Ozy the octopus once unscrewed the lid of a glass jar in 54 seconds. It's likely the record for octopus jar-opening, a common trick among the mollusks. Octopuses learn the trick so easily, in fact, that about 10 years ago, scientists at the Seattle Aquarium gave an octopus a herring-filled medication bottle to see what it would do with the childproof cap – the kind you need to push down and turn simultaneously. It opened it in 55 minutes. With practice, that was down to five.
Just how smart are these creatures?
Simple answer: pretty smart. They can figure out how to open a childproof cap without instructions.
Complicated answer: Octopuses evolved under such dramatically different conditions from humans that grasping their level of intelligence would require a rethinking of the very meaning of "intelligence" as we understand it.
Scientists believe human minds evolved in large part to survive and thrive in complex social constructs, writes Sy Montgomery in this excellent Orion magazine article. Octopus minds, one theory states, evolved to survive in a complex deep-sea environment without shells.
Octopuses are cephalopods, a category of mollusk that also includes cuttlefish and squid. Octopus brains are tiny by human standards, but they're proportionally the largest among invertebrates, writes Montgomery. They're also the most like human brains: In most mollusks, neurons are distributed throughout the body in something of a web. In octopuses, neurons condense to form a central brain, complete with separate lobes that store information.
Although octopuses have far fewer neurons than humans, what they lack in neurons they make up for in brains: They have nine. Most of their neurons are in their eight arms, and if one is cut off (not to worry, it regrows), the severed limb continues to act with purpose. Scientists have witnessed one grabbing food as it drifts away, directing the catch to where the octopus's mouth would be if the arm were still attached to the body.
As scientists dig deeper, they're discovering some evidence of intelligence as humans understand it. Octopuses' problem-solving abilities are beyond question, what with the jar opening (from the inside, when necessary), a reputation as escape artists and a talent for taking apart whatever they find in their tanks, including Mr. Potato Head. Researcher Jennifer Mather with the Seattle Aquarium sees the possibility of planning and foresight: She watched an octopus come out of its den, select three rocks from the sea floor and set them aside in a group, carry them back to the den and build a rock wall in front of the entrance. The octopus then went to sleep for the night behind its barrier.
In captivity, octopuses appear to play. There's some evidence of personalities. They not only use tools but do so selectively and adaptively. When Mather and colleagues tossed mollusks and clams with varying shell strengths in the octopus tank, the octopuses cracked the weakest shells, pried open the middle-range shells and drilled into the strongest (part of the octopus "beak" acts like a drill). When the middle-range shells were wired shut, the octopuses first tried prying, as before. When that failed, they started drilling.
Octopus "thinking" is still something of a mystery to science, and a lot of the evidence pointing to some kind of human-like intelligence is anecdotal. But if octopus brains indeed evolved for survival without their shells, the creatures are brilliant. A massive octopus can squeeze through a crack. The shape-shifting is even more jaw-dropping. Using layers of pigmented cells beneath the skin and its utterly malleable form, an octopus can change color, pattern, shape, and texture to mimic a sea snake, poisonous lionfish and flatfish, stingray, jellyfish, algae, coral — pretty much anything that will throw off a predator.
The "moving rock" might take the cake, though. An octopus perfectly mimics a rock on the sea floor. It then creeps to safety — undetectably, because it's moving at the exact speed that light is moving through the water. Predators swim right by.