Taxis and Kinesis

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Different types of movements can be seen in unicellular as well as multicellular organisms. The motives of these movements are also different. An organism may exhibit movement to find food, to seek shelter from heat or cold, to save itself from a predator, to find water supplies, or to search for prey, etc. 

Sometimes,  movements are forced by the environment in which the organism lives. The life of an organism is dependent on its relationship with the surroundings. Certain changes in the external environment can cause the organisms to show response in the form of a movement. Taxis and kinesis are examples of such movements.

In this article, we will discuss different types of taxis and kinesis, the differences between the two types of movements, and other associated concepts. So, keep reading.

Taxis

Before we talk about this particular movement that is called Taxis, it is imperative to talk about certain other things related to it. We must remember that it is the characteristic of each plant and animal to respond to a stimulus. However, animals respond quickly to the stimuli, while plants are slow in responding.

Let us first know the difference between a stimulus and a response.

Stimulus: A stimulus in the literal word means, a change in an environment. This change can be chemical or physical.  Few examples of stimulus are temperature, Water, Chemicals, gravity, and light.

Response: A response on the other hand is the unconscious or conscious reaction of the living beings to the stimulus. Most of the time this response is an involuntary activity that has the potential to benefit the organism.

What is TAXIS?

Now is the time to talk about the real deal. Whenever a living organism such as an animal responds to a stimulus in a way that ends up affecting its locomotion,  the response is called Taxis.

Animals are going to respond to a stimulus in two different ways and this means that there is going to be positive taxis on negative taxes.

Positive Taxis

Let’s say that there is a stimulus in an environment that is light. If the animal is moving towards the light, then it means that it is showing positive taxis.

We have seen houseflies in our house everywhere. Usually, houseflies or moths show a positive response to light. They are those organisms that exhibit positive taxis towards Light.

Negative Taxis

Not all the animals are going to show a positive response to a stimulus in the environment. Whenever there is light, mosquitoes tend to move away from it. They are those organisms that exhibit negative taxis.

Types of Taxis

The fun thing is there are many types of taxis based on the stimulus and now is the time to explore these types.

Geotaxis

When an animal is responding to gravity it is exhibiting Geotaxis. Not all the animals show a positive response to gravity, some exhibit negative responses as well. When it is Geotaxis, then we can take the example of amoeba. This tiny organism exhibits a positive response to gravity by dropping at the bottom of the container filled with water.

On the other hand, Paramecium shows a negative response to gravity. Along with Paramecium, houseflies or fruit flies always show a negative response to gravity.

Chemotaxis

When an organism is responding to the current of air or water it is called Chemotaxis. We can again take the example of Paramecium or Amoeba. In this scenario, Paramecium shows a positive response to the current air and water by trying to swim against the current.

On the other hand, Amoeba shows a negative response to the current of air or water. There are many kinds of fish there are also positively rheotactic and we can take the example of trout in this regard.

Thigmotaxis

Response to touch or contact is called Thigmotaxis. If we try to talk about Paramecium in this regard, then it shows a strange behavior in terms of Thigmotaxis. Let’s say, that it is swimming slowly and coming in contact with an object like plant stem or algae. On coming in contact with these objects, Paramecium will stay very quiet. On the other hand, if we talk about another scenario where the interior of Paramecium is touching a solid object, it will exhibit strong avoiding reactions.

Phototaxis

When an organism is responding to a stimulus of light, it is exhibiting Phototaxis. Euglena is a beautiful organism and it always moves toward the source of light thus exhibits positive Phototaxis. On the other hand, cockroaches, silverfish, slugs, and earthworms will always try to move away from the source of light and will exhibit negative Phototaxis.

Paramecium and Amoeba like staying in complete darkness and they avoid sunlight, but both of these organisms respond positively to normal or weak light.

Thermotaxis

Whenever the animal will respond to the stimulus of temperature it will be called Thermotaxis.  When it comes to animals then they like thriving at an optimum temperature that ranges between 20 to 25 degrees centigrade.

When the temperature is optimum then the organisms show a positive response towards it. Amoeba and Paramecium show positive Thermotaxis in the temperature that ranges between 20 to 25 degrees centigrade. On the other hand, if the temperature is higher or lower than the optimum temperature then the organisms will show negative Thermotaxis.

Chemotaxis

Animals showing response to anything related to chemicals is called Chemotaxis. Most of the organisms show a negative response to chemicals. When it comes to mosquitoes or Amoeba, then these organisms are always going to show a negative response to strong solutions of alkalis, acids, or sugars.

In most of the scenarios Paramecium shows a positive response to weak acid solutions, however, its response to a strong salt solution will always be negative.

When there are chemicals then the animals are likely to show negative chemotaxis more than positive.

Chemotaxis in Humans

An ideal example of chemotaxis in the human body is seen during the process of information. Any injury to the tissue releases certain chemotactic factors such as chemokines. These factors cause the white blood cells and other components of the defense system to leave the bloodstream and move towards the site of injury. This is essential to treat the infection, fight it as soon as it occurs, and limit it to the site of origin.

Another example of chemotaxis is seen during bleeding. When a blood vessel is injured and the blood begins to bleed, the injured tissue releases chemicals to attract components of the coagulation system at the site of bleeding. It helps to limit bleeding and form a blood clot immediately.

