If you follow soccer or marine biology, you've probably heard about Paul, the octopus who correctly predicted the winners of the 2010 World Cup games by selecting tasty mussels from boxes labeled with the flags of the victorious teams. Blame statistics, experimental biases, or simple luck of the draw; you won't find me arguing that any sea creature can see into the future. But if I had to take advice from a mollusk, an octopus would be my top choice: They are surprisingly intelligent, as the NOVA scienceNOW team found out while researching a story on these underwater eggheads for the show's upcoming season.
An octopus' brain makes up a big fraction of its total body weight--relative to its body size, the octopus has the largest brain of all invertebrates--and contains hundreds of millions of neurons. Structurally, the octopus brain looks more like that of a vertebrate than that of a clam. How did the octopus evolve so much brainpower? Without protective shells, octopuses need all the help they can get to outwit their predators. Experiments in the lab and in the field have shown that they can learn, remember, and even plan ahead. They navigate mazes and learn associations between symbols and treats. Some researchers even claim that octopuses have individual personalities, though critics disagree.
Anecdotally, divers describe octopuses as clever, curious, and crafty, and aquarium workers tell tales of octopuses that escaped their enclosures and prowled through neighboring tanks as if they were so many platters at the buffet. Some of these stories may be apocryphal, but at least one botched escape left exhibits and offices Santa Monica Pier Aquarium sopping in hundreds of gallons of seawater.
Feats of octopus cunning captured on YouTube include an octopus opening a jar, apparently having mastered the "righty-tighty, lefty-loosey" rule, and an octopus snagging a coconut shell and taking shelter inside it. Octopuses can also perform virtuoso acts of camouflage, like the "Moving Rock Trick," in which an octopus impersonates a rock and moves across the seafloor at just the right pace to disguise its motion in the changing play of light and shadow beneath the waves. See for yourself:
Is that intelligence, or instinct? According to marine biologist Roger Hanlon, who studies octopuses and their cephalopod cousins, cuttlefish, at his lab at the Marine Biological Laboratory in Woods Hole, Massachusetts, camouflage can't be explained away as a simple reflex. As he told NOVA Online's Senior Editor Susan K. Lewis, "A simple reflex is a hard-wired neural system in which there's a stimulus and a response. And it's somewhat inflexible. You tend to get the same response from one stimulus all the time. The camouflage system we're talking about here is not a simple reflex because there are many potential outcomes and the animal chooses which one according to the lighted environment and the objects in that environment and its own behavioral possibilities."
Okay, so octopuses are masters of camouflage. Does that make them smart? Here things start to get a little philosophical. After all, what defines intelligence? Is it memory? Problem-solving? As Carl Zimmer writes, "If you've got a good definition, there are quite a few scientists who would love to hear it." Humans may beat out octopuses on verbal and mathematical fluency, but if humans had to sit for an octopus-designed IQ test, our species would fall flat on the camouflage section.
But back to Paul. If you're still wondering how he pulled off his impressive feat, here's something to consider. The odds of making eight correct predictions are one in 2^8, or one in 256. That's cake compared to the odds of picking a perfect March Madness bracket. And Paul wasn't the only animal oracle calling the games: According to an inventory compiled by the editors of Paul's Wikipedia page, Paul was up against a porcupine, a pygmy hippo, a tamarin, a chimp, and a menagerie of other animals that included two other octopuses. (What is it with sports and octopuses?) These critters didn't pick the winners, so their names didn't make headlines. Paul just got lucky.
How do octopuses stack up against other intelligent animals? Later this summer on NOVA's Web site, a full slate of of biologists will make the case that their favorite smart animal should be yours, too. No word yet on Paul's pick for the winner of this online poll.