{"id":11072,"date":"2022-03-25T05:00:32","date_gmt":"2022-03-25T04:00:32","guid":{"rendered":"https:\/\/www.sciencefocus.com\/?p=114076"},"modified":"2022-03-25T05:14:12","modified_gmt":"2022-03-25T04:14:12","slug":"how-the-battle-of-the-sexes-left-the-duck-with-an-awkwardly-long-corkscrew-shaped-penis","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/rss_feed\/how-the-battle-of-the-sexes-left-the-duck-with-an-awkwardly-long-corkscrew-shaped-penis\/","title":{"rendered":"How the battle of the sexes left the duck with an awkwardly long, corkscrew-shaped penis"},"content":{"rendered":"

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By Sara Rigby\n \t\t<\/p>

Published: Friday, 25 March 2022 at 12:00 am<\/p>

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Duck penises are very strange. You may have read about them online, or even seen pictures, and if so, you\u2019ll know that a drake\u2019s genitalia isn\u2019t the phallic shape you might expect, but in fact is corkscrew-shaped.<\/p>\n

But why do ducks have such strange genitals? How do they have sex? And why did they evolve? We asked all of these questions to Dr Patricia Brennan, an evolutionary biologist at Mount Holyoke College, USA, and expert on duck penises. Read on to find out why Donald Duck should probably have chosen trousers instead of a sailor shirt.<\/p>\n

What do duck penises look like?<\/h2>\n
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White-headed duck \u00a9 Alamy<\/span><\/figcaption><\/div>\n

\u201cThey look a bit like a tentacle,\u201d says Brennan, with a \u201cpale colour and corkscrew shape.\u201d<\/p>\n

In some species of duck, the penis grows in the breeding season and degenerates afterwards. The size that the penis grows to depends on the environment: research led by Brennan in 2017 found that drakes that were surrounded by other males grew much longer penises<\/a> than those that lived in a pair with a female. Some even grew as long as 18cm. This species, the ruddy duck, has a total body length of only 39cm<\/a>.<\/p>\n

The lake duck, a species from South America, holds the record for the world\u2019s largest avian penis, and the longest penis in relation to body length of any vertebrate. The record holder is a specimen from Argentina, at 42.5cm long<\/a> when fully unwound, compared to an average body length of 36-46cm. For comparison, the average human erect penis is between 13 and 18cm<\/a> (5 to 7in).<\/p>\n

Guinness World Records describes the lake duck\u2019s penis as having spines around the base, and a \u201csoft and brush-like\u201d tip.<\/p>\n

Duck vaginas are also corkscrew-shaped, but turning in the opposite direction to the duck penis. \u201cThey are like a labyrinth,\u201d Brennan says. \u201cThe entrance has several blind pouches followed by a series of narrow spirals.\u201d<\/p>\n

How do ducks have sex?<\/h2>\n

\u201cQuickly!\u201d says Brennan. \u201cThe male penis everts [becomes erect] and ejaculates in a third of a second, so a brief cloacal contact is required for insemination.\u201d\u00a0(If you really want to see, here\u2019s a video<\/a>.) The drake deposits his sperm into the vagina, close to the ovary.<\/p>\n

Why did ducks\u2019 genitalia evolve like this?<\/h2>\n
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\u00a9 Shutterstock<\/span><\/figcaption><\/div>\n

Ducks\u2019 bizarre genitalia is a result of a sexual arms race. Forced mating is common among ducks, so while males\u2019 long, flexible penises increase their chances of successfully fertilising a female, the females\u2019 anticlockwise vaginas give them a level of control.<\/p>\n

\u201cThose complex structures prevent full eversion of the penis of unwanted males, so their sperm ends up closer to the cloacal entrance where the females can get rid of it more easily.\u201d That is, Brennan\u2019s research found that female ducks can prevent fertilisation from unwanted males<\/a>.<\/p>\n

However, if the female wants to mate with a certain male, she can relax her cloacal muscles to allow easier access.<\/p>\n

About our expert, Dr Patricia Brennan<\/h4>\n

Dr Patricia Brennan<\/a> is assistant professor of biological sciences at Mount Holyoke College, USA. She specialises in the evolution of genital morphology and the mechanisms that drive genital diversification. She has written several research papers on waterfowl genitalia.<\/p>\n

Read more:<\/strong><\/p>\n