Animals in which penis size does matter

Does the penis size? This is a question we have all asked ourselves many times, but there is usually no consensus on the answer. Perhaps the most conciliatory thing to say would be no. And perhaps it is so among humans, because the reproductive success is not usually linked to the size of the limb. But in other animals it is different.

There are species that have had to develop larger penises for all sorts of reasons. Some are directly related to the fact that attracting females for mating. But others are rather more bizarre. At the same time as fascinating of course.

These are six of the most striking examples, though there are many, many more.

Ducks that change penis size according to circumstances.

Aythua affinis. Basar (Wikimedia Commons)

Generally, the penis size in humans is no longer a determining factor when it comes to reproduction. Perhaps it was at the dawn of the species, but nowadays much more value is placed on qualities such as knowing how to wash your underpants.

There are large differences in penis size between ducks living alone with a female, or in groups with many males and few females

But there are still animals whose males need showy genitalia to attract females. This is generally related to a greater amount of semen and, therefore, a greater reproductive success. This is the case for some ducks, such as the ball duck (Aythya affinis) and the ruddy duck (Oxyura jamaicensis).

It was discovered in 2017 by evolutionary biologist Patricia Brennan whose results can be read in a study published in The Auk: Ornithological Advances and reported by Nature. In that work, she shows the differences observed in the penis size in ducks that lived in pairs or groups with many males for a single female.

He found that they had the ability to adapt the dimensions of their limb. That is to say, in the first case, this reached what would be considered a normal sizecompared to other ducks. However, in those that lived in groups, the existence of competition with other males caused his penis to grow much larger.

But, beware, here the females also have a lot to say. And in a previous study, carried out by the same scientist, it was seen that their genitals have evolved to prevent the access of those males that try to to force copulation. This conformation allows them to be the only ones who choose the male, since they must place themselves in a very specific position so that the penis can penetrate their vagina and, in addition, deposit the sperm near the eggs. They exhibit their attributes and she chooses, without pressure. As it should be in all species.

Chimpanzees versus gorillas

Gorilla, penis size, animals

The case of the primates is extremely varied, for they reproduce under very different circumstances. It can be clearly seen by comparing the gorillas (Gorilla gorilla) and the chimpanzees (Pan troglodytes).

With regard to the penis, curiously enough, the gorilla’s penis measures about. 3 centimeters in erection, whereas that of the chimpanzee reaches 7 centimeters. Proportionately to its size, the second one is much larger. And it is precisely because of their constitution that gorillas do not need a huge limb. Their competition between males is rather physical that’s why they are so strong and big. They don’t need a big penis to impress the female.

Chimpanzees, on the other hand, do. Although more than the size of the penis, what makes the difference in these apes is the size of the testicles. This could be explained by the sperm volume hypothesis, which indicates that some species show females that have a larger amount of semen to fertilize them, showing testicles of large dimensions. A large factory must generate a large product, hence why this display is so important.

From penis size to staff size

penis size, animals

The crozier is the penis bone. A structure that has been lost in some species, such as humans, but is still found in many others.

The reason why some animals have retained it and others have lost it as they have evolved is unclear. There are many theories, one of the most important being the. competition between males. In fact, it has been shown that in animals like wolves (Canis lupus) and dogs (Canis lupus familiaris) which in the wild are more territorial and can be in competitive situations, the staff has deep urethral grooves and insertions in the bulb of the glans penis. This, it seems, may help them to remove the semen of other males who have previously copulated the female. Thus they compete for reproduction, but without the need to fight.

The hermit crab: a large penis so as not to lose its home.

penis size, animals

The case of the hermit crab (Coenobita spp) is one of the most curious animals as far as penis size is concerned.

A longer penis enables them to copulate without leaving the shell

He described it in 2019 Mark E. Laidre of the Dartmouth College in a study published in the journal of the Royal Society. In it, the cases of several of these crabs are analyzed, comparing the size of their penises with the size of their penises. value of their shells.

They are special animals, because they literally carry their house on their backs. But not like snails, which have it built into their bodies. They can come and go. Normally to copulate with a female they come out, but in the meantime they leave their home unprotected so it could be stolen by another animal. And this is where you see the importance of penis size.

In research prior to the publication of his study, Laidre found that those crabs with more valuable shells have longer penises. The reason for this is that they can extend them outward to copulate. This way, they don’t have to leave the house to have sex. They reproduce and don’t lose their home. A real win-win situation.

The flatworm and his sword fight.

penis size, animals

The case of some animals hermaphroditessuch as the flatworms of the species Pseudoceros bifurcus is particularly interesting.

Being hermaphrodites, they compete with their penises to try to impregnate each other…

Being hermaphrodites they have genitalia. both female and male so that they can fertilize, but also be fertilized. Roughly speaking, you could say that they can act as males or as females. But they all want to be males. And no wonder. Here it happens as in so many other species. The male fertilises and that’s the end of his job. The female has to invest a lot of energy in the whole reproductive process.

That is why, when two specimens are considering copulation, they both pull out their penises and try, literally, to stick it in to the other. The process is almost a sword fight, in which the size of the penis is quite important. And also in which both usually end up quite injured. But especially the loser, who in the end not only has to deal with injuries, but also with pregnancy. Surely, these animals should learn from ducks.

Let yourself flow like barnacles

penis size, animalsRaresvent (Wikimedia Commons)

The barnacles (Pollicipes pollicipes) are also hermaphrodites, but rather more civilized than flatworms. Actually, they are somewhat more like ducks. However, in this case the size of the penis does not depend on the competition, but on the waters in which they live.

Barnacles adapt the size and shape of their penis to the situation of the waters in which they live.

And not only the size, but also their shape and consistency. In general they have a fairly large member. In fact, in proportion to the body, it is considered the largest that has ever been measured, for it can reach eight times the size of their body.

This allows them to find and fertilize distant neighbors, without separating from the rocks to which they live attached. But of course, the process can be disturbed by the swaying of the water. So the shape of their penis will vary depending on where they live.

Specifically, in calm water they will have penises… longer and thinner…but when there are many waves they adapt to the situation and exhibit penises shorter and more robust which allow them to reach nearby rocks without being deflected by the undulations of the sea. Another fascinating case of sex adapted to the circumstances.