Octopuses (or octopi, if you prefer) are cephalopods, invertebrates that also include squid and cuttlefish. They have bulbous heads, large eyes, and eight very useful arms. “Cephalopod” is Greek for “head-foot,” which makes sense, since their limbs are attached directly to their head.

Their soft bodies mean octopuses can fit into impossibly small nooks and crannies, as long as the holes are not smaller than the only hard parts of their bodies: their beaks. If all else fails, octopuses can lose an arm to an attacker and regrow one later.

The octopus’s arms are lined with hundreds of suckers, each of which can be moved independently thanks to a complex bundle of neurons that acts as a brain, letting the animal