Human anatomy is complex, and thus there are several reactions within the bodies of these multicellular organisms; several movements are not visible or might be taken as usual, but they are not noticed much.
Stimulus plays an important role in creating such movements; stimulus is a physiological phenomenon that detects changes in the physical or chemical structure of an organism’s external or internal environment.
They also affect the movements in the animal body; for example, when the sunlight feels too warm on the body, the animal tends to move in the direction of shade or a cool environment.
The person might not notice the movement but it took an internal reaction to produce this response. Likewise, there are other responses for stimulus. There are generally two types of motions when responding to a stimulus: taxis and kinesis.
- Taxis are a type of movement in response to a directional stimulus, such as light or chemicals, where an organism moves towards or away from the source of the stimulus; kinesis is a non-directional movement in response to a stimulus, where the organism moves more or less depending on the intensity of the stimulus.
- Taxis are a more precise and directed response, allowing organisms to find food, mates, or suitable environments; kinesis is a more generalized response, allowing organisms to avoid unfavourable conditions or locate resources.
- Taxis can be positive (towards the stimulus) or negative (away from the stimulus); kinesis can be orthokinesis (movement speed varies with the stimulus intensity) or klinokinesis (turning rate varies with the stimulus intensity).
Taxis vs. Kinesis
Taxis is a directional response of an organism towards or away from a stimulus, which can be phototaxis or chemotaxis, depending on the stimulus. Kinesis is a non-directional response of an organism to a stimulus, resulting in a change in the rate of movement or activity level.
|Parameters of Comparison||Taxis||Kinesis|
|Type of movement||Specific direction||No specific direction|
|Direction of movement||Towards or away from the source of stimulus.||Random direction from a source of stimulus.|
|Types||Phototaxis, aerotaxis, geotaxis, thigmotaxis, etc..||Orthokinesis and klinokinesis|
|Rate of dependency on stimulus||Less dependent on stimulus intensity.||More dependent stimulus intensity.|
|Examples||Euglena or humans, etc..||Lice or beetle, etc.|
What is Taxis?
Taxis are the biological, behavioral response of a cell or an organism to an external stimulus, which may be towards or away from the source of stimulus. The attraction and repulsion from the source of a stimulus depend upon the organism’s brain.
There are several types of taxis identified; aerotaxis, anemotaxis, barotaxis, chemotaxis, durotaxis, galvanotaxis, gravitaxis, hydrotaxis, magnetotaxis, phonotaxis, phototaxis, rheotaxis, thermotaxis, thigmotaxis, etc..
In taxis like thermotaxis, the animal would respond to the temperature stimulus; in phototaxis, the animal would respond to light stimulus; in chemotaxis, the animal would respond to any chemical stimulus; in thigmotaxis, the animal would respond to touch or contact, and so on.
Two types of movements in taxis are positive and negative.
Positive movement is said when the movement is towards the source of stimulus, and negative is when the movement is away from the source. The response is common in every animal, but still, some exceptions exist.
Normal animal behavior depends on their surroundings; thus, the animal brain responds differently in every situation and stimulus. The behavior also varies from animal to animal. Taxis’ movements are present in animal behavior and can also be seen in regular life.
Some examples of taxis are; euglena moving towards the light source, which can be classified as phototaxis, any person touching something warm will suddenly move his hand backward, which can be classified as thigmotaxis, and so on.
These movements will occur either towards the stimulus source or away from it.
What is Kinesis?
Kinesis is a biological behaviour or activity of animals responding to stimulus but unlike taxis, kinesis does not have any specific direction movement.
The difference between taxes in kinases lives in the type of movement; in kinesis, the movement is random, which means it does not have any particular direction, like negative or positive or toward or away; the response to a stimulus can produce kinesis in any direction randomly.
There are two types of kinesis; those are; orthokinesis and klinokinesis, wherein orthokinesis involves the dependence of stimulus to the movement of the individual, and klinokinesis involves frequency or rate of turning proportional to the intensity of the stimulus.
The stimulus can be of several types within an environment like temperature, sun, air, water, etc.. everything produces some reaction in the animal body to which they respond accordingly. KInesis is somewhat related or dependent on taxis.
Some examples of kinesis are; lice move to turn far from frequently in the warm area, which means they tend to spend more time in the warmer region, which is not a directional response, another example is beetle moving faster in areas of light but this is not directional response as some beetles move completely in opposite directions.
Main Differences Between Taxis and Kinesis
- In taxis, the direction of response is specific. On the other hand, in kinesis, the response direction is not specific; rather, it is random.
- Taxis have several types, like phototaxis, thigmotaxis, geotaxis, chemotaxis, aerotaxis, etc. On the other hand, kinesis is of two types: orthokinesis and klinokinesis.
- In taxis, movement occurs towards or away but in kinesis, there is no particular direction of movement.
- The rate of taxis is less correlated with the intensity of the stimulus. On the other hand, the rate of kinesis is dependent on the intensity of the stimulus.
- Some examples of taxis are; the movement of euglena or humans in response to stimulus, and a few examples of kinesis are; lice or beetles moving faster but not in any particular direction.
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Piyush Yadav has spent the past 25 years working as a physicist in the local community. He is a physicist passionate about making science more accessible to our readers. He holds a BSc in Natural Sciences and Post Graduate Diploma in Environmental Science. You can read more about him on his bio page.