14.4 Locomotion In Plants
Generally plants are incapable of locomotion. But some photosynthetic protists move from one place to another with the help of flagella e.g. Euglena and volvox.
14.4.1 Locomotion In Euglena
Locomotion in euglena takes place by the lashing movements of a single long, whip-like flagellum, against the surrounding water, this whipping action of the flagellum causes it to rotate and at the same time to move forward. Some times it may show a slow wriggling movement due to alternate contraction and relaxation of the long thread like structures present in the cytoplasm. This type of movement displayed by euglena is known as Euglenoid movement, euglena does not move in a straight line but it moves in a zig zag path along with rotation on its own axis.
Fig .14.14 locomotion in Euglena
14.4.2 Locomotion in Volvox
Volvox freely floats or rolls over the surface of water looking like a minute ball of pin head size. The cells are not differentiated into tissues and organs as in plants and animals, but they form motile colonies with precisely spaced cells and containing a number of daughter colonies. The locomotion is brought about by the simultaneous action of cilia of all the cells of the colony. The eye spot- the photo-receptive organ, of each cell controls the movements of flagella.
Fig. 14.15 Locomotion in Valvox
14.5 support and movement in animals
Animals have to move from one place to other in search of food and shelter.
14.5.1 Locomotion In Amoeba
Amoeba has no special locomotory organs like flagella or cilia. It moves by the flowing movement of its protoplasm over its surface (fig. 14.21). At the surface of amoeba the fluid cytoplasm begins to flow out in to a projection called a pseudopodium. The flow of whole of the protoplasm, ultimately brings amoeba into a new position. Change of direction takes place when a new pseudopodium begins to from at another point of its surface. Direction of movements is probably determined by local differences in water. Slight acidity or alkalinity may cause the protoplasm to start flowing or prevent moving of amoeba. The chemicals diffusing from required material may cause the protoplasm to flow in that direction.
Fig. 14.16 Locomotion in Amoeba
14.5.2 Locomotion in Paramecium
Paramecium moves about at great speed. It moves with the help of its cilia which continuously beat against the water in a diagonal pattern. These cilia move forward and backward like the oars of a boat. The body of the paramecium twists itself slightly and move forwards as a result of the collective action of all the cilia. In other words body rotates on its axis while it moves forward. The animal is able to make turns and can also move backward by changing the direction of movement of its cilia.
Fig. 14.17 locomotion in paramecium