Front arms lead exploration in wild octopuses, study finds

A new analysis of wild octopus behavior finds that while all eight limbs are capable of the same range of movements, the front four arms are used more often for exploration and manipulation and the rear four more often to support locomotion, researchers reported Sept. 11 in Scientific Reports. The team reviewed 25 video recordings made between 2007 and 2015 of three octopus species in shallow habitats in the Atlantic, the Caribbean and off Spain, cataloging roughly 4,000 individual arm actions to produce the first large-scale field accounting of how octopuses deploy their flexible limbs.

Lead author Chelsea Bennice, a marine biologist at Florida Atlantic University, and colleagues classified arm behavior into 12 action types and four fundamental deformations — bending, shortening, elongating and twisting. They found that every arm could perform every action and deformation, often simultaneously on one arm or across multiple arms. "Octopuses are ultimate multitaskers," Bennice said. The study further showed that the tips of arms were more often involved in bending actions while elongations tended to occur closer to the body.

Although the arms are largely interchangeable, the...