Locomotion | Locomotion In Euglena |

LOCOMOTION.

Locomotion In Euglena

This characteristic movement of euglena is called the euglenoid movement.

Two structures take part in the locomotion of Euglena:

⧫ Flagella:

Euglena moves with the help of flagellum. The flagellum is present at its anterior end of the body and it pulls the organism forward. Euglena whips its flagellum backward and its body moves forward. However, when flagellum moves forward the Euglena does not move backward. The wave of activity is produced by itself, and they pass in a spiral fashion from its base to its tip. These waves increase the amplitude and velocity of euglena. The body of Euglena produces the activity note in the flagellum and the flagellum rotates forward about its axis.

⧫ Myonemes:

Euglena can change its shape with the help of active contractile myonemes. These myonemes run along the length of its body. The contraction of myonemes changes the shape and direction of euglena. First. the body becomes short and wider at the anterior end than in the middle and later at the posterior end.

Locomotion in Paramecium:

Paramecium moves with the help of cilia. This is called the ciliary movement All the cilia do not move simultaneously. A bunch of cilia moves in a progressive wave-like manner at a time. The wave starts at the anterior end and progresses in the backward.

Structure of Cilia:

Cilia are short, fine thread-like extensions ( membrane. The length of cilia ranges from many microns to many hundred microns and the diameter varies from 0.1 to 0. 5. u. A cilium consists of nine peripheralS 09, LS Jlg ou) double fibrils. These fibrils give the appearance of the 8-shape figure. The cilium also has two central smaller fibrils. All these fibrils run longitudinally through the cilium These fibrils are covered by the extensions of the membrane.

Mechanism of contraction of cilia:
The exact mechanism of movement of cilia is not known, however, in 1955 Bradford suggested that simultaneous contraction or sliding of double fibrils take place in two groups one after the other. This contraction or sliding produces the movement of cilia.
(i). Effective stroke:
Five out of nine (5/9) double fibrils contract or slide simultaneously Thus the cilium bend or shorten. It is called an effective stroke.
(ii). Recovery stroke:
The four out of nine double fibril contract and cilium becomes straight. It is called a recovery stroke.

Paramecium swims against water due to bending and recovery strokes of the cilium. The ATP provides the energy for the movement of cilia. The enzyme present in the cilia breaks up ATP to release energy. The action of the cilia is coordinated. So all the cilia beat together in a sequence and propel the animal in one direction.

Locomotion in Amoeba:

In Amoeba movement takes place by means of pseudopodia. The pseudopodia are finger-like projections. They are produced in the direction of movement. The cytoplasm flows in the pseudopodia and the body moves in that direction. The exact mechanism of the formation of pseudopodia is still not known.

Locomotion in Earthworm

Earthworm shows accordion (musical instrument) like movement. In this case,

the setae and muscles both take part. There are two steps in the forward movement of the earthworm.

➤ Firstly, the earthworm becomes long and thin. The setae present on the lower side of the anterior end come out. The setae anchor and hold this end firmly. The longitudinal muscles now contract and circular muscles relax. So the body shortens thus pulling this portion forward.

➤ The setae of the posterior end come out and fix the animal on the ground Now circular muscles contract and longitudinal muscles relax. Thus the body becomes thin and long. In this way, earthworm moves from one place to the other.

Locomotion in StarFish

Starfish moves with the help of tube feet. The tube feet are present on both sides of the radial canal. These tube feet extend up to the tip of the arm. The tube feet extend when water is pumped into them. Then they fix themselves by the suction cup with some object. Later on, they shorten and pull the body in this direction. In this way starfish move in any direction. Arms of the starfish also help in swimming.