What is the difference between direct and indirect development?

Hint: Reproduction is a peculiar feature of all living organisms which is essential for survival and continuation of race. The sexual reproduction is characterized by the formation and fusion of gametes to form zygotes. These zygotes develop into adults. The development from zygote to adult can be direct or indirect.

Complete answer:
> Direct development:
- This is the type of development in which the embryo develops directly into a mature individual without involving a larval stage.
- There is no metamorphosis in this case.
- The young ones in direct development resemble adults.
- It occurs in fishes, reptiles, birds and mammals.

> Indirect development:
- The sexually immature larval stage is present in this type of development.
- Metamorphosis occurs in this case.
- The young ones in indirect development do not resemble adults.
- It is observed in amphibians and invertebrates.

Additional information:
Egg, larva, pupa and adult are the four stages of metamorphosis in butterflies and moths. Eggs are laid on the plants that become the food for hatching the caterpillars. The next stage is the larval stage that changes into the pupa stage which is the transition stage. When the larvae is fully grown-up and stops eating, it becomes pupa which then eventually develops into the final adult stage.

Note: The development of butterfly and moth is an example of indirect development. They develop through a process of metamorphosis. Metamorphosis is of two types- complete and incomplete metamorphosis. In complete metamorphosis the young one looks very different from adults while in complete metamorphosis, the young ones resemble adults but have no wings.