Locomotion in Microorganisms: All living organisms show some type of movement. Animals, however, move morely. Animals possess definite organs for locomotion. From the tiny organisms that are not visible to our naked eyes and up to the larger living organisms, different locomotory organs are present to help in locomotion. Have you ever wondered how microorganisms like bacteria, Paramecium, Amoeba, Euglena, etc., move from one place to another?

Do they have any special locomotory organs for their movement? Pseudopodia, cilia, flagella, etc., are a few examples of locomotory organs of few microorganisms that help in locomotion or movement. Movement is the change in position of only a part of the body.

What is Locomotion?

Locomotion is the act of movement of the entire body of the organisms from one place to another. Locomotion involves the movement of the whole body, as in walking, running, swimming or flying.

Why is Locomotion Necessary?

Locomotion helps the organisms in several ways.

1. It helps the animals to move in search of food, water and shelter.
2. It also helps them to shift from an unfavourable environment to a favourable one.
3. It helps the animals to move away from their predators.
4. Animals move about to find their partner or mate for reproduction.
5. Animals also move to safe areas to lay eggs or give birth to young ones and bring them up.

Locomotory Organs in Microorganisms

The organs that help in the movement of the body from one place to another are called locomotory organs.

1. Flagella: The flagellum is a hair-like appendage. It originates from a basal body. The structural protein is called flagellin. The internal structure of the flagellum consists of a 9+2 fibrillar arrangement.
Example: Euglena

Fig: Flagella

2. Pseudopodia: Pseudopodia is the temporary outgrowth of protoplasm. It is considered to be the most primitive type of animal locomotory organ. These are formed from any part of the body. The process of formation of pseudopodia was explained by Sol-gel Theory or Change of Viscosity Theory.
Example: Amoeba possesses pseudopodia.

Fig: Pseudopodia

3. Cilia: Cilia are slender, small, hair-like outgrowths of the cell membrane. These are small compared to flagella. The cilia move together just like the oars of a boat in a coordinating manner, causing the movement of either the cell or the surrounding fluid. It is covered with a plasma membrane.
Example: Paramecium possesses cilia.

Fig: Cilia

4. Tentacles: Tentacles are the long flexible, slender, elongated organs on the head of microorganisms. These might be one or more in number.
Example: Hydra

Fig: Tentacles

Types of Locomotion in Microorganisms

1. Amoeboid Movement: Unicellular animals like Amoeba move using pseudopodia. The movement of the Amoeba using its pseudopodia is called amoeboid movement or amoeboid locomotion.
2. Flagellar Movement: When microorganisms tend to move their body with the help of the locomotory organ flagellum, it is called flagellar movement. Bacteria show this type of movement.
3. Ciliary Movement: Some microorganisms have hair-like structures on their body as a locomotory organ called cilia. The cilia help to move by repeatedly lashing out cilia that help to move forward and backwards. Movement by cilia is called ciliary movement or ciliary locomotion.
4. Looping Movement: Looping is a mode of locomotion in a few microorganisms. The body is fixed to any hard basal or substratum and bends its body from its standing position, and attaches to the substratum with the help of tentacles present on the other end of the body. It loops, moves forward with its basal part and thens up the attachment and moves its tentacles upwards to stand straight. This type of movement is seen in Hydra.
5. Somersault Movement: Somersault is another type of movement that helps microorganisms to move from one place to another. This type of movement is seen in Hydra.

Locomotion in Different Microbes

1. Locomotion in Amoeba: Amoeba shift from one place to another place very slowly, and their locomotion is irregular because of false feet. Amoeba moves with the help of a finger-like outgrowth known as pseudopodium. Pseudopodia are formed when the actin polymerization is activated.

It is a temporary locomotory organ formed in the cytoplasm when the actin filament that forms in the cytoplasm pushes the cell membrane that results in temporary projections called pseudopodia. When new pseudopodia are formed on one side of the body, the old pseudopodia disappear. In this way, Amoeba moves by rolling.

Fig: Locomotion in Amoeba

2. Locomotion in Paramecium: Paramecium has hundreds of small fine hairs called cilia. It can move backwards and forwards. While moving forward, cilia strongly move from anterior to posterior. Coordinated movement of cilia helps the movement of the organism.

Fig: Locomotion in Paramecium

3. Locomotion in Bacteria: Bacteria has three types of locomotion mainly- Flagellar, Spirochaetal and Gliding movement. Flagella is a single long hair-like structure. Movement takes place by the whip-like action of the flagellum. Flagella are formed from specialized groupings of microtubules. If the protrusions are short and numerous, they are termed cilia. If they are longer and less numerous, they are termed flagella.

Fig: Locomotion in Bacteria

4. Locomotion in Hydra: Hydra moves from one place to another with the help of tentacles. The mouth is surrounded by a number of tubular structures called tentacles. Movement of hydra is caused by contraction and relaxation of body cells, while locomotion is caused by looping and somersault.

(a) Looping Movement: In looping movement, the foot remains attached, and the body bends over till the tentacles touch or gets attached to the surface. The foot releases its hold and is placed close to the tentacles. The tentacles release their hold and the organisms, such as Hydra, straighten themselves.

Fig: Looping Movement in Hydra

(b) Somersault Movement: The body bends till the tentacles touch the surface. The foot releases itself from the surface, and the body becomes straight. Hydra, in this situation, stands on its tentacles. The process is repeated, and the animal moves forward.

Fig: Somersault Movement in Hydra

Summary

We see different animals and small creatures that walk, run, crawl, etc., in our surroundings daily. There are few creatures that are small and tiny which are not visible to our naked eyes. They are microscopic in nature; hence they are called microorganisms. In the above article, we came to know about how microorganisms move from one place to another place. The locomotory organs are unique and special in the case of microorganisms. They do not use legs, wings, or feet for their locomotion.

Flagella, cilia, tentacles, etc., are few examples of locomotory organs in microorganisms. Few microorganisms like hydra move from one place to another place by looping movement or somersault movement.

Frequently Asked Questions (FAQs)

Q.1. What is the most common method of reproduction in bacteria?
Ans: Binary fission is the most common method of reproduction in bacteria.

Q.2. What do microorganisms use for movement?
Ans: Microorganisms show the characteristics of the movement. They use locomotory organs such as flagella, cilia, pili, etc.

Q.3. How do microorganisms swim?
Ans: Microorganisms swim through aqueous media by rotating flagella. The thin, long filaments are driven at their base by rotary motors.

Q.4. How do bacteria move?
Ans: Bacteria move from one place to another by using a structure called the flagellum.

Q.5. How fast do bacteria move?
Ans: Bacteria can move at the speed of 2 microns per second to 200 microns per second.

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