Question

Differentiate between direct and indirect development.

Answer 1

Hint: Direct development can be defined as the presence of lots of nourishing yolks in the embryo that can result in the development of a miniature adult. Indirect development can be referred to as the presence of a little yolk inside the embryo which will result in the development of the larva that can be fed by the young adults. Mammals have a very little yolk but it can nourish the embryo by the placenta.

Step by step answer:The difference between direct and indirect development is as follows:

Characters	Direct development	Indirect development
Definition	It is a type of embryonic development in which an embryo develops from a large amount of yolk without involving a larval stage.	It is a type of embryonic development in which a little amount of yolk is involved and this developmental process involves sexually-immature larvae that have different food requirements than adults.
Metamorphosis	Absent.	Present. It involves the development of sexually mature adults from sexually immature larvae.
Stages of maturity	Intermediate stages are absent.	Intermediate stages are present.
Resemblance of adults	The Young one resembles the adult.	In the young hatching larva, larvae do not resemble the adults.
Example	Hydra, fishes, reptiles, birds, and mammals like humans.	Invertebrates like cockroaches and amphibians like frogs.

Note: This is a part of reproductive classification. This classification is done on the basis of eggs that are laid by different animals. Based on the quantity of yolk present inside the egg, the eggs can be divided into three groups – Microlecithal eggs, Mesolecithal eggs, and Macrolecithal eggs. Similarly, based on the distribution of yolk of the egg in the cytoplasm, these eggs are classified in four types – Homolecithal eggs, Telolecithal eggs, Mesolecithal eggs, and Centrolecithal eggs.