Metamorphosis

An organism developing eventually after its birth is referred as metamorphosis. The word ‘metamorphosis’, meaning 'changes' is derived from Greek. It describes sudden change in physiological structure of an organism as it undergoes cell division and differentiation. It helps in easy prediction of physical changes by determining puberty onset stage. Johann Wolfgang von Goethe published an essay titled  ‘Metamorphosis of Plants’ in the year 1790. He described the development of flowers from seeds. He was the first to publish the term ‘homology’ fifty years ago before Richard Owen gave the definition for homology in the year 1843. Organism which undergo metamorphosis in its life cycle are amphibians, crustaceans, tunicates, echinoderms, mollusks, insects, cnidarians and insects.

Types of metamorphosis

Starting stage of metamorphosis is referred as lymph, next stage as pupa and the last stage as adult development. Pre-mature stage of metamorphosis cycle is referred as larva. Depending on the nature of metamorphosis, they are referred by different names.
Two types of metamorphosis  found in insects are

• Hemimetabolism
• Holometabolism

Hemimetabolism:

When larva is subjected to duplicate  at various stages of life cycle and moulting of cuticula, in case of arthropods as ecdysis, it is referred as instar stage. Instar juveniles are somewhat smaller with varied number of segments and body proportions. This process is also referred as simple or incomplete or gradual metamorphosis.

Holometabolism:

Next to larval stage, pupa or chrysalis and later stage as adults. This process is referred as complete or complex metamorphosis.

Typical metamorphosis stage

In general, eggs are laid in water as larvae and insects like frogs, newts and toads start hatching those laid eggs. A larva gets accustomed with aquatic marine life style. Insects capture these larvae with the help of external gills. Metamorphosis is regulated by thyroxin and prolactin concentration.