Movement in Earthworm


 
 
Concept Explanation
 

Movement In Earthworm

By movement we usually mean displacement from one place to another. In case of animals movement means simply moving body or limb - that is, change their position. Locomotion means movement of animals from one place to other.

Earthworm 

Earthworms have liquid skeletons. They have liquid trapped in spaces inside the body. The muscles squeeze against the liquid. This keeps the body firm. The earthworm first extends the front part of its body, keeping the rear part fixed to the ground. Next, it fixes the front part and shortens it, thus pulling the rear end forward.It has a long cylindrical body made up of many rings or segments joined end to end. It carries out such expansion and contraction of muscles repeatedly to move forward. There are two types of muscles in an earthworm's body - circular and longitudinal muscles. When circular muscles contract, the segments become long and thin. When longitudinal muscles contract, the segments become short and thick.

To move, first the earthworm contracts the circular muscles of the front segments. As a result, the front part of the body becomes long and moves a little ahead by withdrawing the bristles from the ground. Then, the longitudinal muscles of the front part of the earthworm contract and segments become short and thick. The bristles of the front part now grip the ground and the segments in the rear part of the earthworm become thin and long due to contraction of circular muscles. 

                                                                  

Sample Questions
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Question : 1

Which of these help caterpillar and earthworm to move?

Right Option : A
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Question : 2

The  _________________ in earthworms help to get a good grip on the ground

Right Option : D
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Question : 3

Which of the following are correct ?

(a) To move, first the earthworm contracts the circular muscles of the front segments.

(b) The front part of the body becomes short and moves a little ahead by withdrawing the bristles from the ground.

(c) The longitudinal muscles of the front part of the earthworm contract and segments become short and thick.

Right Option : B
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Explanation
 
 


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