I loved seeing ducks as a child. I saw the first duck I can remember at the age of 5 years old I do not know if I had seen any before then as I was still very little. Since the day I saw them, something drew my attention to them which is the fact that they are able to walk on land, fly, and swim as well. That is a lot of power to be wielded by one animal but I got a better look at them when I was in High school where they were trying to reproduce.
Ducks are a very common bird with numerous species with about 162 species and counting but these ducks are either dabbling ducks or diving ducks with the dabbling ducks cruising along the surface of water to move while diving ducks put their heads in water especially when they want to feed. The dabbling ducks use their lamellae to comb for food when looking for one especially through mud and water. This helps them filter mud and water from the food itself but in the case of diving ducks, they can dive down to water bed to look for food just as their names imply.
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wikimedia.org
Something is common about ducks either diving or dabbling which is water. They are known to live around water region and that is why their feet are specially built for that purpose. Their feet possesses webbed feet which allows them to swim like fins in fishes. Their legs are also designed not to lose lots of heat during cold times with their feet on ice or snow and so when the warm heat from the ground enters into the feet, it mixes with the cold blood coming from the feet thereby providing oxygen to the legs and preventing them from being affected in cold areas.
As a student in high school, I was able to have a closer look at ducks when they were about to mate or let me say have sex and it was at this point I knew that ducks had penises. I mean a very long one which I didn't know existed prior to that. I had always though they were similar to poultry hen and cocks but my sight of their mating experience was a completely different one. It has been seen that only 3% of birds have penises but how does this happen.
During development, a protein named Bone Morphogenetic Protein 4 (Bmp4) destroys cells that would possibly become penises which is why majority of birds do not have this reproductive organ but the protein is absent in ducks, so they have penises. The penis in ducks are a cock-screw shaped penis which is always hidden in the Cloaca sac which fall off after each mating season thereby allowing it to grow back in proportion to the competition around.
But just as the male penis is cock-screw shaped, so is the vagina of the duck a cock-screw shaped one but in the other direction with a lot of twist and turns as well as many dead ends. The female reproductive organ is believed to have evolved to become a labyrinth with many dead ends and twist. Let's not also forget that for them to reproduce, they have undergo forced copulation, and this is possibly a reason why they have their reproductive organ like that.
Reproduction is something that species do in other not to go into extinction and ducks also do this so as to protect their generations to come and we all mate differently for various evolutionary reasons but most important of all is that we continue to reproduce in other to keep our species from extinction.
https://poultrykeeper.com/duck-breeds/
https://www.yalescientific.org/2010/09/unraveling-the-mysteries-of-duck-mating/
https://campus.murraystate.edu/faculty/tderting/cva_atlases/canduck
https://www.livescience.com/4426-ducks-wage-genital-warfare.html
https://www.science.org/content/article/scienceshot-birds-disappearing-penis
https://www.smithsonianmag.com/science-nature/scientists-discover