Sexual dimorphism is that the condition where the 2 sexes of an equivalent species exhibit different characteristics beyond the differences in their sexual organs. The condition occurs in many animals and a few plants. Differences may include secondary sex characteristics, size, weight, colour, markings, and should also include behavioral and cognitive differences. These differences could also be subtle or exaggerated, and should be subjected to sexual selection and survival . the other of dimorphism is monomorphism. Common and simply identified sorts of dimorphism contains ornamentation and coloration, though not always apparent. A difference in coloration of sexes within a given species is named sexual dichromatism, which is usually seen in many species of birds and reptiles. In redlip blennies, only the male fish develops an organ at the anal-urogenital region that produces antimicrobial substances. During parental care, males rub their anal-urogenital regions over their nests' internal surfaces, thereby protecting their eggs from microbial infections, one among the foremost common causes for mortality in young.