Types of Movement

TYPES OF MOVEMENTS

Movements can be of 2 categories.

1.Non-Muscular Movements:

These movements persist in the animals in some of their cells.

(i) Protoplasmic Streaming: Streaming of protoplasm called cyclosis, has been seen in most of the cells such as leucocytes, Amoeba and other unicellular organisms.

(ii) Pseudopodial Movements: Leucocytes and macrophages move about in the tissues with the help of pseudopodia in the same manner as of Amoeba.

(iii) Flagellar Movements: The flagella of certain cells (e.g., choanocytes of poriferans) maintain by their ceaseless vibrations a regular current of water through the canal system of sponges. The flagella of certain gastrodermal cells circulate fluid in the coelenteron of Hydra by regular beating. Sperms swim in water or in female genital tract by flagellar movements.

(iv) Ciliary Movements: The cilia of the cells lining the trachea, oviducts and vasa efferentia propel dust particles, eggs and sperms in specific direction. The cilia of flame cells push waste material in excretory canals in flatworms.

The non-muscular ciliary locomotion is retained by some animal larvae such as the planula larva of coelenterates and the trochophore of annelids, and even some adults such as planarians.

2.Muscular Movements:

This depends upon the use of muscle fibres which have ability to exert force by alternate contraction and relaxation.

Most multicellular organisms have muscle fibres for moving different body parts or locomotion.

A muscle contraction does not always result in movement. It may at times maintain status quo, as in a fresh water mussel (mollusc), muscle contract to keep shell closed for safety.