How the Octopus Keeps its Eight Arms Untangled When Crawling (VIDEO)

Octopuses look gangly and odd with their many arms. Yet these creatures can gracefully capture prey and move their environment with their flexible arms. Now, scientists have made the first ever kinematic analysis of octopus arm coordination to figure out how these animals manage to stay untangled.

"Octopuses are unique locomotion strategies that are different from those found in other animals," said Binyamin Hochner, one of the researchers, in a news release. "This is most likely due to their soft molluscan body that led to the evolution of 'strange' morphology, enabling efficient locomotion control without a rigid skeleton."

Earlier studies of octopus behavior have focused on goal-directed arm movements, like reaching to a target or grabbing food and pulling it toward their mouth. This new study, though, is the first of its kind to tackle how octopuses manage to coordinate their eight long, flexible arms during locomotion.

Octopuses probably evolved from animals that were more similar to clams, with a protective outer shell and almost no movement. During evolution, octopuses lost their shell and became more maneuverable. Their "foot" also evolved into long and slender arms.

The researchers filmed octopuses and then poured over the videos frame by frame. After examining these images, the scientists found that despite its bilaterally symmetrical body, the octopus can crawl in any direction relative to its body orientation. In fact, it seems as if body orientation and crawling direction are independently controlled, and its crawling lacks any apparent rhythmical patterns in limb coordination.

The uncommon maneuverability of octopuses is derived from the radial symmetry of their arms around the body and the simple mechanism by which the arms create the crawling thrust, which is pushing by elongation.

"These two together enable a mechanism whereby the central controller chooses in a moment-to-moment fashion which arms to recruit for pushing the body in an instantaneous fashion," write the researchers.

The findings are published in the journal Current Biology.

Want to learn more? Check out the video below, courtesy of YouTube.

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