Octopuses use two routines to cross openings in 30 trials

How did hole size change the strategy?

With a hole wider than the distance between the animal’s eyes, the octopus pulled its remaining arms and body through in one motion. That produced a three-step strategy: probe, shift in more arms, then pull the body across.

With a smaller hole, it moved the remaining arms first, then passed its head and mantle separately. The mantle is the bulbous main body behind an octopus’s head. That added a fourth step.

Across the 30 trials, researchers recorded 14 uses of the three-step approach with the larger hole and one with the smaller hole. They recorded 15 uses of the four-step approach, all with smaller holes.

Takeaway: A wider gap allows one final pull; a narrower gap adds a separate passage for the head and body.

Could the octopuses judge whether they would fit?

Four juvenile Maya octopuses (Octopus maya) did not attempt the smallest hole in their initial trials. Two later passed through a larger hole using the three-step method.

In a test with several holes, one juvenile tried a smaller opening first. It failed to get its arms through, then succeeded at a larger opening. These observations suggest octopuses may not judge accurately whether they will fit. The small juvenile sample makes that finding suggestive, not settled.

Takeaway: The octopus appears to act before it can reliably judge whether its body will fit.

What could this teach soft-robot designers?

Researchers say the findings could help engineers build soft robots—machines with flexible bodies—that travel through tight, unpredictable spaces such as collapsed buildings. The proposed design principle organizes simple movements under higher-level coordination instead of separately directing every limb.

Xin noted that all existing search-and-rescue and exploration robots have slender, snake-like bodies to help them move through narrow gaps. He said this limits how many sensors and manipulators—devices that detect surroundings and handle objects—engineers can pack into robot bodies, reducing adaptability during difficult search-and-rescue missions.

Takeaway: The useful robot lesson is coordinated control of simple motions, not more independent limb commands.

How strong is the evidence?

Dr. Xin and colleagues published the study on November 5, 2026, in the Journal of Experimental Biology. The paper, “Overcoming environmental constraints: octopus uses 3-step or 4-step strategies to squeeze through small holes,” lists Wenci Xin et al., volume 229, issue 21, article jeb252825, DOI 10.1242/jeb.252825.

The evidence is specific: three common octopuses supplied the 30-trial comparison, while four juvenile Maya octopuses supplied separate hole-choice observations. The significant result does not establish that every species always selects the same sequence. The robot application remains prospective, and the juvenile observations suggest rather than prove inaccurate fit judgment.

Takeaway: The study supports a repeatable squeeze-through strategy, but its small samples limit broad claims.