
- Sperm by Gilberto Santa Rosa (CC BY 2.0)
