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Octopus arms not evenhanded

Other than an octopus, I can think of no other underwater critter clever enough to play peek-a-boo. I’ll be finning along one of the terraced walls gracing the submarine canyon off La Jolla Shores when we spot each other. I back off and sink down out of the mollusk’s view. It’s only a matter of time until my playmate leans out of the den’s opening, then inches over to see where I went and what I’m doing. I move out of sight again, and the octopus follows. I’m not the only who knows how to play the game.

Like a newborn human, an octopus has a large head in relation to its body, the better to hold the complex brain endowed within. Who knows what it thinks, but I imagine an octopus is drawn to staring at me — a giant, bubbling blob — for reasons not unlike most humans transfixed watching a train wreck (most reality programs can suffice as examples). We aquanauts are a noisy, clumsy, flailing bunch, whereas an octopus moves with a fluid grace along the seafloor, curled tentacle tips barely brushing aside sand grains, as they constantly change their outerwear to coordinate with new backgrounds appearing beneath them. From a societal stance, under water we are hoi polloi; they are blue bloods (both literally and figuratively).

Of the three octopus species found off our coast, two “bimac” octopi (Octopus bimaculatus, Octopus bimaculoides), typically top out size-wise at a foot-and-a-half from tentacle tip to opposite tentacle tip, while the diminutive red octopus (Octopus rubescens) sports a tentacle-to-tentacle stretch of about 4 inches. Bimac octopi lodge mostly in dens made from the canyon’s clay walls while half-pint red octos popularly nestle among living and inert relief on the bottom. Like much of high society, octopi are notorious jet setters. Transport by jet propulsion involves ambient water being forcefully pushed out of the body cavity via a flexible siphon. Aim the funnel in whatever angle necessary and all systems ready for takeoff. Tentacles need not apply for the job. In fact, when it comes to movement, an octopus can rightly brag, “Look ma, no arms!” A diver friend discovered this first hand on a recent night dive when a full-on octoamputee pulsed by him with nary an arm to its name.

Certainly nobody who’s anybody would be without a coat of arms, and the octopus has them in abundance. When engaged in business with prey (like crabs and some fish), having suckered arms are integral to closing the deal. They snatch and hold the victim in place until it is subdued by a toxin released from the salivary gland. Now the beaklike jaw can dispatch the carcass at leisure, exercising a sandpaper-like tongue to delicately strip off every morsel. Now that’s class!

But there’s more to those arms than just a coat and an embrace because octopus arms are bionic. To best explain, revisit the size of an octopus brain and we may agree that complex decision making must be going on around the clock up there, which includes captaining all those arms. However, with so many appendages to keep track of, in a clever nod to evolution, an octopus has eight (!) nervous systems manning the finer decisions. Thus, the octopus’s brain decides it wants an arm to move but it’s up to each of the eight independent contractors to decide which arm(s) will do so.

With so many available arm options, might there be a preference? Can an octopus be right-handed or left-handed? In some octopi studies, when blindfolded octopi were required to choose, they typically employed the arm closest to the object of interaction, meaning they had no preference. However, with eyesight restored, octopi subjects used a favorite tentacle to inspect or handle objects (despite all eight arms being equally nimble). This exciting result connects an octopus, the intellectual giants of the invertebrate world, with vertebrates, because most animals with a backbone also have a preferred eye (whether or not they have actual arms and fingers).

I know any number of avid divers who won’t pass up a lobster feast, clam bake or bowl of fish stew but won’t touch octopus. Who wants to dine on someone you know is really smart and has personality plus? Did I mention agility skills? Octopi can learn to grab certain colored balls, navigate mazes and open jars. And the brainiacs can learn to do these things just by watching their peers. Octopi, I gotta hand it to you. You are the crème de la crème of underwater society.

— Judith Lea Garfield, naturalist and underwater photographer, has authored two natural history books about the underwater park off La Jolla Cove and La Jolla Shores. Send comments to