Sexual dimorphism

Sexual dimorphism is an idea in biology. It means that the male and the female of a species look different enough to see. The word comes from the Greek: "di" (two) and "morphe" (form).
It is the most common type of polymorphism. It may be caused by sexual selection, that is, competition between members of the same species for partners to reproduce. Sexual dimorphism is inherited, which means the differences between males and females help the animal stay alive in some way.
The things that make the two sexes of a species different are called secondary sex characteristics. They are not directly part of the reproductive system. They are the product of sexual selection for traits which give an animal an advantage. By "advantage" is meant: more likely to stay alive and reproduce. In humans, beards are a secondary sex characteristic. Human beings do not use beards to make babies. A man can even shave off his beard and he will still be able to have children. But men grow beards and women do not, and they are easy to see.
The difference between sexes can include:
The main functions of sexual dimorphism are to improve the individual's chance of mating in various ways:
Some animals show these differences only during mating season. Deer shed their antlers and peacocks shed their tails out of season. This minimises the key disadvantage of sexual dimorphism, which is, it makes the male much easier to be seen by predators.