Movement of Animals

1.0Earthworm 

The body of an earthworm is made up of many rings joined end to end. An earthworm does not have bones. It has muscles which help to extend and shorten the body. During movement, the earthworm first extends the front part of the body, keeping the rear portion fixed to the ground. Then it fixes the front end and releases the rear end. It then shortens the body and pulls the rear end forward. This makes it move forward by a small distance. Repeating such muscular expansion and contractions, the earthworm can move through soil. Its body secretes a slimy substance to help the movement. Under its body, it has a large number of tiny bristles (hair like structures) projecting out.

The bristles are connected with muscles. The bristles help to get a good grip on the ground. The earthworm, actually, eats its way through the soil. Its body then throws away the undigested part of the material that it eats. This activity of an earthworm makes the soil more useful for plants.

2.0Snail

The snail moves with the help of a large, disc shaped muscular foot. It deposits a little fluid at its front end and walks smoothly over this fluid. The shell is dragged along with the foot, as the shell cannot move by itself.

There are two sets of muscles in the foot of the snail which contracts and expands alternately, producing a kind of wave effect. A series of waves in the muscles of foot make the snail move forward.

3.0Cockroach

Cockroaches are insects which come out at night to feed. They can walk, climb as well as fly in the air. Two pairs of wings are present. Three pairs of legs are also present which help in walking. Bones are not present. The body is covered with a hard outer skeleton. This outer skeleton is made of different units joined together and this permits movement.

Muscles present near the legs help in walking while the breast muscles attached to the wings help in flying.

4.0Fish

Various adaptations are found in fish which help in movement.

(i) The fish has flexible backbone –

Due to its flexible backbone, the fish can bend its body easily from side to side to move through water.

(ii) The fish has fins –

The thin and flat projections on the body of fish are called fins that help in steering, balancing and stopping in water. The tail fin also helps in moving the fish forward in water.

(iii) The fish has powerful body muscles –

The powerful body muscles of fish on both sides help in moving its tail on both sides. During swimming, muscles make the front part of the body curve to one side and the tail part swings towards the opposite side. The fish forms a curve. Then, quickly, the body and tail curve to the other side. This makes a jerk and pushes the body forward. A series of such jerks make the fish swim ahead. This is helped by the fins of the tail.  Fish also have other fins on their body which mainly help to keep the balance of the body and to keep direction, while swimming.

5.0Snakes

Snakes have a long backbone and a large number of thin muscles. The muscles are connected to each other. Backbone, ribs and skin are also connected to the muscles. Movement takes place by crawling.

A snake contracts and relaxes the muscles on the two sides of its body alternately to form many loops in which different parts of the snake’s body are moving to the left side and right side at the same time. Each sideways moving loop of the snake pushes back against the ground and gives the snake a forward push. The resultant push of all the loops of the snake's body make it move forward very fast. The wave- like motion of the snake is “slither”.

6.0Birds

Birds are adapted to fly in the air and walk on the ground. Birds like ducks and swans swim in water. Birds walk on the ground by using their hind limbs. Those birds which swim in water do so by pushing against water with their hind limbs which have webbed feet that helps in swimming.

Birds have following adaptations which enable them to fly –

(i) Their forelimbs are modified to form wings for flying.

(ii) Their flight feathers provide a large flat surface which is light but strong.

(iii) Their bones are hollow and light.

(iv) Their bodies are streamlined and extremely light.

(v) They have powerful flight muscles.

(vi) Their breastbone is extended for the attachment of large flight muscles.

7.0Also Read