Mallard
Anas platyrhynchos
13.2 cm
Length of the manually, fully everted, formalin-fixed phallus, measured with dental floss laid in the sulcus from base to tip
Corkscrew, Spiny
Fully everted and measured along the sperm groove, the phalluses of two mallard drakes averaged 13.2 cm. They coil anticlockwise, while the female's vagina coils clockwise.
Sources
- Brennan P.L.R., Prum R.O., McCracken K.G., Sorenson M.D., Wilson R.E., Birkhead T.R. (2007) Coevolution of male and female genital morphology in waterfowl. PLoS ONE 2(5): e418 doi:10.1371/journal.pone.0000418
- Brennan P.L.R., Clark C.J., Prum R.O. (2010) Explosive eversion and functional morphology of the duck penis supports sexual conflict in waterfowl genitalia. Proc. R. Soc. B 277:1309–1314 doi:10.1098/rspb.2009.2139
- Johnsgard P.A. (1978) Ducks, Geese, and Swans of the World. University of Nebraska Press. Tribe Anatini chapter (UNL DigitalCommons edition) link
Drawn from
- Brennan et al. 2007, PLoS ONE, Fig. 2D: Mallard male phallus (bracketed, coiled, ridged, tip curled) beside the female's coiled vagina; 2 cm scale bar
- Brennan et al. 2010, Proc R Soc B, Fig. 1a: Pekin duck (domestic mallard) phallus, lateral view: anticlockwise spiral, sulcus spermaticus, tip (a. ph.); 2 cm scale bar