Theory:

The new individuals born or hatched from the egg continue to grow until they become adults. In a few organisms, young ones may look very distinct and different from that of the adult.
Example:
The young one of the hen that hatches from the egg looks like the adult hen. In contrast, the young one of the frog looks very different from the adult frog.
The development of larvae(an immature form that hatches from an egg) to the adult form is metamorphosis.
Example:
Amphibians like frogs and insects like the butterfly, silkworm. An adult moth emerges from the cocoon in the case of a silkworm.
Metamorphosis in frog:
There are three distinct stages in frog development - egg, tadpole or larva, and the adult.
  1. The hatching of the fertilized frog egg produces larvae (immature young ones).
  2. The tadpole grows and develops to form the adult frog.
Important!
The tadpoles look very different from that of the adult frog.
88tl_qxua_210118_ss4mp_generated.jpg
Lifecycle of frog
 
The features of the tadpoles and the frog differs significantly.
  • Tadpole is adapted to live in water.
  • It has a long tail that aids in swimming.
  • Tadpoles breath using gills. It eventually grows into an adult by developing new bodily features.
The adult frog is an amphibian. Adult frog has webbed feet that aids in swimming and jumping or hopping in the land. It has lungs for breath inland, and moist skin helps to breathe in water.
Metamorphosis in silk moth:
Silk moth also an example for metamorphosis.
The silk moth develops from the the fertilized egg by passing the following stages.
  • The larva or the caterpillar stage
  • The pupa (cocoon)
  • The adult silk moth
Egg Larva or caterpillar Pupa Adult
 
ulgr_7ewo_181003.jpg
Life cycle of silk moth
 
Caterpillar and the pupa looks very different from that of the adult silk moth. Development occurs by the transformation of the bodily features from the egg to the adult silk moth.
Reference:
https://www.vecteezy.com/vector-art/1949388-diagram-showing-frog-life-cycle-on-white-background
https://www.vecteezy.com/vector-art/303025-science-silkworm-life-cycle