Grade 8 Science : Life Cycles of living organisms - Part 2

The human life cycle too is embedded with various phases and except the size, the infants tend to resemble their adults and they undergo the stages of birth, adolescence, reproduction and death. These stages will portray the morphological features that are similar to that of their adults.  However, in the case of animals like butterflies, frogs and cockroaches, the respective stages in their life cycle showcase the morphological features that are different from each other. Metamorphosis is the term given to this process as consists of different morphological changes in each stage of life cycle and this applies only to some organisms. For an instance, our life cycle (humans) does not possess metamorphosis as the developmental stages evolve.  Typically, metamorphosis is portrayed by the life cycles of amphibians and insects. There exist two major forms of metamorphosis, namely complete metamorphosis and incomplete metamorphosis. The metamorphosis that consists of distinct features can be cited as complete metamorphosis.

 

Here, the mechanisms like digestion, locomotion and etc. differ at each stage along with the physiological changes. The life cycles of mosquitos, frogs, butterflies and bees showcase complete metamorphosis. On the other hand, the life cycles of some insects like cockroach, dragon fly, termites, lice and grasshoppers do not display any significant morphological or physiological changes in the stages go through incomplete metamorphosis. They hatch from eggs and appear smaller than the adults. However, they normally resemble the adults in appearance as they undergo all the stages. If we take the life cycle of a butterfly that consists of complete metamorphosis, it possesses the four stages namely, eggs, larva, pupa and the adult stage. On the contrary, in the case of the life cycle of a cockroach that has incomplete metamorphosis, it consists of the stages of eggs, nymph and the adult. Conclusively, metamorphosis literally refers to “change” and it reflects the sequence of changes through which the organisms pass from the initial stage to the adult stage.

 

 

 

 

 

 

 

 

 

 

by Mekhala Egodawele

Photo source : Internet