Metamorphosis in Frog and Butterfly


 
 
Concept Explanation
 

Metamorphosis in Frog and Butterfly

We know that a number of animals (such as birds, frogs and insects, etc.) are hatched from eggs. For example, chicks are hatched from the eggs of hens. Similarly, the frogs and silk moths are also hatched from their eggs.

  • Now, when a chick comes out of the egg of a hen, its over-all appearance is almost the same as that of an adult hen except that it is much smaller than the hen.
  • So, when a small chick grows and develops to become an adult hen (or cock), then there is not much change in its body appearance.
  • That is, the young one of hen (chick) hatched from the egg and the adult hen look alike.
  • But this is not so in the case of animals such as frogs and silk moths, etc. For example, the young ones (larvae or tadpole) in frogs hatched from the eggs look very different from the adult frogs.
  • The process of transformation from an immature form of an animal like "larva' to its 'adult form' in two or more distinct stages, is called metamorphosis. In most simple words, the change of a larva to an adult animal is called metamorphosis.
  • Metamorphosis occurs in amphibians (like frogs) and insects (such as silk moth, butterfly, housefly and mosquito, etc.
  • Metamorphosis :  It is a biological process of transforming larva into an adult. There occur changes in the animal body through cell growth and development. Some insects, amphibians, molluscs, cnidarians, echinoderms etc. undergo metamorphosis. There are three main stages in the life cycle of a frog :

    (i) Egg       (ii) larva (tadpole)       (iii) adult

    Tadpole that emerges out oft the egg looks completely different from the adult. They can swim freely in the water. The metamorphosis of tadpole begins with the development of limbs, lungs development and finally the absorption of tail by the body.These changes are controlled by the hormone thyroxin.

    In the similar way a beautiful butterfly emerges out of cocoon. The caterpillar undergoes metamorphosis. It changes its colour and its body contracts. As a result the tissue become fluid and begin forming organs of adult butterfly .Within  few days, once the development is complete a beautiful butterfly emerges out of the pupil shell. The adult will continue the cycle and reproduce. 

         

    Metamorphosis in Silk Moth :

    Silk moth is an insect (like butterfly) which undergoes metamorphosis during its life cycle. The silk moth passes through the larva and pupa stages during its development after hatching from the egg and forms an adult silk moth. The various stages in the development of a silk moth can be represented as follows :

    Egg ; overset{Hatching}{rightarrow}; Caterpillar; overset{Metamorposis }{rightarrow};Pupa;overset{Metamorphosis}{rightarrow};Silk ;moth

    (of silk moth)            (Larva)                                   (Chrysalis)                           (Adult)

    The changes during the formation of an adult silk moth from its egg can be shown by diagrams as follows :

    NOTE : The caterpillar (larva) and pupa stages in the development look very different from the adult silk moth. So, there have been drastic changes in appearance during the transformation of caterpillar into the adult silk moth. Thus, the change from caterpillar to a silk moth is an example of metamorphosis.

    We (human beings) also observe changes in our body appearance as we grow but these changes are not drastic changes. In human beings, the body parts in adults are similar to those which are present in babies from the time of birth. So, human beings do not undergo metamorphosis.

    The common animals such as cats, dogs, hens, tiger, lion, deer, horse, cow, etc., also do not undergo metamorphosis during their life cycle.

    Sample Questions
    (More Questions for each concept available in Login)
    Question : 1

    Which of the following are correct :

    (a) Metamorphosis occurs in amphibians (like frogs) and insects (such as silk moth, butterfly, housefly and mosquito, etc.

    (b) Metamorphosis occurs in animals such as cats, dogs, hens, tiger, lion, deer, horse, cow, etc.

    (c) The silk moth passes through the larva and pupa stages during its development after hatching from the egg and forms an adult silk moth.

    Right Option : C
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    Explanation
    Question : 2

    Which of the following is not a stage in life cycle of Silk moth?

    Right Option : C
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    Explanation
    Question : 3

    Frogs and butterflies exhibit complete _____________ for their developmen.

    Right Option : A
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    Explanation
     
     
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