Simultaneous hermaphroditism is one of the two types of

hermaphroditism In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes. Many taxonomic groups of animals (mostly invertebrates) do not have s ...

, the other type being sequential hermaphroditism. In this form of hermaphroditism an individual has

sex organs A sex organ (or reproductive organ) is any part of an animal or plant that is involved in sexual reproduction. The reproductive organs together constitute the reproductive system. In animals, the testis in the male, and the ovary in the female, ...

of both sexes and can produce both

gamete A gamete (; , ultimately ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. In species that produce ...

types even in the same breeding season. The distinction between simultaneous hermaphroditism and sequential hermaphroditism isn’t always clear. But unlike sequential hermaphrodites, simultaneous hermaphrodites are both male and female at

sexual maturity Sexual maturity is the capability of an organism to reproduce. In humans it might be considered synonymous with adulthood, but here puberty is the name for the process of biological sexual maturation, while adulthood is based on cultural definit ...

. Also sex determination does not apply to simultaneous hermaphrodites (except in species with mix mating systems). In simultaneous hermaphrodites,

self-fertilization Autogamy, or self-fertilization, refers to the fusion of two gametes that come from one individual. Autogamy is predominantly observed in the form of self-pollination, a reproductive mechanism employed by many flowering plants. However, species ...

is possible in some species, where in others it is absent.

Plants

Most plants are simultaneous hermaphrodites with it occurring in 80% of

angiosperms Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants ...

Animals

Simultaneous hermaphroditism is one of the most common sexual systems in animals. The majority of

Cocculinoidea The Cocculinoidea is a superfamily of deepwater limpets (marine gastropods), the only superfamily in the order Cocculinida , one of the main orders of gastropods according to the taxonomy as set up by ( Bouchet & Rocroi, 2005). The clade Coccilin ...

are simultaneous hermaphrodites and it occurs in over 67% of

coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and se ...

species. The primary model explaining the evolution of simultaneous hermaphroditism from gonochorism (separate sexes) in animals is the low density model. This model explains simultaneous hermaphroditism as a reproductive adaptation to limited mating opportunities. This is advantageous to simultaneous hermaphrodites that can self-fertilize, because they are able to reproduce even if they fail to find a sexual partner. The low density model is helpful for understanding the development of simultaneous hermaphroditism in many animal species. For example, in

crustaceans Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean g ...

simultaneous hermaphroditism can be found in groups that are sessile or live in environments with limited mating opportunities.

References

{{reflist Sexual system Reproductive system Sexual reproduction