This one is bizarre. The
Argentine blue-billed duck:
Quote:
http://mercury.bio.uaf.edu/~kevin_mc...re-413-128.pdf
This small duck (which typically weighs around 640 g) was previously reported to have a 20 cm penis, which is about half the drake's total body length and is comparible to the penis of an ostrich(Struthio camelus). A new voucher specimen from Argentina's Cordoba pronvince(Fig 1) indicates, however, tha tthe penis size of this species was underestimated. We measured the length of the unwound, everted penis of an aroused O. vittata drake and found that it was 32.5 cm long when hanging under the force of gravity, but could stretch when fully unwound to 42.5 cm.
One explanation for the evolution of such a long penis is competitive advantage -- for instance, groups of drakes might display their everted penises to attract females. Success in sperm competition may also be a factor. The base of the lake-duck penis is covered with spines, yet the tip is soft and brush-like. Before ejaculation, drakes probably use the penises like bottle-brushes to remove sperm stored in the oviduct by the female's previous consort. The larger the bottle brush, the more effective it will be, clearing way for the drake to father ducklings.
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According to one paper, water-bound reproduction may in part account for this extraordinary extremity:
Quote:
http://mercury.bio.uaf.edu/~kevin_mc...uk-117-820.pdf
The presence of a well-developed penis in many dabbling and diving ducks may derive in part from their tendency to copulate in the water (Lake 1981). Geese, which tend to copulate on land, typically possess much smaller penises, even though their overall body size is larger (Coker 1998). Another probable, but not necessarily exclusive, explanation is that large ornamented penises have evolved in response to sperm competition within the female reproductive tract, such that males with larger penises achieve greater reproductive success than others (Waage 1979, Thornhill and Alcock 1983, Eberhard 1985). Species that experience greater sperm competition are expected to possess larger penes that may increase the probability of successful fertilization (Birkhead and Møller 1992, Briskie andMontgomerie 1997)
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Trying to formulate an apt pun, but it seems the muses have forsaken me... just pretend this spot was filled with a hilarious duck pun
