Research showed that all eight arms of an octopus are capable of performing any task their cephalopod owner wishes, but some arms are favored for certain tasks.
A detailed analysis suggests that all eight of an octopus’s arms share a skill set, but the four front arms are favored for exploring the environment, while the four back are used for movement like walking or pushing the body.
The study findings, published on September 11 in Scientific Reports, provide a comprehensive analysis of how subtle arm movement coordinates the clever invertebrate's repertoire of behaviors.
Marine biologist Chelsea Bennice studied the behavior of how octopuses use their flexible and boneless limbs to move and investigate their environment.
During her research, colleagues analyzed video footage of three different octopus' species.
Her colleagues examined some of these behaviors in laboratory settings.
The research has confirmed that all eight arms are versatile, and they have specialized roles.
Bennice and her colleagues watched 25 videos from 2007 to 2015 of multiple species of wild octopus in Spain and the Caribbean to particularly analyze their behaviors of arm movements.
Researchers analyzed nearly 4000 octopus arm actions, which could be broken down into 12 types, and found that octopuses use their eight arms in specialized ways: elongating, shortening, bending and twisting.
According to Benice, octopuses are ultimate multimeters, and all arms are capable of all arm behaviors. They can even use multiple arm actions on a single arm and on several arms at the same time.
The research study confirms that octopuses seem to divide tasks among their arms, even though all are versatile. The front four arms are often used, and they account for about 64% percent of the general tasks.
In contrast, the rear arms are specialized for locomotion tasks such as elevating the body or conveyor-belt rolling along the seafloor.
A neuroscientist at the University of Chicago, Cassady Olson, was surprised that the study didn't expose a left-right bias in arm usage.
While the octopuses tended to use their arms in coordinated left-right pairs, they showed no true left or right handedness.
Previous research studies showed that octopuses have left-arm preferences for reaches, similar to left-hand versus right-hand dominance in humans.
These arms were tested in the lab and observed a significant difference in behavior, depending on the lab or a natural environment.
Biologists and her colleagues suggest that studying octopus' behavior could greatly benefit the development of soft robotics, which have drawn inspiration from octopuses' arms.
The detailed analysis of the team's breakdown of how small arm tweaks could create large-scale movements and designing more flexible and efficient robotic arms.
