I feel like humans think that we have the  market cornered on weird ways to have sex   just ask the internet.

Actually, don't ask the internet,  especially if you're at work right now. But despite all of the  fetishes and bizarre role play we work into our bedroom activities, we just cannot compete with  the rest of the animal kingdom.

For every creative sexual idea,  someone, somewhere has partaken in, there are mating rituals a million times  weirder out there in the wilderness. So in the name of science, let's learn about them. Here are the ten weirdest ways animals have sex.

According to us. [♪ INTRO]

One penis. One vagina. Pretty standard sex stuff as far  as most mammals are concerned.

Marsupials, however, are not  bound by such limitations. Now, we already know marsupials don't follow  the same reproductive rules as other mammals. Their babies are extremely immature at birth,  and finish their development in a pouch on the outside of the mother's  body instead of on the inside, but they also do sex a little differently.

Female marsupials have an extra  set of reproductive organs. That's right, they've got two uteri,  two cervixes, and two lateral vaginas, and yeah, I said uteri. They also have a median vagina.

So  technically they have three vaginas. So what's the median vagina for it? Well, the lateral vaginas receive the sperm, and the median vagina is the birth canal.

And the males have pretty weird junk, too, though they don't have two penises per se. Many male marsupials have  forked or bifurcated penises The reason being that this allows for the correct  placement of sperm at the base of both vaginas  and different marsupials have different  ways of using those extra sex organs. The Tamar wallaby, for example,  has one baby at a time, which means only one uterus is in use.

Other wallabies do it a bit differently. The swamp wallaby, for example, has an estrus cycle that is  shorter than its gestation time, so it goes into estrus before it gives birth, then becomes pregnant with another fetus while still pregnant with the first fetus. The second fetus then enters a  state called embryonic diapause, which means that it basically just stops  developing until after the first one is born, like way after.

In fact, the younger fetus doesn't begin  developing until nine months later. After the older one leaves the pouch. So a female swamp baby can literally  be pregnant for its entire adult life.

All right, we're not supposed  to be fans of our next creature because bedbugs are horrible little insects  that feed on us while we are sleeping, instead of just being brazenly parasitic  and proud of it like the noble mosquito. But I mean, after hearing  about bedbug mating behavior, you might almost feel sorry for them. The mating strategy they use is  called traumatic insemination, and it's called that, for  the reason you might expect, the male bedbug uses his genitalia to literally  punch holes in the female's body cavity, and then he inseminates her through the holes.

The female does, in fact, have a genital tract, but the male just doesn't bother  with that sort of romance. The genital tract of the female bedbug  is just for egg laying, nothing more. There are various theories  for why bedbugs evolved this, extreme and awful sounding mating strategy.

In bedbugs. The last male to mate  with a specific female is typically the one who gets to pass his genes along. So traumatic insemination may have  evolved as a way for males to bypass female adaptations that limited  how much action they could get.

But some scientists also think  this way of making new bedbugs has larger benefits for the species. Namely, it makes the females  run away from the males and take up residence in new places like hotels and motels and your  waiting room, couches and luggage. So the bedbug mating strategy  doesn't just suck for the bedbugs.

It also sucks for the rest of us. Thanks, nature. If traumatic insemination  isn't weird enough for you, allow me to introduce you to the echidna.

Also known as the spiny anteater. It's a monotreme and monotremes  are mammals that lay eggs like the platypus. And not to be outdone by the marsupials, which, as you recall, have double headed penises, the echidna has a four headed penis, though only two of them can  become erect at the same time.

Structurally, the male echidna  has a urethra with four branches, one for each head. It also has two corpora spongiosa, the column of spongy tissue  that surrounds the urethra and contains all the blood  vessels that produce an erection. Blood flow is directed to only  one corpora spongiosa at a time, which keeps two of the branches open, allowing  for both to ejaculate at the same time.

This configuration seems to allow the  echidna to alternate between penis pairs every time it gets busy. Speaking of getting busy, the Antechinus resembles a mouse,  but it is actually a marsupial, so it has to live up to the marsupials  reputation for weird reproductive strategies and the mouse's reputation for proliferation. And it does a very fine job  of both of these things.

In fact, the Antechinus has  a three week mating season, and the male makes excellent use of all 21 days Blindly humping every female  in sight until it dies. Literally dies. And this is not one of those  like my girlfriend ate me things like what sometimes happens  with male black widows.

Scientists aren't exactly sure why  this happens, but it appears that the male Antechinus dies just from enthusiasm, perhaps because he doesn't take time out from  all that lovemaking for less important things like eating. According to some reports, all of that  sexual activity can sometimes even make them Lose all of their hair and go blind, just like your grandma warned you. This is just the males, by the way.

Otherwise it might be a real  problem for the species. Females typically get through mating season intact and end up living twice as long as  their horny little counterparts. Next up on our list is the fan fin sea  Devil, which is a type of anglerfish.

