Sexual dimorphism is the condition where the two sexes of the same species exhibit different characteristics. Differences may include secondary sex characteristics, size, weight, color, or markings, as well as behavioral and cognitive differences. In the butterfly species Colias dimera (also known as the Dimera sulphur), seen here mating in Venezuela, the male on the right is a brighter shade of yellow than the female.Photograph credit: Paolo Costa Baldi
 | This picture of the day has been featured on Portal:Animals. |
 | This picture of the day has been featured on Portal:Arthropods. |