Locomotion System in Amoeba

Systematic position:-

  Phylum : Protozoa

  Class.   : Rhyzopodea

  Order.   :  Amoebida

  Genus.  : Amoeba

  Species:  Proteous

Locomotion:-

   Amoeba shows many characteristic amoeboid movement by the formation of finger like a temporary process called pseudopodia. These are broads and with rounded tips are called lobopodia, which formed as a result of flowing forward of cytoplasm. When moving, amoeba may put out several pseudopodium.

           Number of theories have been advocated to explain the mechanism involves in the formation of a pseudopodium.Some of them are described below-

Surface tension theory:-

  Berthowled explained that the amoeboid movement is due to a difference in the surface tension between the physical characteristics of body surface and substratum. According to this theory the amoeboid movement is comparable with the movement of a fluid globule like a mercury droplet. A pseudopodium is formed by an outflow of cytoplasm from the weak point where surface tension becomes reduced by external or internal factors.

Sol-Gel theory:-

  This theory first put forward by 'Hyman' and later supported by 'Pantin' and 'Mast' is the most widely acceptable view nowadays.

A single pseudopodia is formed, the ectoplasmic tube forces endoplasm forward

       

   According to this theory the cytoplasm of amoeba is differentiated into an clear outer ectoplasm and a granular inner endoplasm. Later it is further distinguished into an outer stiffer or gelly like region, the plasma gel and a inner fluid region, the plasma sol.

    According to this theory the amoeboid movement involves four processes.

           (a) Attachment of amoeba to the substratum

           (b) Gelation of plasma sol at the anterior advancing pseudopodia.

           (c) Solation of plasma gel at the posterior end and receding pseudopodia.

           (d) Contraction of plasma gel at the posterior end to drive the plasma sol forward.