AskDefine | Define hermaphrodites

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English

Noun

hermaphrodites
  1. Plural of hermaphrodite

French

Adjective

p
  1. Form of plural, hermaphrodite

Extensive Definition

A hermaphrodite is an organism having both male and female reproductive organs. In many species, hermaphroditism is a common part of the life-cycle, enabling a form of sexual reproduction in which the two sexes are not separated into distinct male and female types of individual. Hermaphroditism most commonly occurs in invertebrates, although it is also found in some fish, and to a lesser degree in other vertebrates.
Historically, the term hermaphrodite has also been used to describe ambiguous genitalia and gonadal mosaicism in individuals of gonochoristic species, especially human beings. The term comes from the name of the minor Greek god Hermaphroditus, son of Hermes and Aphrodite (see below).
Recently, intersex has been used and preferred by many such individuals, encouraging medical professionals to use the term.

Zoology

Sequential hermaphrodites

Sequential hermaphrodites (dichogamy) occurs in species in which the individual is born as one sex but can later change into the alternate sex. This is in contrast with simultaneous hermaphrodites, in which an individual may possess fully functional male and female gonads. Sequential hermaphroditism is common in teleost fish, especially marine reef species. While some sequential hermaphrodites can change sex multiple times, most can only change sex once.
Sequential hermaphrodites fall into two broad categories:
  • Protandry: Where the organism is born as a male, and then changes sex to a female.
    • Example: The Clownfish (Genus Amphiprion) are colorful reef fish found living in symbiosis with anemones. Generally one anemone contains a 'harem', consisting of a large female, a smaller reproductive male, and even smaller non-reproductive males. If the female is removed, the reproductive male will change sex and the largest of the non-reproductive males will mature and become reproductive. It has been shown that fishing pressure can change when the switch from male to female occurs, since fishermen naturally prefer to catch the larger fish. The populations are generally changing sex at a smaller size, due to artificial selection.
  • Protogyny: Where the organism starts as a female, and then changes sex to a male.
    • Example: Wrasses (Family Labridae) are a group of reef fish in which protogyny is common. Wrasses also have an uncommon life history strategy, which is termed diandry (literally, two males). In these species, two male morphs exists: an initial phase male or a terminal phase male. Initial phase males do not look like males and spawn in groups with other females. They are not territorial. They are perhaps, female mimics (which is why they are found swimming in group with other females). Terminal phase males are territorial, and have a distinctively bright coloration. Individuals are born as males or females but if they are born males, they are not born as Terminal Phase males. Females and initial phase males can become terminal phase males. Usually the most dominant female or initial phase male replaces any terminal phase male, when those males die or abandon the group.
Sequential hermaphrodites possess an ambisexual gonad. The gonad has both a male and a female portion. When an individual changes sex, gonad remodeling occurs. Interestingly, changes in behavior often occur before these gonad changes.

Simultaneous hermaphrodites

A simultaneous hermaphrodite (or synchronous hermaphrodite) is an adult organism that has both male and female sexual organs at the same time. Usually, self-fertilization does not occur.
  • Snails are perhaps the most classic of simultaneous hermaphrodite, and the most widespread of terrestrial animals possessing this sexual polymorphism. Using calcium carbonate 'arrows' as sperm carriers which are exchanged between snails by shooting them, sexual material is exchanged between both animals. In this way, snails have been poetically compared with Cupid for their sharing of shooting 'Arrows of Love'. After exchange of spermatazoa, both animals will lay fertilized eggs after a period of gestation, which then proceed to hatch after a development period. Snails typically reproduce in early spring and late autumn.
  • Hamlets, unlike other fish, seem quite at ease mating in front of divers, allowing observations in the wild to occur readily. They do not practice self-fertilization, but when they find a mate, the pair takes turns between which one acts as the male and which acts as the female through multiple matings, usually over the course of several nights.
  • Earthworms are another example of a simultaneous hermaphrodite. Although they possess ovaries and testes, they have a protective mechanism against self fertilization and can only function as a single sex at one time. Sexual reproduction occurs when two worms meet and exchange gametes, copulating on damp nights during warm seasons. Fertilized eggs are protected by a cocoon, which is buried on or near the surface of the ground.
  • Banana Slugs are one more simultaneous hermaphrodite example. Mating with a partner is most desirable, as the genetic material of the offspring is varied, but if mating with a partner is not possible, self-fertilization is practised. The male sexual organ of an adult banana slug is quite large in proportion to its size, as well as compared to the female organ. It is possible for banana slugs, while mating, to become stuck together. If a substantial amount of wiggling fails to separate them, the male's organ will be bitten off (with the slug's radula). If a banana slug has lost its male sexual organ, it can still self-fertilize, making its hermaphroditic quality an invaluable adaptation.

