Have you ever read an awesome science fact, only to do a little bit of digging  and learn the source blew things way out of proportion?

I’m gonna let you behind the  SciShow scenes for a bit. Our script editors are always on the  hunt for weird and complex science stuff.

Last year, one of them was  reading a book about beavers, and 150-odd pages in, the  author suddenly mentioned there’s a type of octopus off the  coast of Australia that, quote, “builds the equivalent of a walled medieval city.” Which if true, would probably  make for a good SciShow episode. As you may suspect, that quote turned out to be a gross mischaracterization of reality. And this book is not the only  source to have gotten a bit… let’s say overenthusiastic… about what scientists actually uncovered.

But our script editor was  undeterred by this setback. And with a little more research, it was clear that these  structures are still super weird, and reveal just how complex  the octopus lifestyle can be. So let’s break down what’s really  going down in these octopus cities. [ INTRO MUSIC ] As much as we’d love to animate  an octopus gripping medieval tools with their many tentacles, and  shouting things like "forsooth!" and "the devil take thee!", the real animals behind these  not-actually-cities look like this: This is Octopus tetricus.

Also known as the gloomy octopus, because its large, sad eyes  give it a sort of emo vibe. Until recently, scientists thought it was a solitary creature, preferring to hang out in  its bedroom alone listening to My Chemical Romance and nessa  barrett until three in the morning. But then, they started discovering  sites where gloomy octopuses gather.

And for context, all of this  is taking place in Jervis Bay, which is about a two-hour drive  south of Sydney, Australia. The first site was discovered back in 2009, and researchers nicknamed it Octopolis. It’s centered around a 30-centimeter  long Unidentified Sunken Object… that’s definitely something humans made, but  that’s pretty much all we can say about it.

And that’s okay, because the real star of the show  is the horde of scallop shells and other debris that the  octopuses have collected around it, and used to construct their dens. Then in 2016, divers found Octlantis, a second site just a few hundred  meters away from Octopolis. Here, gloomy octopuses have  surrounded three patches of rock with similar piles of debris, including human things like beer  bottles and lead fishing lures.

The fact that Octlantis wasn’t seeded by a human-made structure  is actually pretty important from the science side of things. Because It shows Octopolis  wasn’t an unnatural fluke that only happened because of some  accidental outside human influence. At both of these sites, researchers have observed  groups of 2 to 15 octopuses engaging in behaviors like mating, poking each other with their tentacles, and kicking other octopuses out of their homes.

A paper from 2022 also reported that these gloomy octopuses “throw” things. And sometimes, it kind of looked like it was on purpose. “Throw” isn’t exactly the right word, though. It’s kind of more like directed squirting.

Still, not a very nice neighborly thing to do Ultimately, there’s not much about  these two sites that screams “city”. But the names Octopolis and Octlantis sure sound like large metropolitan areas populated by sentient cephalopods  you’d find in a scifi novel. The experts who came up with these nicknames didn’t use them in their research papers, but they’re eye-catching.

And the SciShow team is well aware of how important it is to  make a title eye-catching… Some of the media coverage  about Octopolis and Octlantis only featured the word “city” in the title, then switched to a less  suggestive term like “structure” for the rest of the article. But let’s all be honest with ourselves, how often do we only read the  headline, and then keep on scrolling? There may have also been some confusion generated by a term the researchers used in their work: ecological engineering.

To a non-specialist, it might sound  like large construction projects. If we’re sticking to the non-human sort, maybe something like a beaver dam. But it actually has a much broader definition that includes any type of environmental  modification by a living thing.

The press release announcing the  discovery of Octlantis quoted a researcher who referred to the octopuses as  “true environmental engineers”. And a few sources seem to have  extrapolated from this jargon, and claimed the octopuses also  built fences and created art. And of course, there were  those medieval walled cities that got our script editor’s hopes up… But before we get into what is inarguably  the coolest science story of all time, we’ve got to keep the lights on, so here’s an ad This SciShow video is supported by Brilliant: the personalized online learning platform.

Brilliant is crafted by an award-winning team of teachers, researchers, and professionals from MIT, Harvard,  Stanford, Caltech, Google, and more. It’s real humans teaching you  cutting-edge concepts in AI and quantum. Those experts are usually teaching  giant rooms of students all at once.

But Brilliant has packaged their knowledge into  personalized learning opportunities for you.  Brilliant starts you at the right  level based on your background, designs practice sets and reviews for you,  and helps you advance at your ideal pace.  To learn for free on Brilliant, go to brilliant.org/scishow,  scan the QR code onscreen, or click on the link in the description. They’re also giving you unlimited  daily access to everything on Brilliant with 20% off an annual Premium subscription. So putting the media frenzy aside, here’s what scientists have really  said about Octopolis and Octlantis.

The two sites do reveal the gloomy octopus is way more social than scientists once believed, and they add to a growing body of  evidence that octopuses in general are more social than we thought. That’s a valuable discovery in its own right. And now that we know these sites exist, they’ll help researchers study octopus behavior, and fill the gaps in our knowledge base about these weird and wonderful creatures.

Which leads me to one major outstanding question: Did the residents of Octopolis and Octlantis make a conscious decision  to build their communities? Scallops are part of the gloomy octopus’s diet, and waiting to snack until  you’re back inside your den is safer than out in the middle of nowhere. So it makes sense that  discarded shells would be found around a gloomy octopus’s home in large numbers.

The residents of Octopolis and Octlantis seem to be deliberately  choosing to build their dens in piles of scallop shells. But the sites themselves might  have begun as happy accidents. The experts behind the  Octlantis discovery hypothesize that the first octopus probably  built a den in the area because some shells were already present, and made for a better building  material than sediment.

This may have created a positive feedback process where the octopus brought  ever more prey back to its den and unintentionally provided  more building material as it haphazardly tossed out the trash. Another octopus may have  eventually moved into the area to take advantage of that trash, started doing its own local snacking, and so on and so forth. Suddenly, you’ve got a bunch of octopus neighbors adapting to deal with each other’s presence.

Now, this hypothesis doesn’t  mean there’s no intention behind what these octopuses are doing. Some have been observed using inedible objects like sponges to create a hatch  at the opening of their dens. They’ve also been observed cleaning their dens, using jets of water to get rid of unwanted stuff like broken shells, algae, and silt.

But if you want an octopus city, you’re gonna need more than a  bunch of individual octopuses intentionally making and managing their  own homes in the same general area. Sure, it might be a little bit too much to ask  for an octopus shopping mall or art museum. But scientists haven’t observed any  evidence of cooperative construction, or sense of sustained community.

So the main takeaway from Octopolis and Octlantis isn’t “Oh my gosh the octopuses  are building cities!,” It’s more like “Oh my gosh the octopuses aren’t   automatically a bunch of  asocial loners after all.” And they are building cool stuff These sites show that normally solitary  octopuses are highly adaptive socially, and willing to congregate if  the environment supports it. But there are still plenty  of unanswered questions. Scientists still aren’t sure  what the costs and benefits are   of living a solitary life versus a communal life.

For example, aggressive behavior in  these communal locations has costs. It uses energy and it may increase the  risk of becoming food for a predator. So scientists will have to do more research before they will understand why the  residents of Octopolis and Octlantis are choosing to stick around  for however long they do.

But in the meantime, we’re excited to see how  Octopolis and Octlantis continue to thrive And if there’s any updates,  we’ll be sure to let you know Because after all, there might be a third or a fourth Octopus City somewhere out there [ OUTRO MUSIC ]