This octopus grew a ninth arm—which soon developed a mind of its own
From Science Magazine. When an octopus injures an arm, the appendage can split in two, giving the cephalopod an extra limb. But it’s long been unclear just how functional this ninth arm is, or how octopuses gradually accustom themselves to reusing the arm. In 2025, the first long-term observation of one of the animals in…


