noun, plural: sexual dimorphisms
Sexual dimorphism is the occurrence of morphological difference between the male and the female of the same species aside from the distinction in sexual organs. It can be observed in many organisms, such as certain plants, birds, insects, trematodes, etc.
A common example involves differences in coloration and ornamentation. For instance, in peafowl, the plumage of a peacock is more colorful and elaborate than that of a peahen. The peahen has subdued plumage whereas the peacock has an ornate plumage. The peacock uses its plumage for courting and attracting peahen. Another is the color distinction in the plumage of mallards. The male mallard has a bright green plumage on its head whereas the female mallard has light plumage.
Certain spiders also show sexual dimorphism. For instance, the Hawaiian garden spiders (Argiope appensa), have marked morphological differences. The male spider is a lot smaller than the female spider of this species. A typical male is only about 1.9 cm whereas the female ranges from 5.1 to 6.4 cm in length.