Types of Movements for Locomotion

Movement is the temporary or permanent displacement of a body or its parts from its original position. Living beings and parts thereof move in response to stimulus from outside or from within the body. Locomotion, on the other hand, is the displacement of the entire body from one place to another. It is a characteristic feature of all animals, Protoctista and zoospores and zoogametes of lower plants.

Types of Movements for Locomotion

Ciliary Movements

Cilia are minute hair like processes which are motile and extend from cell surfaces. In smaller organisms like the ciliate protozoa, cilia help in locomotion from one place to another. In animals, the cilia help to propel fluids and materials. 

Cilia beat in a pattern which is different from that of the flagellum although their internal structure is the same. Ciliary beat begins with fast stroke ahead in one direction called effective stroke and then it bends back and returns to its original position. This second stroke is called recovery stroke. During ciliary beat, water is propelled parallel to ciliated surface.

Flagellar Movement

A flagellum is a long, whip like structure. While cilia cover the entire surface, flagellum is mostly present singly or in a small number at one end of a cell. Flagella occur in flagellate protozoan like Euglena or an alga like Chlamydomonas and in animal sperms. A flagellum beats symmetrically in a snake like manner and propels the water parallel to long axis of flagellum.