I went to an endocrinology conference last week, and one of the talks was about the bizarre hormones and sexual behavior of the spotted hyena, and I just *knew* everyone on this group would be interested.
It turns out that in a pregnant spotted hyena, the placenta churns out amazing amounts of androgens (male hormones, to oversimplify a bit), such that no matter what sex the fetus is, it ends up with totally masculine external genitalia. This means that all female spotted hyenas have penises, just the same size and almost the same shape as the males (tiny difference in the head shape -- in fact, that's the only way to figure out what sex your spotted hyena is. Penis with pointed head = male. Penis with squarish head = female). This is an impressive penis, too -- looked about a foot long or so from the photos. The hyenas are constantly having erections and waving their penises around in bizarre social dominance displays. As it happens the females are larger and more dominant. The females also have a scrotum, but it's empty -- their ovaries are up in their body as usual. The ovaries apparently don't mind the massive androgen-dosing during development, and in fact the ovaries happily churn out even more androgens throughout the female's entire life, keeping her nice and masculinized.
Okay, here's where it gets fun. You've got a female whose uterus connects to the urethra, which goes down through the penis. See the problems?
Problem #1: When spotted hyenas have sex, the male has to put his penis *through* the female's penis. Luckily hyenas have those retractable-type penises, like horses, but still it's pretty awkward. We saw a video of a male hyena attempting to have sex with a virgin female, and he had to sort of squat down between her hind legs and thrust upwards at a really weird angle, until suddenly she yelped, spun, and nearly bit his nose off.
Problem #2: (the biggie) When a female gets pregnant, she has to give birth THROUGH HER PENIS. We saw another video (really, this was a *great* talk!) of a female giving birth for the first time. First-time mothers only have one cub, and the cub comes out of the vagina, gets shoved around the pelvis, between her hind legs, and into the penis, and then gets *jammed* up against the inside of head of the penis. A newborn cub is the size of a Coke can. (Compare to the normal erect penis, which looked about 1-2" diameter.) This poor female was crawling around miserably, licking at her grotesquely swollen, almost black penis, until suddenly POP! the head of the penis *ripped* *open* and the cub came out. YOWZA! (The whole audience sort of whimpered at this point.) Many first-time mothers die of infections and other complications; many first-time mother's cubs are stillborn or die soon after birth, apparently from being jammed up for too long. Apparently the penis heals with the head still ripped open, making subsequent births a lot easier. Subsequent births are usually 2 or 3 cubs, and newborn cubs of the same sex immediately try to kill each other, by biting each other on the neck and back (we saw another video)...it's a strange species, what can I say?
All this is only true of the *spotted* hyena, not of other hyena species. The work was primarily done at Berkeley, which maintains a colony of spotted hyenas.
I *knew* you'd be interested! (And you probably thought scientific conferences were always boring.)