What is the Difference Between Taxis and Kinesis

The main difference between taxis and kinesis is that taxis is the directed movement of living organisms in response to a particular stimulus whereas kinesis is the random movement of living organisms. Furthermore, aerotaxis, magnetotaxis, phototaxis, and chemotaxis are the example movements of taxis while orthokinesis and klinokinesis are the two types of kinesis.

Taxis and kinesis are innate behavioral responses of living organisms. They are two types of motions, which occur in response to external environmental stimuli.

Key Areas Covered

1. What is Taxis
     – Definition, Types, Importance
2. What is Kinesis
     – Definition, Types, Importance
3. What are the Similarities Between Taxis and Kinesis
    – Outline of Common Features
4. What is the Difference Between Taxis and Kinesis
    – Comparison of Key Differences

Key Terms

Directional Movement, Innate Behavioral Responses, Kinesis, Random Movement, Taxis

What is Taxis

Taxis is the directional movement of living organisms. It occurs either towards or away from a particular stimulus. Positive taxis refers to the movement of the organism towards the stimuli while negative taxis refers to the movement of an organism away from the stimuli. The attraction of fruit flies to the light is an example of a positive taxis while climbing up of fruit flies in a chamber against gravity is an example of negative taxis.

Figure 1: Oxygen Dependency of Different Types of Bacteria
1. Obligate aerobic bacteria gather at the top of the test tube in order to absorb the maximal amount of oxygen, 2. Obligate anaerobic bacteria gather at the bottom to avoid oxygen, 3. Facultative bacteria gather mostly at the top since aerobic respiration is advantageous (ie, energetically favorable); but as lack of oxygen does not hurt them, they can be found all along the test tube, 4. Microaerophiles gather at the upper part of the test tube, but not at the top. They require oxygen, but at a lower concentration, 5. Aerotolerant bacteria are not affected at all by oxygen, and they are evenly spread along the test tube.

In addition, based on the type of stimuli, different types of taxis can be seen in organisms. Some examples of taxis are aerotaxis (stimulation by oxygen), barotaxis (stimulation by pressure), chemotaxis (stimulation by chemicals), hydrotaxis (stimulation by moisture), magnetotaxis (stimulation by a magnetic field), phototaxis (stimulation by light), thermotaxis (stimulation by temperature), etc.

What is Kinesis

Kinesis is the unidirectional or random movement of organisms in response to a stimulus. Also, it can refer to the change in the activity level of an organism depending on the intensity of a stimulus. Since it generates random movements, kinesis is neither positive nor negative. The random movement of a group of cockroaches in response to the high-intensity light is an example of kinesis. Other types of stimuli generating kinesis can be gas exposure, ambient temperature, etc.

Figure 2: Woodlouse Activity Decreases as Humidity Increases

Furthermore, depending on the comfort zone of each organism, the rate of kinesis can differ. Therefore, fast movement indicates that the organism is searching for a comfort zone while slow movement indicates that the organism has already found its comfort zone. Also, orthokinesis and klinokinesis are the two types of kinesis. Orthokinesis is the dependence of the speed of the movement upon the intensity of the stimulus and klinokinesis is the dependence of the rate of turning upon the intensity of the stimulus.

Similarities Between Taxis and Kinesis

• Taxis and kinesis are two types of innate behavioral responses of living organisms.
• The whole organism moves in both types of movement, not a part of the organism as in tropism.
• Also, both can be performed in response to a cue without prior experience.
• Generally, they occur in simple organisms.
• Besides, some external stimuli generating these movements are light, temperature, water, food, gravity, certain chemicals, etc.

Difference Between Taxis and Kinesis

Definition

Taxis refers to a motion or orientation of a cell, organism, or part in response to an external stimulus while kinesis refers to an undirected movement of a cell, organism, or part in response to an external stimulus. Thus, this is the main difference between taxis and kinesis.

The direction of the Movement

The direction of movement is a major difference between taxis and kinesis. Taxis is a directional movement which occurs towards (positive) or away from the stimuli (negative) while kinesis is a random movement.

Types

Aerotaxis, magnetotaxis, phototaxis, and chemotaxis are the example movements of taxis while orthokinesis and klinokinesis are the two types of kinesis. Hence, this is another difference between taxis and kinesis.

Conclusion

Taxis is the directional movement of a living organism in response to a particular stimulus. This type of movement occurs wither towards the stimuli or away from the stimuli. In comparison, kinesis is the random movement of organisms in response to a particular stimulus. Both types of movements are innate behavioral responses of mainly primitive organisms and they can be performed in response to a cue without prior experience. However, the main difference between taxis and kinesis is the direction of the movement.

References:

1. “Innate Behaviors.” Khan Academy, Khan Academy, Available Here.

Image Courtesy:

1. “Anaerobic” By Pixie – Own work (Public Domain) via Commons Wikimedia 
2. “Oniscus asellus – male front 2 (aka)” By André Karwath aka Aka – Own work (CC BY-SA 2.5) via Commons Wikimedia