Armed with purpose: How octopuses pick which arm to use

Octopuses may seem like they move in organized chaos, but a new study reveals there’s a method to the way these creatures coordinate their eight arms. Researchers say octopuses tend to rely on certain limbs for specific tasks, showing patterns similar to handedness in other animals.

Front vs. rear arms

“In general, we did see that for most actions the octopuses used their front arms more often than their back arms,” said Kendra Buresch, co-author of the study at the Marine Biological Laboratory, Woods Hole, in the US. The team, however, noted some exceptions.

The research, published in Scientific Reports, analyzed 25 one-minute video clips of 25 wild octopuses across three species. The footage, filmed between 2007 and 2015 at sites from Vigo, Spain to the Cayman Islands, captured behaviours like fetching objects, crawling, and even performing a “parachute attack.”

Researchers identified 15 behaviours and 12 arm actions in total, with all eight limbs capable of performing each action.When looking at overall usage, the study found octopuses relied on their front arms 61% of the time compared with 39% for the rear arms. They used their front pairs more often for reaching, raising, lowering, and curling, while the rear pairs were favored for locomotion-related actions like stilting and rolling.

Flexible coordination

“This means that octopuses can be very flexible and adaptable in many different environments and tasks,” said Buresch.



The study also explored how octopus arms deform in four ways, shortening, elongating, bending, and twisting—to perform various actions. Researchers found that multiple actions could occur at the same time, even on adjacent arms, highlighting the remarkable multitasking ability of the cephalopods.



The findings not only shed light on how octopuses manage their complex movements but may also have applications outside marine biology. As the authors write, “Such demonstrations of flexibility may help inform ethologists, sensory ecologists, neuroscientists and engineers designing soft robotic appendages.”