PHYLUM: PROTOZOA Methods of Locomotion: 2. Swimming By: AAKRITI
SWIMMING MOVEMENT . Swimming locomotion in protozoans is caused by the . Flagella bring about the movement of some parasites in . As the movement in this case is caused by the beating . Depending on the structure involved swimming flagella and cilia. the body fluids of the hosts. flagella and cilia are also known as undulipodia. movement can be of two types namely, Flagellar movement Ciliary movement
Flagellar movement . A flagellum pushes the fluid medium at right angles to the surface of its attachment, by its bending movement. The bending movement of flagellum is made by the sliding of microtubules past each other with the help of dynein arms. The dynein arms show a complex cycle of movement with the energy provided by ATP. . These dynein arms attach to the outer microtubule of an adjacent doublet and pull the neighboring doublet.
Microtubules In Cilia And Flagella outer dynein arm radial spoke inner sheath central singlet nexin microtubule plasma membrane inner dynein arm A microtubule B microtubule outer doublet microtubule 100 nm 9+2 arrangement of microtubules; outer doublets Cross-linking proteins . Ciliary dynein
. As the result the doublets slide past each other in opposite direction. . The arms release and attach a little farther on the adjacent doublet and again pull the neighboring doublet. The doublets of the flagellum are physically held in place by the radial spokes and thus the doublets cannot slide past much and their sliding is limited by the radial spokes. Instead the doublets can curve causing a bend in the flagellum and this bending has an important role in the flagellar movement.
* Flagellum shows the following movements, Undulation movement: . Undulation from the base to the tip causes pushing force and pushes the organism backwards. Similarly undulation from the tip to the base causes pulling force and causes the organism to pull forward Also when the flagellum ends to one side and shows wave like movement from base to tip the organism moves in laterally in opposite direction. . Finally when the undulation is spiral, it causes rotatiorn of the organism in the opposite direction and this is called as gyration.
Pushing force Pulling force Undulations Direction of movement Tip to base Base to tip UNDULAR MOVEMENT OF FLAGELLUM
Sidewise lash movement: The flagellar movement of many organisms is a paddle-like beat or sidewise lash consisting of strokes namely effective stroke and recovery stroke. Effective stroke - During effective stroke the flagellum becomes rigid and starts bending against the water This beating in water at right angles to the longitudinal axis of the body causes the organism to move forward. Recovery stroke - During recovery stroke, the flagellum becomes comparatively soft and will be less resistant to the water. This helps the flagellum move backwards and then to the original position.
Direction of Locomotion Propulsion of water Effective stroke Recovery stroke
Simple conical gyration movement: In this kind of movement the flagellum turns likea screw. This propelling action pulls the organism forward through the water with a spiral rotation around the axis of movement and gyration on its own
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