Intelligent arms

With the ability to twist in every direction and suckers that can grip and release individually, octopus arms are much too complicated to be controlled from a central brain. Instead they operate semi-autonomously. An octopus issues instructions and trusts that they will be carried out, and occasionally it has a look to make sure. This means that an octopus doesn’t have a very good idea of where its arms actually are at any moment and can’t work out the shape of something by feeling it, like we can. Octopuses can taste through their suckers and can detach an arm and regenerate a new one if they need to give you the slip. One species, the paper nautilus, uses an arm to deliver sperm. It detaches and swims across to the female all by itself.