Life The third right arm of male octopuses has a specialised role in mating, and the creatures take extra care to avoid damaging it or losing it to a predator Facebook / Meta Twitter / X icon Linkedin Reddit Email A male webfoot octopus ( Amphioctopus fangsiao ) with its hectocotylus curled up (upper left) Keijiro Haruki For a male octopus, there is one appendage it cannot afford to lose. This is its third right arm, which has a specialised role in sex. Therefore, they take extra care to protect it. A new study led by Keijiro Haruki at Nagasaki University, Japan, has revealed the lengths octopuses will go to ensure their most precious arm stays safe from getting damaged or bitten off by a predator. Haruki was inspired to conduct the research after softly touching each of a male octopus’s arms with his finger. “He would strongly resist when I touched one particular arm and pull it back towards his body,” says Haruki.…