Penis of birds

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Penis of a mallard duck

The penis of birds is an analogy to the penis of mammals and, like these, the male reproductive organ . The bird penis differs significantly from the penis of mammals in the structure and mechanism of erection .

anatomy

There are two basic forms of birds:

  • Penis protrudens (evertable penis)
  • Penis non-protrudens (non-protruding penis)

When the penis protrudes (e.g. ducks , ratites , cockatoos ) there is a real copulation organ in the cloaca , which is turned outward during erection. The largest penis was measured in a drake of the Argentine black-headed rudder , whose penis was 42.5 cm long when rolled out.

The majority of birds have a non-protruding penis , which is only developed in the form of small erectable humps and folds in the cloaca. During erection they form a channel for the seminal fluid. The cloaca is turned out slightly and pressed against that of the female.

Irrespective of the type of penis, erection in birds does not take place via blood filling, but via lymph . It is produced by a vascularized formation in the cloaca wall ( Lymphobulbus phalli ).

Case study duck birds

A well-documented example of sexual selection was published in May 2007 by a US / UK research group. In this study, the genitals of various species from the duck bird family were compared. In contrast to most other birds, whose males have no external sex organs, many male ducks have developed a sex organ analogous to the penis of mammals ; in the case of the Argentine rowing duck , for example, it can be 20 to 40 cm long.

The working group examined the structure of these external genital organs of the male and the internal genital organs of the female ducks in 16 species and found that the anatomy of the female genital organs is designed in such a way that it makes it difficult for the penis to penetrate the penis without cooperation from the female duck. For example, male mallards have a relatively long, spirally wound penis. The vagina of the female mallard is also spirally wound, but in exactly the opposite direction to the penis of the male.

The individuals of one of the smallest ducks, the masked oar duck ( Oxyura dominica ), have both the longest vagina and one of the longest penises. In addition to their vaginal duct, females of other species have developed up to eight further, blind-ending “dead ends” in their genital tract: bag-like structures in which secreted sperm can not fertilize egg cells . According to the researchers, such special adaptations were only found in species in which forced copulation (in the original: "forced sex" ) by foreign males can be observed. In all other species, the males of which also have a penis, the females had simpler genitals.

The researchers concluded from their observations that the anatomical features of the sexual organs are the result of an intersexual selection and have developed parallel to the manifestation of male courtship behavior .

Diseases

Infections (including cryptosporidia and mycoplasma ) and hypersexuality can lead to a prolapse of the penis. In the event of an infectious incident, reduction can be attempted with decongestant and antibiotic ointments. If the penis is already necrotic or there is pronounced hypersexuality, amputation is recommended.

literature

  • Günther Michel: sex system. In: Salomon (ed.): Textbook of poultry anatomy. G. Fischer, Jena / Stuttgart 1993, ISBN 3-334-60403-9 , pp. 197-226.
  • Ana M. Herrera et al .: Developmental Basis of Phallus Reduction during Bird Evolution. In: Current Biology. Volume 23, No. 12, 2013, pp. 1065-1074. doi: 10.1016 / j.cub.2013.04.062
  • Walter Liebe: The male copulation organ of the domestic duck (= Jenaische Zeitschrift für Naturwissenschaften , Volume 51), G. Fischer, Jena 1914, DNB 570537118 (Dissertation University of Jena 1914, 70 pages full text online BHL Biodiversity Heritage Library Archive, p. 626ff).

Web links

Individual evidence

  1. ↑ Kevin G. McCracken, Robert E. Wilson, Pamela J. McCracken, Kevin P. Johnson: Sexual selection: Are ducks impressed by drakes' display? In: Nature . tape 413 , 2001, p. 128 , doi : 10.1038 / 35093160 ( Online ( Memento from February 10, 2012 in the Internet Archive ) PDF - en).
  2. ↑ Patricia LR Brennan, Richard O. Prum, Kevin G. McCracken, Michael D. Sorenson, Robert E. Wilson, Tim R. Birkhead: Coevolution of Male and Female Genital Morphology in Waterfowl. In: PLoS ONE. 2 (5), p. E418. doi: 10.1371 / journal.pone.0000418 , published online May 2, 2007.
  3. ↑ Michael Lierz, Anja Ewringmann: Phallus amputation after prolapse in a mallard duck. In: Small Animal Practice. 43 (1998), pp. 131-134.