Few animals have such a friendly snout as the alpaca. But that’s not the only thing that makes the animal special. The male is also the only mammal in the world that directly inseminates the uterus during mating. Biologists from Mount Holyoke College in the US discovered this when they studied the reproductive organs of several female alpacas shortly after they had been slaughtered. It showed that the male alpaca pushes his penis all the way into the uterus to fertilize the female.
Long, thin penis
Previously, breeders of the animals noticed that the male thrusts his genitals very far into the female. They also knew that the animal has a particularly long and thin penis, a so-called fibroelastic penis. There are two types: the muscovascular penis like humans have, but also, for example, a horse and a cat. It needs a lot of blood supply to get an erection. A fibroelastic penis, which you find in a bull, ram or pig (and therefore the alpaca), requires much less blood supply and becomes much longer during an erection.
The alpaca’s penis is even more special: it has a hard top of cartilage and almost looks a bit like a spear. The alpaca thus deposits the sperm directly into the female’s uterus, instead of first entering the vagina, as other male mammals do.
Bleeding uterus
The researchers came to this conclusion when they went to an alpaca farm where the animals are bred for their meat. They dissected several females that were killed shortly after mating with a male. In doing so, they discovered that the alpacas were bleeding profusely from various parts of the reproductive tract, from the hymen to the cervix and the uterus itself. They found the same thing in all other females that had recently mated. And for extra confirmation, females that had not recently been visited by a male did not bleed at all.
More chance of fertilization
According to the researchers, this is evidence that males thrust their penis all the way into the uterus during mating. The females probably don’t like that very much. Hard thrusting with the sharp penis not only leads to bleeding, but also to inflammation in the reproductive organs. However, that is good for the chance of success. The way the alpacas mate increases the chances of successful fertilization and pregnancy. The inflammation would even help the fertilized egg to implant in the uterine wall.
