Octopus intelligence: Here are 13 of the most frighteningly smart things they can do.

Prepare to meet your match, humans: The otherworldly, intelligent octopus.

Octopus. Photo by Jens Petersen/Wikimedia Commons.

We've been poking at these wily mini-sea monsters with sticks, shutting them inside aquarium tanks, and grilling them with slices of lemon for thousands of years. But did we ever stop to consider how clever the octopus truly is?

Turns out, this creature's brain not only makes it the world's most intelligent invertebrate but, according to some measures, as smart as a golden retriever.

(OK, OK, yes. I hear your screaming, scientists. Comparing octopus intelligence to mammal intelligence is a dubious proposition, but the point is, they're really freaking smart.)

Combine that with their eight tentacles, each of which has a mind of its own (seriously), and you've got a force to be reckoned with.

Still not convinced? Here are 13 startlingly brilliant things that octopuses appear to be able to do that no creature so goopy and gangly should be able to do.

1. Octopuses* can bust out of their aquarium tanks and find their way back to the ocean.

By now, you've probably heard the story of Inky, the New Zealand octopus that got bored sitting in an aquarium being gawked at by cranky, field-tripping children and escaped via a drainage tube that led back to the sea. It's hard not to shake the feeling that he's seen too much and we're doomed.

*Right about now, you're probably flexing your fingers, gleefully preparing to type "Um, don't you mean octopi?" into that tantalizingly eager comment field, experiencing the delicious rush stoked by the opportunity to telling a stranger on the Internet just how wrong he really is. However, while "more than one octopus = octopi" is indeed every fifth graders favorite fun fact — and our fifth graders deserve all the support and encouragement in the world — "octopuses" is also correct, and that's the one we like best. Check it out.

2. They can slip their entire body through a hole the size of a medium-length hardcover novel.

GIF via Zena Cardman/YouTube.

Oh, you think you've got one over on that "helpless" octopus sliding around the deck of your boat. Uh uh, my friend. Once he finds an opening that roughly equals the lengthwise dimensions of a book that's slightly shorter than "Freedom" but a little bit longer than "The Road," that guy is gone like the wind.

3. Octopuses can open jars. From the inside.

No one keeps Baby in a jar.

GIF via Beata Svengt/YouTube.

4. Octopuses can open jars. From the outside.

However, Baby will get down with a jar to consume the poor unsuspecting creature hiding inside for dear life while holding the lid victoriously aloft like a trophy.

GIF via fishgurl35/YouTube.

5. Octopuses have also been known to defend themselves with rocks.

Come at me, bro. Photo by Sylkie Rohrlach/Flickr.

Cephalopod intelligence researcher Jennifer Mather reports observing octopuses building stone defensive structures outside their dens to protect themselves while they sleep.

Likely, these will be the battlements humans will be storming if the forces of humanity aren't too devastated by the initial octo-assault to counterattack.

6. They can take apart the plumbing of their own tanks, causing sweet, soggy mayhem.

Artists rendering. GIF via Nickelodeon/YouTube.

It happened in Santa Monica, where an octopus commandeered a water recycling valve and proceeded to wreak havoc on the aquarium's new eco-sensitive floor.

An innocent mistake? Or the start of a complex financial scheme that involves forcing the world's aquariums to accrue massive debt on floor maintenance, and hm ... just look who's waiting in the wings with a line of sweet, easy credit:

Let's make a deal, human. Photo by Eistreter/Wikimedia Commons.

A few strings attached, of course.

7. Octopuses have been seen jumping up on land to ambush unsuspecting prey.

GIF via CNN/YouTube.

Sure, he's taking a risk. He definitely can't survive up there for long. But killing is just that important to him.

8. They've also been known to turn out the lights for their own petty amusement.

Hellllloooo? Photo by Eric March/Upworthy.

At least, that's what an octopus in Germany did, just to mess with aquarium employees. Once he figured out that shooting water at an overhead spotlight would cause the simple humans below to scramble around like chickens with their heads cut off, that's exactly what he did. Again and again and again.

Yes, for these whimsically sadistic creatures, life is a laugh track, and we are the punchline.

9. Octopuses have been spotted making tools out of coconuts and shells.

Image by Nick Hobgood/Wikimedia Commons.

We've only known they could do this for about five years. And we've been readying our machete and flexi-straw-based defenses ever since.

10. They can also mimic other deadly sea creatures to scare the bejeezus out of potential predators.

A seemingly ordinary poisonous water snake? An octopus? You WILL NEVER KNOW. (OK, this actually is snake. But now you're on your toes! And you should be!) Photo by Jon Hanson/Flickr.

At least some species of octopus can camouflage themselves so well they look like poisonous fish or snakes to their enemies.

Why they would want to do this — considering that they are already terrifying octopuses — is unclear.

11. Octopuses have also been known to kill sharks.

Here, the octopus does so with a sneaky pre-emptive strike.

GIF via National Geographic/YouTube.

Aquarium employees put a shark and an octopus in the same tank. This did not sit well with the octopus.

Octopus solution: Strangle the shark in cold blood. Obviously.

12. They've also been known to escape their tanks to eat a fish in an adjacent tank and then return to their own tanks before anyone notices.

No walls can contain me! Image by WingedWolfPoison/Wikimedia Commons.

A number of these stories have been reported over the years (dating all the way back to the 1875), and some claim they're apocryphal, but this particular one appears to have actually happened in Boston in the 1980s.

According to aquarium employees, a giant Pacific octopus was caught leaving its enclosure and ambling a few feet to the next tank over, enticed by a number of rare, expensive fish that had been brought in.

For a $14 appetizer, that's really next level.

13. Octopuses have accidentally documented themselves stealing our video cameras to cover up evidence of their crimes.

GIF via Victor's Videos/YouTube.

We have the footage. We know what they're up to. And yet, we're probably powerless to prevent it.

Bear in mind: These facts are just what we actually know about octopus intelligence. There is clearly still a lot to learn and understand about them.

All in all, they're pretty fascinating creatures, and sharing the Earth with them is pretty awesome.