An octopus has no skeleton. The only hard part is the beak, and a cartilage capsule around the brain. Divers have filmed them climbing into beer bottles and soda cans for years, and the videos do well. Nobody had written down how they actually do it.

Now somebody has. A team from the National University of Singapore, the University of Naples and a Vienna aquarium put octopuses on one side of a clear acrylic partition with a single hole in it and filmed what happened from two angles at 30 frames per second. The paper is five pages long. It has a Fisher exact test in it. It is the first formal description of octopus squeezing.

The octopuses used one of two routines, and which one depended on whether the hole was wider than the distance between their eyes.

Side views show the mantle actively shrinking its own diameter on the way through. That is muscle at work, on top of the squish. Circular muscles in the mantle and transverse muscles in the arms let the animal choose its cross section.

The Mexican octopuses were a different story. Offered the small hole, they declined. They tried a little, retreated to a corner of the box and stayed there. Offered a hole of each size at once, one tried the small hole first, got two arms through, failed, and moved over to the big one, where it ran the three step routine without trouble.

Search and rescue robots have a bottleneck problem, literally. A rigid robot has to be built small enough for the narrowest gap it will ever meet, and shrinking it costs sensors, grip and power. So rescue robots trend toward snakes.

The octopus solves the problem by serializing. It sends one part through, anchors it, and uses it to pull the rest. The paper argues this looks like a higher level command that strings together simpler motor patterns, a control scheme that might let a soft robot with many floppy limbs coordinate without computing every joint at once. The senior author, Cecilia Laschi, built one of the first eight armed soft octopus robots a decade ago.

The study establishes how. It is silent on why, where and which brand. Some preliminary work exists.

Why. An octopus is a soft, edible animal in a world full of things with teeth. It wants a den with a narrow door. A beer can is a den with a narrow door that someone has helpfully left on the seafloor. Fishermen understood this long before roboticists did. Clay octopus pots on a line, the Japanese takotsubo and its Mediterranean cousins, work because the animal cannot resist a hollow. One of the references in this paper is a fisheries study of which pot designs catch which size of giant Pacific octopus.

Where. A 2022 study in Marine Pollution Bulletin gathered 261 underwater images and videos of octopuses interacting with litter and found 24 species using it, most often as shelter. Glass led at about 40 percent, plastic followed at about 25, and cans, broken bottles and old batteries all made appearances. The coconut octopus was the most frequent tenant. The ocean has a housing market, and we have been supplying the inventory.

Which beer. Here the literature is thin. The study's own sample suggests a design. The French octopuses came from La Ciotat, where pétanque was invented in 1907 and the Lumière brothers filmed a train arriving in 1895. The Mexican octopuses trace back to Sisal on the Yucatán coast. They were housed in Vienna and analyzed by engineers in Singapore and a biologist in Naples. One can per nation, hole diameter scaled to eye spacing, would settle the cultural question in an afternoon. I note only that the French animals tackled the harder opening and the Mexican animals held out for something roomier, which may say more about can design than character.

Who pays. The work was funded by a university start up grant and something called a Bridging fund, which is the right name for money that gets you through a narrow gap. The authors declare no competing interests. No brewery is listed.