Hermaphrodite

A hermaphrodite () is a sexually reproducing organism that produces both male and female gametes. Animal species in which individuals are either male or female are gonochoric, which is the opposite of hermaphroditic. Plant species in which individuals are either male or female are dioecious. The individuals of many taxonomic groups of animals, primarily invertebrates, are hermaphrodites, capable of producing viable gametes of both sexes. In the great majority of tunicates, mollusks, and earthworms, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which either partner can act as the female or male. Hermaphroditism is also found in some fish species, but is rare in other vertebrate groups. Among plants the vast majority of angiosperms (flowering plants) are hermaphrodites. Most hermaphroditic species exhibit some degree of self-fertilization. The distribution of self-fertilization rates among animals is similar to that of plants, suggesting that similar pressures are operating to direct the evolution of selfing in animals and plants. A rough estimate of the number of hermaphroditic animal species is 65,000, about 5% of all animal species, or 33% excluding insects. Insects are almost exclusively gonochoric. There are no known hermaphroditic species among mammals or birds. About 94% of flowering plant species are either homoecious (all flowers produce both male and female gametes) or monoecious, where both male and female flowers occur on the same plant. There are also mixed breeding systems, in both plants and animals, where hermaphrodite individuals coexist with males (called androdioecy) or with females (called gynodioecy), or all three exist in the same species (called trioecy). Sometimes, both male and hermaphrodite flowers occur on the same plant (andromonoecy) or both female and hermaphrodite flowers occur on the same plant (gynomonoecy). Hermaphrodism is not to be confused with ovotesticular syndrome in mammals, which is a separate and...