While humans typically favour a dominant hand, new research reveals that octopuses, despite lacking a single dominant arm, show a clear preference for using their front limbs for certain activities.
Scientists meticulously analysed a series of short video clips depicting wild octopuses engaged in common behaviours such as crawling, swimming, and exploring, to observe the intricate movements of each of their eight arms. Roger Hanlon, a marine biologist and co-author from the Marine Biological Laboratory in Woods Hole, Massachusetts, expressed his astonishment: “All of the arms can do all of this stuff – that’s really amazing.”
While octopus limbs are not specialised like those of many mammals, the three species studied showed a clear preference for their four front arms, using them about 60 per cent of the time. Their back arms were more frequently employed for ‘stilting and rolling’ motions, aiding forward movement.
Mike Vecchione, a zoologist at the Smithsonian National Museum of Natural History who was not involved in the research, summarised the functional distinction: “The forward arms do most of the exploring, the rear arms are mostly for walking.”
Researchers analyzed video clips taken between 2007 and 2015 in the Atlantic Ocean and Caribbean Sea. It was the first large study to examine precise limb actions in the wild.
Unlike previous research of octopus behavior in a laboratory setting, the new work showed that octopuses did not show a preference for right or left arms in their natural environment.
Results were published Thursday in Scientific Reports.
“I’m in awe that the researchers managed to do this,” said Janet Voight, an octopus biologist at the Field Museum of Natural History in Chicago, who had no role in the study.
Octopuses are shy and elusive creatures. The species studied spend most of their time hidden in dens — meaning that filming them required patience and perseverance over many years.
Octopus limbs are complex — used for mobility and sensing the environment. Each arm contains between 100 and 200 suckers – complex sensory organs “equivalent to the human nose, lips, and tongue,” said Hanlon.
If an arm is bitten off by a predator, as often happens in the wild, octopuses have multiple backups.
“When you’ve got eight arms and they’re all capable,” Hanlon said, “there’s a lot of redundancy.”
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