Other

Hyenas have a clitoris that is greatly enlarged, so much so, that they were described as hermaphrodites -- not only by the ancient Greeks, but as recently as the twentieth century among circus animal handlers -- until scientific information was provided that clarified the misunderstanding.

Botany

Hermaphrodite is used in botany to describe a flower that has both staminate (male, pollen-producing) and carpellate (female, ovule-producing) parts. This condition is seen in many common garden plants. A closer analogy to hermaphrodism in animals is the presence of separate male and female flowers on the same individual—such plants are called monoecious. Monoecy is especially common in conifers, but occurs in only about 7% of angiosperm species (Molnar, 2004).

Notes

References

  1. Randall, John E.,(2005) Reef and Shore Fishes of the South Pacific, Univ. of Hawaii Press, p346 and 387. ISBN 0-8248-2698-1
  2. SeaWorld/Busch Gardens Animal Information Database, "Fish Reproduction"
  3. Kyu-Rae Kim M.D., et al. True Hermaphroditism and Mixed Gonadal Dysgenesis in Young Children: A Clinicopathologic Study of 10 Cases, Modern Pathology, 2002;15(10):1013
  4. Discovery Health Channel, (2007) "I Am My Own Twin"

Further reading

  • Anne Fausto-Sterling, "How Many Sexes Are There?" from The New York Times, Op-Ed page, March 12, 1993, reprinted in Sterling Harwood, ed., Business as Ethical and Business as Usual (Belmont, CA: Wadsworth Publishing Co., 1996), pages 168-170.
  • M.M. Grumbach, and F.A. Conte. 1998. "Disorders of sex differentiation." in Williams Textbook of Endocrinology, eds. J.D. Wilson, D.W. Foster, H.M. Kronenberg, and P.R. Larsen, (Philadelphia: W B Saunders:1303-1425).
  • Molnar, Sebastian. 2004. Plant Reproductive Systems, internet version posted February 17, 2004.
  • Kyu-Rae Kim M.D., et al. True Hermaphroditism and Mixed Gonadal Dysgenesis in Young Children: A Clinicopathologic Study of 10 Cases, Modern Pathology, 2002;15(10):1013–1019
  • Chase, Cheryl. (1998). "Affronting Reason" in Looking Queer: Body Image and Identity as Lesbian, Bisexual, Gay and Transgender Communities, edited by David Atkins, pages 205-219. (Publishing 1998 Haworth Press).
hermaphrodites in Breton: Divreizhadezh
hermaphrodites in Catalan: Hermafrodita
hermaphrodites in Czech: Hermafrodit
hermaphrodites in Danish: Hermafrodit
hermaphrodites in German: Hermaphroditismus
hermaphrodites in Estonian: Hermafrodiit
hermaphrodites in Spanish: Hermafroditismo
hermaphrodites in French: Hermaphrodisme
hermaphrodites in Croatian: Hermafroditizam
hermaphrodites in Korean: 자웅동체
hermaphrodites in Italian: Ermafroditismo
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hermaphrodites in Japanese: 雌雄同体
hermaphrodites in Norwegian: Hermafrodittisme
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hermaphrodites in Simple English: Hermaphrodite
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