The hydra live attached by their pedal discs to objects in water.Depending on the colour the brown and white hydra can fixed at one spot for some time but green hydra move about tfrom one place to another by several ingenious devices.All the movements are caused by the contraction or the expansion of the contractile muscles fibres. The gastro dermal muscles fibres are less developed in most part of the body wall,the movements are largely due to the contraction of the epidermal muscles fibres.
1>EXPANSION AND CONTRACTION-It is the process by which hydra ,when hungry ,remain attached to a substratum in water and frequently expands and contracts itself at intervals.This process is called contraction burst.This behaviour of hydra is guide by pacemaker located inhypostome. The contraction of one side and elongation of other side of the body or tentacles result in the bending and swaying movements which assist in the capture of prey.
2>LOOPING-The hydra also move from one place to another in search of food.With the help of glutinant nematocysts the tentacles attach to the substratum. The pedal disc is released and brought up closer to the circlet of tentacles and attached .The whole process which is repeated again again appear like a series of looping movements of a caterpillar or leech.
3>SOMERSAULTING-It is process of progression the animal somersaults like an acrobat.It is a slight modification of the looping locomotion.It result in hydra to assume an inverted posture.Hydra perform a series of somersaults by repeating the process.
4>GLIDING-IT can slide or glide slowly over the substratum due to creeping amoeboid movements of the cells of the pedal disc.
5>WALKING-The type of movements take place on some objects such as leaf and in leisurely hours.It can be slide or glide slowly over the substratum due to the creeping amoeboid movements of the cells of the pedal disc.
6>CLIMBING-Some hydra e.g pelmatohydra oligactis can evn climb by attaching its ling tentacles to some objects releasing the foot,and then contracting the tentacles ,so the body is lifted up.
7>FLOATING-The hydra throws its body free and floats on the water surface with the waves in water.
8>SURFACING-Hydra uses a gas bubbles secreated in mucus by the cells of the pedal disc,to rise in water and float at the surface.
9>SWIMMING-The some hydra free it self from the substratum and swims in water by the undulating wave-like movements of the tentacles and the body.
1>EXPANSION AND CONTRACTION-It is the process by which hydra ,when hungry ,remain attached to a substratum in water and frequently expands and contracts itself at intervals.This process is called contraction burst.This behaviour of hydra is guide by pacemaker located inhypostome. The contraction of one side and elongation of other side of the body or tentacles result in the bending and swaying movements which assist in the capture of prey.
2>LOOPING-The hydra also move from one place to another in search of food.With the help of glutinant nematocysts the tentacles attach to the substratum. The pedal disc is released and brought up closer to the circlet of tentacles and attached .The whole process which is repeated again again appear like a series of looping movements of a caterpillar or leech.
3>SOMERSAULTING-It is process of progression the animal somersaults like an acrobat.It is a slight modification of the looping locomotion.It result in hydra to assume an inverted posture.Hydra perform a series of somersaults by repeating the process.
4>GLIDING-IT can slide or glide slowly over the substratum due to creeping amoeboid movements of the cells of the pedal disc.
5>WALKING-The type of movements take place on some objects such as leaf and in leisurely hours.It can be slide or glide slowly over the substratum due to the creeping amoeboid movements of the cells of the pedal disc.
6>CLIMBING-Some hydra e.g pelmatohydra oligactis can evn climb by attaching its ling tentacles to some objects releasing the foot,and then contracting the tentacles ,so the body is lifted up.
7>FLOATING-The hydra throws its body free and floats on the water surface with the waves in water.
8>SURFACING-Hydra uses a gas bubbles secreated in mucus by the cells of the pedal disc,to rise in water and float at the surface.
9>SWIMMING-The some hydra free it self from the substratum and swims in water by the undulating wave-like movements of the tentacles and the body.
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ReplyDeleteexplanation is short and simple and can be understood by ayone
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