Comparison between Metamorphosis in Amphibians and Insects
You may have realized that the metamorphic process in amphibians and insects show certain fundamental similarity. May be you have been able to identify them. They are described below:
(1) Metamorphosis in both involves some destructive activities (histolysis) and some constructive activities (histogenesis).
(2) Larval growths in amphibians is not divisible into instars or inter stages. Instead, it is continuous development. In insects, growth occurs periodically marked by moults. There seems to be no growth in the intermoult period.
(3) The juvenile hormone of insects however has no counterpart in amphibians and so in amphibians there is no hormone which can check or prevent precocious development.
(4) In both insects and amphibians the stimulus necessary for the secretion of hormone responsible for initiation of metamorphosis is provided by secretory organs associated with the brain, namely hypothalamus in amphibians and protocerebrum in insects.
(5) In both amphibians and insects the brain and its secretion does not act directly on the larval tissue, instead they stimulate the secretion of another endocrine gland, the thyroid in amphibians and the prothoracic gland in insects.
(6) In both cases the hormones influence differentiation of cells and morphogenetic processes during metamorphosis.