When common octopuses encounter a gap wider than the distance between their eyes, they slip through in a consistent three-step sequence of probing with their limbs, shifting arms through, and pushing off the surrounding partition with two suckered arms to yank their head and mantle through at once, according to a study published November 5, 2026, in the Journal of Experimental Biology.
Measuring Cranial Capsules to Test Tight Spaces
Researchers examined three sub-adult common octopuses (Octopus vulgaris) and four Mayan octopuses (O. maya) by constructing clear acrylic aquarium boxes linked by holes of varying sizes. Before testing the animals, the science team measured the distance between each octopus’s eyes to approximate the width of the stiff cartilage sheath encasing its central nervous system. This cranial capsule, along with the chitinous beak, represents the only rigid part of an octopus’s body that does not easily compress.
The trials revealed that common octopuses and Mayan octopuses approach tight spaces differently. While common octopuses actively tested narrow portals, Mayan octopuses displayed more cautious behavior. When confronted with a hole narrower than the distance between their eyes, Mayan octopuses ignored the opening entirely and only engaged when offered a larger adjacent passage, Popular Science reported. Michael Kuba, a biologist at the University of Naples Federico II in Italy who helped run the work, notes that sneaking through small spaces is not merely a party trick for these cephalopods, as the animals utilize the skill to find hidden food and avoid predators. Not many scientists have studied how these animals squirm through small openings, according to Robyn Crook, an evolutionary biologist at San Francisco State University who was not involved in the research. In earlier work, Kuba and colleagues filmed octopuses reaching one arm through a hole, with more arms following with shorter reaches until the opening was almost completely filled, before the arm stretched out on the far side.
Shifting Strategies for Tighter Apertures
When common octopuses faced gaps narrower than their cranial cartilage width, they switched from a three-step routine to a four-step strategy.
We were surprised when we found that the strategy changed
Wenci Xin, mechanical engineering researcher at the National University of Singapore
The researchers filmed 33 escape attempts across the trials at a public aquarium in Vienna, recording 30 successful runs after three attempts resulted in apparatus damage. The animals consistently favored their front limbs, utilizing the second left arm first in 47 percent of the trials, followed by the first left arm in 28 percent of the attempts, according to Earth.
Designing Soft Robots for Search and Rescue
The findings offer concrete mechanical blueprints for engineers developing soft-bodied robotics. Current search-and-rescue robots designed to navigate collapsed buildings or confined spaces typically rely on a long, narrow, snake-like architecture. Wenci Xin, a postdoctoral associate at the Singapore-MIT Alliance for Research and Technology (SMART) Centre and a mechanical engineering researcher at the National University of Singapore, noted that observing how cephalopods coordinate specific postures and body parts provides valuable insights for biomimetic engineering, as reported by IFLScience. Working with animals proved challenging for the engineering team; as Dr Xin explained to IFLScience, being an engineer accustomed to machines following direct commands makes dealing with unpredictable living subjects uniquely difficult.
If we could develop a squeezable, octopus-inspired robot, such a design could accommodate a larger range of functional components while retaining access to confined spaces
Wenci Xin, Postdoctoral Associate at the Singapore-MIT Alliance for Research and Technology (SMART) Centre
The international research collaboration combined cephalopod biology expertise from institutions in Italy and Austria with robotics research from the Advanced Robotics Centre at the National University of Singapore, publishing their findings in the Journal of Experimental Biology.