Question

Differentiate between direct and indirect development.

Answer 1

Hint: The process of development in animals starts with a single cell called zygote (a fertilized egg). The development may be direct or indirect depending on the category of animals. The progress of development from fertilization to a sexually mature adult is different in direct and indirect development.

Complete answer:
Zygote is a fertilized egg which begins to divide. The division causes differentiation of cells that leads to the formation of an embryo. The egg yolk provides nourishment to the embryo and the amount yolk determines the animals will proceed to direct or indirect deployment. The difference between direct and indirect development is given below:
Direct Development:
It is a type of development, an animal born is a small or mini version of its adult form. In this type of development there is no intermediate form such as larva of the animal. Animals which undergo direct development, their egg may have a large amount of yolk to feed the young or the young may be fed directly by the mother's body. In direct development, there is no metamorphosis. The animals that experience direct development are fishes, reptiles, birds and mammals.
Indirect Development:
It is a type of development an animal born is different from the adult form. In this type of development, the embryo hatches from the egg in a larval form. The larva undergoes a process of metamorphosis to become its adult stage. Animals that experience indirect development have very little yolk and due to the small amount of yolk, the larva develops and hatches rapidly. Amphibians, some echinoderms and some arthropods such as insects undergo indirect development.

Note: A direct development is a type of development in which a young is directly born as a small version of an adult and it develops into a mature individual without undergoing metamorphosis. Whereas, in indirect development, larva is hatched from the egg. Larva then metamorphosed to an adult.