Locomotion in
Euglena
Euglena is a very
active micro-organism and moves at a great speed. Movement is caused by the
lashing movement of the long flagellum against the surrounding water. The
flagellum is present at the anterior end of the organism. The whipping action
of the flagellum causes it to rotate and at the same time move forward. The
flagellum has 9+2 arrangement of the fibrils. Five fibrils will contract simultaneously
to bend flagellum, and then four fibrils will contract simultaneously to
straighten the flagellum.
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| Locomotion in Euglena |
Euglena is able to
change its direction by the active contractile myonemes which run along the
length of its body. When the myonemes contract the shape of the body is changed
as well as its direction. The movement displayed by Euglena is known as
euglenoid movement.
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| Locomotion in Paramecium |
Locomotion in
Paramecium
Paramecium moves about
at a great speed. It moves with the help of cilia and it is called ciliary
movement. Alt the cilia do not move simultaneously, a bunch of cilia move in a
progressive wave like manner at a time. The wave starts at the anterior end and
progresses in the backward. The body of the Paramecium rotates on its axis
while it moves forward. Paramecium is able to make turns and can also move
backwards by changing the direction of movement of its cilia.
Structure
of cilia: Cilia are short, fine thread like extensions of the
cell membrane. The length of the cilia ranges from many microns to many hundred
microns and the diameter varies in from 0.1 to 0.5 micrometer. A cilium
consists of series of continuous fibers which run longitudinally through the
entire cilium. There are nine peripheral fibers, each made of two sub-fibers
joined together to form a double and two central fibers. The 9 + 2 fibers are
made of microtubule. The fibrils are covered by the extension of cell membrane.
Mechanism
of movement: In 1955 Bradford suggested that
movement of cilia is due to sliding of double fibrils in two groups one after
the other.
(a)
Effective stroke: Five out of nine double fibrils
contract or slide simultaneously.
As a result cilium
bents or shortens. It is called effective stroke.
(b)
Recovery stroke: Four out of nine double fibrils contract
and cilium becomes straight. It is called recovery stroke. As a result of this
Paramecium swims against water.
Energy:
The energy for ciliary movement is provided by ATP. The enzyme ATP-ase, splits
ATP and stops ciliary action.
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| Locomotion in Amoeba |
Co-ordination:
The cilia are coordinated. Thousands of cilia beat together to move the animal
in a direction.
Locomotion in Amoeba
Movement in Amoeba takes
place by means of pseudopodia. The formation of pseudopodium is initiated by a
local weakening in plasmagel (hyaline ectoplasm). The outer motionless part of
endoplasm of pseudopodium is formed when the plasmasol (the inner moving
portion of endoplasm) begins to flow in to the weakening region as a result of
the contraction of elastic plasmagel. This contraction of plasmagel is believed
due to the osmotic forces. As the plasmasol flows out in the form of an
extension, its sides are actually changing into gel, forming a sort of
plasmagel tube along which the stream of plasmasol (endoplasmic stream) can
grow. At the so called posterior end it changes into plasmasol and plasmasol
flows forward. Thus the remaining bulk of body of Amoeba is able to change position.
This type of movement is called amoeboid movement.
Locomotion in
Jellyfish
Jelly fish has an
umbrella like body called bell. The water enters the bell then the animal
closes the umbrella and the bell contracts to force out water in a jet. As a
result animal moves in upward direction. This types of movement is known as jet
propulsion.
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| Locomotion in Jellyfish |
Locomotion in
Earthworm
The organ of locomotion
is setae or bristles. Setae are present externally on each segment. The setae
of the posterior part become extended and become attached to the soil. The
longitudinal muscles of the body wall are then relaxed and circular muscles are
contracted. As a result anterior part moves forward over the surface of soil.
Then the setae of the anterior part extend and hold the soil surface, and setae
of the posterior part are withdrawn. Now the circular muscles relax and
longitudinal muscles contract, due to which the posterior part of the body is
drawn forward. The posterior region is again fixed and the anterior region is
extended forward and the whole process is repeated. So an earthworm shows an
accordion like movement.
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| Locomotion in Earthworm |
Locomotion in
Cockroach
Cockroach has three
pairs of legs and two pairs of wings.
Walking: In walking the
legs of one side are used. The foreleg pulls the body forwards and hind leg
pushes it in the same direction. The middle leg of the opposite side acts as
prop. The remaining three legs begin to move together and the process is
repeated. For movement of legs antagonistic pair of muscles are used.
Flying:
The posterior pair of wings bring about the flight. These beat in air in such a
manner that they support the body weight and drive it through the air.
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| Locomotion in Cockroach |
Locomotion in Snail
Snails crawl or move very
slowly by the muscular foot.
Locomotion in
Starfish
Locomotion is performed
by tube feet which are alternatively attached and released from the substratum.
In the direction of movement one or two arms are raised. The sucker contracts
with the help of circular muscles, as a result of this, tube feet elongate and
project towards and adhere firmly to the substratum by vacuum action of the
sucker. The tube feet take a vertical posture with the help of muscular
activity. As a result the body is dragged forward. Then the tube feet contract
with the help of longitudinal muscles and forces some water back to their
ampullae. Then the sucker releases their hold from the substratum.
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| Locomotion in Starfish |
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