Electro taxis

The movement of an organism in response to an electric current is called Electro taxis or galvanotaxis. Animals’ response to Electro taxis is mostly negative, however, in some situations, Paramecium shows a positive response when exposed to weak electric current.

Kinesis

In Biology taxis and Kinesis go hand in hand. All the organisms in the world exhibit different responses to different stimuli. When the response is directional it is called a Taxis movement and when the response is non-directional then it is called the Kinesis movement.

To understand Kinesis more closely, it is imperative to talk about a stimulus and a response.

Stimulus

A stimulus is an object in the environment that has the capability of eliciting responses from organisms. This stimulus can be

  • Light
  • Water
  • Temperature
  • Gravity
  • Electricity
  • Chemicals

And much more.

Response

The response is the reaction of organisms to the stimulus. Animals and plants both show responses to a stimulus in different ways. While plants are a little slower in exhibiting response animals can be faster.

What is the Difference between the Taxis and Kinesis Movement?

There is a great difference between these two movements. In the Taxis movement, organisms either move towards the stimulus or away from it. In Taxis, movement is always directional. It is not rapid, haphazard, or random.

On the other hand, in Kinesis, the movement is always non-directional.

Let’s say that a fire is lit in someplace. Fire is a form of light energy and due to its intensity, the movement of the organism is going to be haphazard and rapid.

In the scenario of a fire, organisms are not going to move towards or away from the fire, rather in this scenario, the organisms will try to run away from the fire in a haphazard and random manner.

The movement in kinesis is always non-directional and we cannot say where the organisms must be going. In some cases, they will keep moving until they find their comfort zone.

Slow and Quick Movement in Kinesis

While there is positive or negative movement in taxis, there is a slow or quick movement in kinesis.

Amoeba and Paramecium like staying in the dark. When these organisms see the light intensity, they try to run away from it haphazardly and randomly.

If the light intensity is too much their pace will be quicker. On the other hand, if the light intensity is weak then they will move slowly away from it.

What are the two basic types of Kinesis?

There are two basic types of Kinesis Movements and these are

Orthokinesis

Orthokinesis is all about the speed of the organism in relation to the intensity of the stimulus.

We can take the example of woodlice here. This particular organism likes staying in a humid environment. When it feels that the environment is appropriate and humid then It stays stationary for a considerable period of time. We can also talk about Paramecium. This organism like staying in a darker environment. The darker there is, the more there are chances that Paramecium is likely to stay there for hours to come.

On the other hand, we can also take the example of cockroaches. They do not like the intensity of light. When cockroaches feel that they are in a room full of light, they try to run away from it at full speed until they find their comfort zone where there is weak or no light at all.

Klinokinesis

It is another type of Kinesis where the rate of turning or frequency is directly proportional to stimulus intensity.

For this particular type, we can take the example of flatworm. This particular organism likes staying in the dark and when it sees that there is an intensity of light, it tries to turn away from it rapidly and haphazardly. Flatworms will keep on turning away from the intensity of light until they find the comfort zone.

We can say the same about Amoeba that it likes turning away from light as well more frequently.

Why organisms exhibit Kinesis Movement?

Organisms exhibit kinesis movement because God has created them this way. They turn away from predators or dangerous situations. An intensity in any stimulus for organisms means that there can be a possible danger or predator lurking in the dark.

For this reason, whenever organisms see that there is an intensity of a stimulus, they try to find a comfort zone to hide. Kinesis movement is always non-directional, and the organism will keep moving until it finds the comfort zone.

Once the organism is in the comfort zone then it’s movement will slow down because it will feel itself to be safe and secure from the possible predators or dangers in the environment.

Summary

Taxis and kinesis are the two types of movements shown by organisms in response to different stimuli.

Taxis is a directional movement of an organism or cell towards or away from a stimulus.

  • Positive taxis is a movement towards the stimulus
  • Negative taxis is a movement away from the stimulus

Several stimuli can provoke the tactic movement of cells or organisms.

  • Gravity causes geotaxis
  • Light causes chemotaxis
  • Chemical substances cause chemotaxis
  • Touch stimulus causes thigmotaxis
  • Heat causes thermotaxis
  • Electric charge or current causes electro taxis

Kinesis is the random and haphazard movement of organisms due to a stimulus. It is a non-directional movement that can be slow or fast.

Two types of kinesis are

  • Orthokinesis
  • Klinokinesis

References

  1. A.N. Gorban,N. Çabukoǧlu, Basic model of purposeful kinesisEcological Complexity, Volume 33, January 2018, Pages 75-83.
  2. Kendeigh, S. C. (1961). Animal Ecology. Prentice-Hall, Inc., Englewood Cliffs, N.J. pp. 468 pp.
  3. Dusenbery, David B. (2009). Living at Micro Scale, Ch. 14. Harvard University Press, Cambridge, Massachusetts ISBN 978-0-674-03116-6.
  4. Martin, E.A., ed. (1983). Macmillan Dictionary of Life Sciences (2nd ed.). London: Macmillan Press. p. 362. ISBN 0-333-34867-2.
  5. Kennedy, J. S.; Marsh, D. (1974). “Pheromone-regulated anemotaxis in flying moths”. Science. 184 (4140): 999–1001. doi:10.1126/science.184.4140.999PMID 4826172.