Intersex (biology)

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This article is about intersex from a more biological perspective and intersex across species. For intersex in humans, see Intersex.

Intersex is a general term for an organism that has sex characteristics that intermediate between male and female.[1] The term intersex typically applies to abnormal members of gonochoric species that are usually sterile.[2] It is not to be confused with the term hermaphrodite.[3]

Intersexuality has been reported in mammals, fishes, nematodes, and crustaceans.

Mammals[]

Intersex can also occur in non-human mammals such as pigs, with it being estimated that 0.1% to 1.4% of pigs are intersex.[4]

Nematodes[]

Intersex is known to occur in all main groups of nematodes. Most of them are functionally female. Male intersexes with female characteristics have been reported but are less common.[5]

Fishes[]

Gonadal intersex also occurs in fishes, where the individual has both ovarian and testicular tissue. Although it is a rare anomaly among gonochoric fishes, it is a transitional state in fishes that are protandric or protogynous.[6] Intersexuality has been reported in 23 fish families.[7]

Crustaceans[]

The oldest evidence for intersexuality in crustaceans comes from fossils dating back 70 million years ago.[8] Intersex has been reported in gonochoric crustaceans as early as 1729. A large amount of literature exists on intersexuality for isopoda and amphipoda, with there being reports of both intersex males and intersex females.[9]

See also[]

References[]

  1. ^ "intersex | Definition & Facts". Encyclopedia Britannica. Retrieved 2021-07-10. Intersex, in biology, an organism having physical characteristics intermediate between a true male and a true female of its species.{{cite web}}: CS1 maint: url-status (link)
  2. ^ "Malformation - Sexual anomalies". Encyclopedia Britannica. Encyclopædia Britannica, Inc. Retrieved 19 July 2021.
  3. ^ Farrell A (2011-06-01). Encyclopedia of Fish Physiology: From Genome to Environment. Academic Press. ISBN 978-0-08-092323-9. Thus, strictly speaking, all hermaphrodites are intersex at one time point, but not all intersexes are hermaphrodites. This definition is usually applied to gonochoristic species to describe those individuals that are not normal for the species.
  4. ^ Hunter, R. H. F.; Hunter, Ronald Henry Fraser (1995-03-09). Sex Determination, Differentiation and Intersexuality in Placental Mammals. Cambridge University Press. p. 157. ISBN 978-0-521-46218-1.
  5. ^ El-Bawab, Fatma (2020-01-18). Invertebrate Embryology and Reproduction. Academic Press. p. 431. ISBN 978-0-12-814115-1.
  6. ^ Norris, David O.; Lopez, Kristin H. (2010-11-25). Hormones and Reproduction of Vertebrates. Academic Press. pp. 249–251. ISBN 978-0-08-095809-5.
  7. ^ Pandian, T. J. (2010-09-15). Sexuality in Fishes. CRC Press. p. 38. ISBN 978-1-4398-4669-8.
  8. ^ Ford, Alex T. (February 2012). "Intersexuality in Crustacea: an environmental issue?". Aquatic Toxicology (Amsterdam, Netherlands). 108: 125–129. doi:10.1016/j.aquatox.2011.08.016. ISSN 1879-1514. PMID 22265612.
  9. ^ Cothran, Rickey; Thiel, Martin (2020-04-24). The Natural History of the Crustacea: Reproductive Biology: Volume VI. Oxford University Press. pp. 395–396. ISBN 978-0-19-068855-4.
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