You should check out all of my SiBlings' Friday Blogging practices, then come back here for a new edition of Friday Weird Sex Blogging. Last week you saw an example of a corkscrew penis. But that is not the only one of a kind. See more under the fold (first posted on July 14, 2006)...
Some birds also have spiral tools. For instance, see this 20-cm penis of an Argentine lake duck (Oxyura vittata) (from this paper: The 20-cm Spiny Penis of the Argentine Lake Duck (Oxyura vittata) (pdf)):
The same author, Dr Kevin McCracken of the University of Alaska, Fairbanks, later found an even longer one in the same species. It was 42.5cm long and the paper was worthy of publishing in Nature: Are ducks impressed by drakes' display? (pdf)
The male may use the brush-like tip of its penis to scrub the sperm of previous mates from the female's oviduct. The press coverage was characteristically spectacular: Found! The longest bird penis ever:
"It's a fascinating bit of anatomy they've discovered here. It really is unusual," commented bird mating expert Dr Raoul Mulder from the University of Melbourne.
What a great opener at a cocktail party! What do you do? "I am a bird mating expert!"
Dr McCracken and colleagues speculate that the giant penis may be an example of 'runaway' sexual selection, where female preference drives male anatomy to ever-greater extremes, as in the peacock's tail.
Dr Mulder believes this may be a bit of anthropomorphising, however. "I'm not fond of the 'nudge nudge, wink wink' comments by the authors," he said.
I am with Mulder on this one. But what does agent Scully think?
The journalist, of course, could not help but introduce some more double-entendres:
The authors write that this species is "promiscuous and boisterous in their sexual activity", which means that there is likely to be stiff competition by drakes to be the father of ducklings.
In most bird species, there are no copulatory organs and the two animals just touch their cloacal openings and exchange sperm. The female is capable of storing sperm and choosing which male's sperm to use to fertilize her eggs. The species which do have penises, thoughs, include some ducks and swans that engage in what appears to the human eye to be "forced" copulation.
The Argentine lake duck, although a holder of the Guinness World Record for length is not the only bird with a penis, or for that matter a bird with a most unusual penis (or a similar organ in a similar place with a similar function). Though only about 3% of bird species have a copulatory organ, some are downright weird.
Bigger birds, including ducks, geese, swans, ostriches, cassowaries and kiwis continue to have a penis. This penis is generally spiral in form so that it can reach the female sex opening, which lies to the left in the cloaca. The rhea has an extrudable organ. As waterfowl sometimes copulate in water, the penis helps ensure that the water does not wash away the sperm. The Australian blue duck, for example, has a penis so large that when it finishes copulating the bird has to turn on its back and stuff its penis back into its cloaca.
The male cassowary has an organ that looks remarkably like a penis. This phallus does not discharge semen internally. It is "invaginated," having a tube-like roll of tissue that opens at the tip of the "penis", but is not connected internally to the male reproductive organs. The male's vagina-like cavity is used to retract the phallus by turning it "inside out" (so the non-erect "penis" resembles the finger of a glove pushed inward). While the male inserts his erect phallus into the female during mating, he ejaculates semen through his cloaca, an orifice at the base of the phallus that also doubles as the bird's anus and urinary organ.
Female cassowaries mate, lay eggs, defecate, and urinate all through the same orifice, the cloaca, which is exceptionally large in this species, being capable of passing eggs weighing up to 1-1/2 pounds. All female cassowaries also have a phallus, which is essentially identical to the male's phallus in structure but smaller. The "female phallus" is sometimes referred to as a clitoris, but it would be equally valid to speak of a "male clitoris," since the male cassowary's "penis" is not an ejaculatory organ. The cassowary's genital anatomy exhibits a juxtaposition of "masculine" and "feminine" traits: both sexes possess a penis/clitoris and also have another genital orifice that doubles as an anus.
Nature (Vol 399, 6 May 1999) states that male buffalo weavers (Bubalornis) have a false penis or phalloid organ and show intense sperm competition, where unrelated male coalitions defend multiple nest chambers. The organ is a stiff rod of connective tissue, lying anterior to the cloaca. It lacks ducts and is not homologous to the penis in other bird species. Females have a much smaller phalloid organ. The male's organ seems to be a stimulatory organ. After protracted copulation, the organ generates an orgasm-like state in males, unlike other birds.