(a) Sexual dimorphism is the occurrence of two sexually distinct forms such that the male differs morphologically from the female of the same species. Example includes, birds, insects, Aschelminthes etc.
(b) Difference between direct and indirect development:
| Direct development |
Indirect development |
| In this, the young ones resemble the adults in all respects except colour, size. There is no intermediate stage in direct development . |
In this, the young ones do not resemble the adults. The young ones usually pass through one or more intermediate stages before obtaining the shape of the adults. |
| E.g. Hydra, Earthworm and silver fish. |
E.g. Silk moth, housefly Frog, Butterfly |
