Nature has had billions of years to experiment with reproduction, and it’s come up with some pretty bizarre ways to mix genes. While it’s a little taboo, here’s some of the weirdest solutions that have evolved over the years. Ladies and gentlemen, the weirdest penises in nature.


Coyotes are native to North America and play an important part of the ecosystem. They’re very social animals that travel in packs and have a highly advanced communication system. And they also have a (gesture) BIG, LONG… history of intermingling with wolves.

Maybe it’s this inter-species scootelypooping that’s the reason that coyotes, though smaller than wolves have a (gesture) MASSIVE impact on the environment.

This video is not about coyotes, but longtime viewers know what I’m referencing here.

Yes, in the video where I celebrated a million subs on this channel, my team of clones recommended a few video ideas…

We’ve already done a video on one of those topics well, here’s another. (beat) Sort-of.

(play clip where I say, “Is there enough about coyote penises to make a video,” and then “you have no idea”)

Turns out no, there’s not.

Not about coyote penises specifically but penises in general… Now that’s a subject that goes DEEP.

Because sexual reproduction is how we all got here. The mixing of genes has been essential for genetic diversity and evolution, and nature has spent billions of years exploring different ways of doing that.

So today let’s take a look at the various methods nature has used to insert tab A into slot B. This… could get weird.

By the way, it probably goes without saying but to all of you who send me emails saying you like to watch my videos with your kids… Maybe sit this one out. (beat) Or don’t. They’re your kids, mess them up however you want.

Let’s start by stepping WAY back and getting a handle on the fundamentals of sexual reproduction so we can understand how it got so weird.

In sexual reproduction, a haploid female gamete (egg cell) fuses with a haploid male gamete (sperm cell).

The fusion creates a diploid zygote. Diploid means the chromosomes are paired.

All this creates an organism that is genetically distinct from the parent organisms.

On the other hand, asexual reproduction doesn’t involve gametes, and the offspring is a clone of a parent. Which is probably simpler.

So why does nature go through so much trouble for this? Or maybe a better way to put it is to say why has this method of reproduction been so successful despite all the extra energy it requires.

One advantage is that it helps ensure a particular species’ chromosome number remains the same across generations.

And another advantage is that it increases genetic variation and expands the gene pool, which allows the species to adapt and evolve over time.

There are two types of sexual reproduction:
– Syngamy – internal or external fusion of haploid sex cells; most common type of reproduction in multicellular sexual populations
– Conjugation – temporary fusion to exchange micronuclear material; often seen in single-cell organisms

Eukaryotes were the first organisms to engage in asexual reproduction around two billion years ago.
(on screen: Eukaryotes are single-celled or multicellular organisms whose cell includes a distinct, membrane-bound nucleus.)

Internal fertilization among vertebrates is much more recent on the evolutionary timescale.


Gotta start with the ducks.

So first of all most bird species don’t have penises at all. Both sexes have a cloaca and when one bird loves another bird very much, the male will rub his cloaca against the female’s cloaca and pass sperm from his cloaca to hers.

Heterosexual scissors, if you will.

But ducks don’t do scissors. They use a different kitchen utensil. Corkscrews.

When ducks mate, they bond for a whole mating season, but rival males will often violently force themselves onto females.

Don’t know if I need a trigger warning here but yeah… Nature can be a little rapey.

So over evolutionary time, female ducks developed elaborate vaginas with dead-end cul-de-sacs and spirals.

Consequently the male ducks developed weird, corkscrew penises with ridges and backward-point spines that help them deposit sperm further into a female than a rival.

So if you say two ducks are screwing, that is a quite literal statement.

And as if male duck d*cks weren’t weird enough, turns out they are both growers and showers.

Male ducks can respond to sexual competition by growing an extra-long penis or a nub of flesh on the end of their penis.

According to a study by Patricia Brennan of Mount Holyoke College, when a male is alone with a female it would grow a normal-sized penis.

But if other males were around, they grew larger penises so they could show females that they could deposit sperm further inside her.
(Caption under name: assistant professor of biological sciences, Mount Holyoke College, Massachusetts )
(Source: The Auk: Ornithological Advances, 2017)

“So evolution must be acting on the ability to be plastic—the ability to invest only in what is needed in your current circumstance,” Brennan told Scientific American in 2017.

And the current circumstance of ducks apparently requires a giant corkscrew penis.

Sea Slug

Something that stands out when looking at the world of sexual reproduction in nature is that it’s not just about depositing sperm, it’s about keeping other creatures’ sperm out.

Ducks managed this with corkscrews, sea slugs have a different strategy.

The Chromodoris reticulata is a type of sea slug found in the Pacific Ocean.

Researchers believe it may be the first creature known that can have sex repeatedly with a disposable penis. No, it’s not just a great King Missile song.

Sea slugs are also known as nudibranchs and are believed to be “simultaneous hermaphrodites.”

In other words, they have both female and male organs they can use at the same time. So when two sea slugs mate, the penis from one slug fits into the female opening of the other slug, and vice versa. So they can essentially impregnate each other.

I wonder what the abortion issue would look like if that were true for us…?

But anyway, Japanese researchers noticed something interesting and published their findings in Biology Letters in 2013.

They watched the slugs mate 31 times. After the… (stare into space) I’m sorry, I just had so many jokes go through my head I disassociated.

That was somebody’s job. To watch the two horniest sea slugs alive just rail each other over and over and over and over and over…

I don’t care how bad your job is, that guy’s job is worse.