You may know anglerfish from  that one scene in Finding Nemo, but Finding Nemo is a kid's movie, so you  may not know what these guys do in the dark. And as you know, down there where  they live, it is super dark. So the male anglerfish looks for a mate  based on the smell of her pheromones.

And because it's dark and the male is  much, much smaller than the female, Once he finds her, he has to latch onto her. And he does this very literally by fusing with her and not like in the poetic sense of that word, if there is a poetic sense of the word, no, in the literal sense of the word, he literally fuses with her until  he becomes a part of her body like a leech, but one that  she can never pluck off. He gets his nutrients from her and  even shares her circulatory system.

In return, she gets access to  a bottomless supply of sperm, which seems kind of like an unfair trade. But no one ever said nature was fair. Before we get to number six,  which I promise is very weird, we're going to have a little cut to our sponsor.

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If you’d rather show your support as an OG SciShow viewer you can opt for the classic SciShow keychain. You can shop for those items and more at complexly.store/scishow or at the link in the description. Now, this little water bug is  also called the singing penis because it uses its penis as a violin for real.

It rubs its penis against its  abdomen as a way of serenading the ladies. And in case you're thinking that this  is maybe sort of similar to a dude standing outside his beloved's  window with a boombox, yeah, it's kind of like that. If the boombox was turned up  really, really loud and was a penis, the penis violin is about 99dB loud  or about as loud as a lawn tractor, so there's no turning it  down for the singing penis.

The neighbors are always  going to know what he's up to. As romantic as a singing penis is, the  red velvet might goes even further. The male woos the female of his dreams  by planting a love garden for her.

Not with flowers though. With his ejaculate. First he leaves silken trails  for the female to follow.

You know, kind of like a trail of rose  petals, only there's no champagne at the end. Instead, the trails lead to these little balls of  sperm that he's dropped on twigs or plant stems. Evidently, the female follows the  trail, sees the sperm ball and goes, Oh, how lovely, and then sits on it, because why wouldn't you?

Suddenly I feel less inclined  to take up gardening. Maybe because our next creature  can be found there too. Land Snails are hermaphroditic, usually both sex partners are inseminated and both partners lay eggs.

But that's actually not the most  unusual thing about land snail sex. Land snails shoot love darts at each other, kind of like Cupid's arrows, only there is no adorable cherub on the other end. There's actually a more scientific  name for these, gybsobelum, but scientists do usually call them love darts.

The purpose of the love darts  isn't super well understood, and not all snails use them in the same way. Some leave the dart behind in their  partner, while others retract it. In the common garden snail, both partners  shoot a dart before exchanging sperm.

The leading theory is that the  love dart contains an allohormone that prevents their partner's  body from digesting the sperm, and that may help ensure that as  many eggs as possible are fertilized. For snails, love darts are a sort of foreplay  thing that both partners seem to be into, but other species are a little bit more combative. Like flatworms, these animals engage in penis fencing, and they don't even have  to be fraternity brothers.

In fact, they aren't even sure if they're  male or female until the match is over. In this ultimate showdown of masculinity, it is the outcome of the battle that determines which one gets to be the sperm donor  and which one gets to be the egg holder. Here's how this works.

They try to stab each other with their  penises, which we've seen before. It's traumatic insemination all over again. There's also pairing, just like in fencing, with the goal of not getting  stabbed with the other guy's penis.

The battle ends when one of them  succeeds in stabbing the other Again with their penis. The winner provides the sperm  and the loser provides the eggs. So, like, why all the conflict?

Why can't they just have, like, a romantic evening where they discuss their  common and shared interests and then they decide which one seems  more in touch with their feminine side? Well, laying eggs comes  with certain fitness costs, so this may be one reason why the  worms would rather be the sperm donor than the egg layer, though in laboratory research, it's worth noting that both worms  eventually ended up inseminated despite their sincere efforts to  win the battle of the penises. And finally, we reach the  weirdest creature on our list the octopus.

Male octopuses have an arm penis. Specifically, this is a modified  arm called a hectocotylus, which the male uses to inseminate females in some genera, like Argonauta, the  males are a lot smaller than the females, like one eighth of the length of  the female and 1/600 of her weight, so male Argonauts have a special trick they can detach their hectocotylus. Yes, a detachable penis, just like that song from the 90s that  I remember and you probably don’t.

The detachable arm penis  even behaves autonomously, exploring its environment, avoiding danger. And of course, protecting its  all important penile filament. It's not completely clear why the male argonaut has evolved this reproductive strategy, or what happens afterward.

He might be able to regenerate his arm penis, or maybe he just dies after he's detached it because when the choice is between  your life or your arm penis just die. Perhaps most surprising of all,  this list is nowhere near complete. I'm stopping at ten because you  don't have all day and neither do I.

But I'll leave you with this thought. Even though these reproductive  strategies may seem a bit strange to us, like one penis, one vagina types, they have helped these animals  survive and thrive for a long time, which is further proof that  nature doesn't have norms. What happens is whatever works, be it between marsupials or snails or flatworms, Who are we to say that it's weird? [♪ OUTRO]