Common octopuses cross tight openings by dividing their movements into distinct, step-by-step physical strategies depending on the width of the gap, according to a study published on November 5, 2026, in the Journal of Experimental Biology.
An international team of researchers from Italy, Austria, and the National University of Singapore’s Advanced Robotics Centre closely observed sub-adult common octopuses (Octopus vulgaris) as they slid through differently sized holes in clear acrylic walls. Octopuses are well known for escaping tanks and finding shelter in cramped spaces, but the exact mechanical strategies they use have rarely been studied systematically. The team recorded the movements on video and broke them down into motor primitives, which are basic building blocks of movement controlled by the nervous system that can be recombined into various actions.
How Octopuses Tackle Different Hole Sizes
The motor primitives an octopus uses depend directly on the size of the gap compared to its body. When encountering a relatively large opening, the animals executed a consistent three-step sequence: probing the hole with their arms, shifting several more arms through, and then using two of the arms already on the far side to sucker onto the partition and push. That push allowed the octopus to squeeze its mantle and remaining arms through all at once.
When faced with an opening narrower than the distance between their eyes, however, the octopuses altered their approach. The animals added a fourth step, shifting their remaining arms through the gap first and pushing their mantle through separately afterward. Wenci Xin, a researcher at the National University of Singapore, noted the shift in tactics observed during the trials.
We were surprised when we found that the strategy changed,
However, after thinking about it carefully, we felt that it was understandable, as the animals were still following the same general pattern, while the new strategy simply divided the sequence in which the body was pulled through into separate stages.Wenci Xin, researcher at the National University of Singapore
The distance between an octopus’s eyes serves as a proxy for the width of its central nervous system sheath, a stiff cartilage capsule that encases the brain. Common octopuses managed to pass through holes slightly narrower than that eye-to-eye measurement by using the four-step strategy and carefully deforming their mantles with their muscles.
Contrasting Behaviors Across Cephalopod Species
Mayan octopuses (Octopus maya) showed distinct caution, while common octopuses engaged with both wide and narrow apertures. Not all cephalopods approached the experimental boxes with the same willingness.
It’s one of the most characteristic behaviors of octopuses in popular awareness, but the strategies octopuses use have not really been examined systematically.
Robyn Crook
When confronted with the narrower holes, Mayan octopuses ignored them entirely and stayed in another corner of the enclosure, only testing the smaller entry when a larger passage was offered nearby.
Designing Next-Generation Soft Robotics
Traditional robots built for search and rescue missions often rely on a snake-like design to move through narrow gaps, but robotics engineers view these biological observations as a potential solution to persistent engineering challenges. Because octopuses lack a rigid skeleton, they achieve extreme body deformations that allow them to move through tight apertures.
Understanding how octopuses organize their arms and body to adapt to environmental constraints could pave the way for flexible, squeezable machines. As Xin explained regarding the engineering implications:
This incredible capability could enable robots to overcome environmental limitations and enter spaces that are difficult to reach.
WenciXin, researcher at the National University of Singapore
While current soft robot configurations are limited, studying these squeezing strategies provides valuable design principles for machines that exploit embodied intelligence. Researchers note that there is no universal approach for these animals, emphasizing that biological constraints like cranial cartilage set physical limits on how small an opening an octopus can successfully clear.