And apparently while watching these two nymphomaniacs going at it, he noticed that after each act, they shed their penises. Just snapped them right off in each other. Then he wrote a report about it. Went home to his spouse.

Spouse (cutting up food on the plate): So, how was work today?

Researcher (dazed with a drink in hand): I watched two sea slugs f*ck 31 times.

Spouse (unfazed): Yeah, how’d that go?

Researcher: They snapped their d*cks off up there.

Obviously, to do that 31 times means they need to be able to regrow it, which they did, within 24 hours. In fact, they could mate three times in succession with each act separated by about 24 hours.

And the slugs’ penises also had backward-pointed spines on them, so the prevailing theory is that during the first act the penis may be used to remove sperm left by competitors.

The second penis is used then to inject the slug with another dose of its own sperm. This helps ensure their genes are passed on.

As for the other 29 times… Well, slugs are sluts.


From animals that lose their penis to animals that just… become the penis.

The male anglerfish has one goal: To attach itself to a female anglerfish and remain with her for the rest of his life.

But this isn’t some romantic movie where the characters make out in the rain as the credits roll, this is a love story written by David Cronenberg.

Go figure this fish would have the creepiest sex imaginable.

So what happens with the anglerfish, is that when the male finds a female he likes, he approaches her, says hi, and then like… bites into her side. Forever.

He basically attaches himself to her and over time his circulatory system merges with hers, he basically fuses with her and then his eyes, fins, and almost all his internal organs degenerate.

What’s left is a sexual parasite that provides sperm for the female whenever she demands. He’s basically just a sperm pump.

Female anglerfish are significantly larger than their male counterparts, and a female can collect up to eight males fused to her body.

Males! Collect them all!

So yeah, this is super weird but of course there’s a reason for this, and that reason is food.

At the depths these fish are swimming in, food is scarce. So this helps not only guarantee a mate for life, but also helps half the resources needed to survive.

It should be noted not all anglerfish do this, there are around 300 anglerfish species, but only about 25 species do it this way.

By the way, this is called “sexual parasitism.” They’re literal sexual parasites.

Again… So many jokes…


Eels had a moment in the last year or two in the “weird science” circles. Which is a thing I just made up.

There were a lot of social media posts and videos going around about how nobody really knows how eels reproduce.

Because we’ve never seen them do it. And they don’t seem to have any genitalia.

That of course is not true, scientists do know how they do it and they do have genitalia, you just have to dissect them to find it.

But that doesn’t change the fact that it is still very, very weird.

First of all, they have a complicated life cycle, starting as larvae drifting in the Sargasso Sea, which is in the middle of the Atlantic Ocean.

The larvae look like transparent willow leaves, and they travel along ocean currents. The American eel drifts westward, and the European eel drifts eastward.

By the way we have no idea how they know which way to drift. But they apparently just do.

When they reach land, they become glass eels. And then they do something that very few animals can do, they move into freshwater, and become freshwater eels. Which are known as yellow eels.

These are the eels most people eat, by the way.

And then these yellow eels live like this for a REALLY long time, up to 85 years. Assuming it doesn’t get eaten.

But whenever an eel decides it’s the end of its life, it goes through a fourth transformation and turn into silver eels.

By the way, this is why it was so hard to figure out how they reproduced because for a long time, they thought these were 4 separate species.

So it becomes a silver eel and swims back out to the Sargasso Sea, where they started from. This can take up to a year, and their bodies continue to change along the way.

They don’t eat for the whole journey, in fact their stomachs dissolve, its eyes change and it develops sexual organs.

So after living up to 85 years, they finally become sexually mature. And by the way, if they don’t swim out to the Sargasso Sea, this doesn’t happen. They can live almost indefinitely in the yellow eel stage.

Maybe that’s the key to immortality, just don’t grow sex organs.

But why the Sargasso Sea? What’s so great about that spot? And how do they even know how to get there? (beat) No, seriously, I’m asking, nobody seems to know.

Some theories include water temperature and salinity for why they go there, and scent and electromagnetic fields for how.

Also, an eel’s sex is determined by its environment and not genetics. It is neither female nor male when it hatches.

Anyway once they reach the Sargasso Sea, that’s where they mate and lay eggs, its believed they reproduce externally with clouds of sperm fertilizing free-floating eggs. But… It’s never actually been seen. It is still a bit of a mystery.

My bet is that it would be weirder than that because of course it would be.

This is a short list. There are so many other animal penises we could have explored. Some of these include the
– Echidna, with its four-head penis
– Dolphin, with its penis that can grab, grope, and swivel like a human hand
– Barnacle, whose penis is nearly eight-times its body length, which it uses to reach out to nearby mates
– Insects of the Neotrogla genus, where the males have a vagina-like pouch with sperm, and the females have a penis-like organ that penetrates the male and collects the sperm
– And the argonaut octopus, a cephalopod whose penis detaches itself from the creature’s body and swims around looking for a lady.

But of course a cephalopod would be on this list because they are some of the weirdest creatures on the planet which is why I made a whole video on them which is the pinnacle of science entertainment that is so important to the history of humanity that it should have been imprinted in the Voyager golden record… wait did Jason write this one? Ah, he got me. He got me again. Little scamp.

But anyway, sexual reproduction comes down basically to taking genetic material from a male and a female and mixing them up. And as we’ve seen, there’s no one way to do it.

No matter how kinky you think you are, nobody’s as creative in the sex department than nature.







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