In a society where right-handers are the majority, left-handers were marginalized. The right hand was even called the proper hand. Lee Jeok of the group Panic, in the 1995 release "Left-hander," likened the socially weak to left-handers and sang, "I don't mess up anything. I'm left-handed."
Human prejudice against left-handers would make an octopus laugh. An octopus has eight legs, but none are left out. Each has a different use. The front legs mainly handle exploration, and the back legs are used for movement. There is no reason to see it as strange for using any particular leg.
A team led by Roger Hanlon of the Woods Hole Oceanographic Institution in the United States said, "By observing the leg movements of octopuses in the wild, we confirmed that the legs and actions used are set according to purpose," in Scientific Reports on the 12th. Kendra Buresch of the same institution and Chelsea Bennice of Florida Atlantic University were also listed as co-corresponding authors.
◇Tracking the lives of 25 octopuses over 8 years
Octopuses swim underwater and snatch prey using eight legs. They use their legs so deftly that they can even undo the locks of a tank. We call them octopus legs, but they are essentially used like arms. In English they are also called arms. However, there has been no comprehensive study of how octopuses use their legs in real environments. Most observations were made in laboratory tanks. Hanlon said, "This time we completed the first catalog of wild octopus movements."
The team observed 25 wild individuals from three octopus species filmed in the Atlantic and the Caribbean from 2007 to 2015. Octopuses are masters of camouflage. On top of that, they spend 80% of the day hiding in shelters. The team located octopus habitats and then waited for days to film them. Bennice said, "Octopuses not only move and catch food with their legs, but also pull in rocks or seaweed to camouflage," adding, "Flexible legs are also essential for digging burrows and fending off predators or mating rivals."
The researchers analyzed 3,907 leg movements from 25 one-minute videos filmed over eight years. While watching the videos, they recorded which legs were used whenever the octopus performed one of 15 intentional behaviors, such as crawling, standing, or grasping rocks or seaweed. They also recorded combinations of 12 actions—such as curling or pushing the legs—for specific purposes, and four types of deformations—such as extending or compressing, bending, or twisting—to carry out each leg action.
The analysis found that all octopuses could deform all eight legs in four ways and that each leg could perform all actions. The base of the leg handled extending or compressing deformations, and the tip was mainly used for bending. They also confirmed that while the arms on both sides of the body were used evenly, the front four were used 64% of the time, more than the back (36%).
The front legs were mainly used for exploring the surroundings, and the back legs for movement. Because their uses differed, the actions differed as well. For example, the back legs often performed rolling and stilting actions. They rolled their legs to move along the seafloor like a conveyor belt and extended their legs to stand as if on stilts.
◇All eight are versatile, there are no left-handed octopuses
Previous studies suggested that octopuses tend to prefer the right or left legs. In 2022, a team at the University of Minnesota reported that octopuses most frequently use the second legs from the center on either side among their eight legs. Observations showed that when hunting, octopuses used the leg on the side where they saw the prey. At this time, regardless of the prey, they used the second leg from the middle first. The hunting method varied depending on the prey, but even then, the second leg led the attack. However, the scientists in this study did not observe behavior in the wild indicating octopuses are "right-handed" or "left-handed."
The team said they did not observe wild octopuses behaving as "right-handed" or "left-handed." Wild octopuses showed the ability to perform all actions and behaviors with each leg. The scientists noted that earlier research had the limitation of being conducted on octopuses raised in laboratory tanks.
Hanlon said, "The elegance of the octopus system is that there are eight legs, and all eight can perform most behaviors," adding, "This flexibility can be useful if one or two arms are lost to predators such as moray eels." It is like having many gums to make up for missing teeth.
The team said, "These results are the first to show that octopuses use specific legs for specific tasks," adding that "they can be applied to developing robotic arms modeled after octopus legs." When delivering medicine, cellphones, or water to people trapped in collapsed buildings, robotic arms that can move flexibly like an octopus according to the situation are needed.
References
Scientific Reports (2025), DOI: https://doi.org/10.1038/s41598-025-10674-y
Current Biology (2022), DOI: https://doi.org/10.1016/j.cub.2022.08.080