Duck sexual practice is far more interesting than it has any right to be , due to the perverted nature of the birds ’ genitals . virile and female ducks have bottle screw - shaped sex activity reed organ which corkscrew in different directions . Now we know why .
Ducks are know for their outre penises , stretching up to 20 centimeter in size of it in an anti - clockwise helix . That ’s an impressive organ for a bird often only 60 curium long . The female , on the other hand , have vaginas that spiral clockwise , opposite to their menfolk . Ducks also engage in what is courteously termed “ forced copulation ” , where the manly ducks undertake non - consensual sex activity with the female person , and explosively extend their member with a proficiency that takes less than half a second .
This forceful mating is something the female essay to avoid . as luck would have it , organic evolution is on their side . distaff ducks have evolve vagina that spiraling clockwise , and contain tart turns , which scientists trust were used to keep insemination by undesirable suitors . This possibility has finally been tested by enterprising researchers at Yale , with too much meter and glassware on their mitt . With curing of cylindric glass tubes shaped into clockwise or anti - clockwise spirals , they test how easily the phallus advanced through various vaginal conformation . The clockwise vaginas contend to halt the horn in harmonium , protect the female duck form unwanted advances .
In fact , the bulk of pull copulation do n’t result in fertilisation , and it appears the two gender are demand in an arms raceway over their genitalia , with male person evolve newfangled attacks and the female refutation . The twisted vagina can completely stop the phallus from its explosive travail , preventing undesirable genes from being passed on . This helps discontinue unsought advances , and let females retain ascendance over who will reproduce successfully with them .
It may not be avagina dentata , but it ’s a tightlipped approximation .
[ viaYale ]
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