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BOOK EXCERPT

Shape-Shifting Cephalopods

Drew Harvell

For more than two decades, ecologist and evolutionary biologist Drew Harvell has been the curator of Cornell University’s collection of 569 glass models of marine invertebrates, crafted in the 19th century by Leopold and Rudolf Blaschka. These astonishingly detailed pieces were originally used for classroom instruction. In 2011 marine videographer David Brown approached Harvell with the idea of locating in the wild each species represented in Cornell’s collection. During the global travels that followed, the pair discovered much about how changing marine conditions have affected the living counterparts of the Blaschka models. And for Harvell, these undersea encounters brought new dimension to the collection she has restored and championed.

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For all of the cephalopods’ remarkable traits, there is one that researchers are still trying to wrap their heads around: the ability to quickly shape-shift, or transform, from a rock to a piece of drifting algae. For example, cuttlefish are called chameleons of the sea because of the split-second color and shape shifts. Watching two cuttlefish together is like watching a conversation in color. In competing males, low mutters of muted shades change quickly to emphatic shouts of sharp, dark colors. Passionate love calls between meeting pairs are shared in vibrating colors that wash along the body. It boggles the mind to see two conversations occurring at the same time on a single animal; I once saw a male cuttlefish crooning a colorful love call to a female along the side of his body facing her while simultaneously edging out a male with the sharp, jagged territorial display on the other half of his body. The rather serious octopus scholar Roger Hanlon made his audience laugh with the joke that this type of two-part conversation is evidence that males have been two-faced from earliest evolutionary time.

The uncanny camouflage of octopus and cuttlefish requires large but precise color and body surface texture changes. Sacs of yellow, red, brown, and black pigment called chromatophores are opened and closed by muscles that orchestrate instant, coordinated color changes. Muscular contractions change skin texture from as smooth as glass to as craggy as a drift of algae. The degree of shape and color matching of underwater objects is a conjurer’s trick. It includes all the color and shape changes and behavior that mimic exactly the object being imitated—for example, mimicking a coconut shell bouncing along the ocean bottom or a piece of algae floating by. Once, on a dive to a very scroungy reef near a fish farm in the Philippines, I saw a foot-tall piece of floating algae start to swim purposefully away and realized it was actually an octopus. Once we started to watch her, she gave this “Uh oh, busted!” kind of shrug and went through a frantic series of shape and color matches to everything around her, from rocks to algae to coral heads. How strange to realize that in this riot of color change, octopus are themselves color blind.

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JUST AHEAD I SEE a large lighted glow from dive lights. There it is—the ornate octopus! The octopus sits stolidly in the light of the camera, not too bothered by the attention. It’s an unusual shade of orange with bright white spots and dashes along all its arms. It’s beautiful. I tentatively reach out a finger to touch a tentacle. It touches calmly back with its suctioned tentacles, then scuttles in the other direction, but I easily herd it back between my cupped hands. All the while it watches me with large amber eyes.

This time as I herd her, I’m braver and ready for the jetting trick. As she lifts off, I catch her gently in midair, almost like some large bird, except one with eight sticky tentacles. Holding her at eye level, I look into her eerie, knowing eyes. Then a tentacle slaps onto the front of my mask, and the octopus crawls up my arm. I feel like the octopus whisperer.

This is the moment I fall in love again with the unexpected, otherworldly, and profoundly beautiful biodiversity in our oceans—this animal is so exquisite in form, so interesting, and so unlike anything else on the planet, it’s heartbreaking to know that we are systemically, and often wantonly, destroying it and its world. I relish all my invertebrate field experiences, but this one stands apart. Luckily for me, videographer David Brown and I are going to dive again the next day. The strategy for our next dive is to be up before sunrise and in the water with the rising Sun, hoping the day octopus will be venturing out.

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We arrive before the Sun at our shore site on the wave-crashed Kona-Kohala coastline. It is always a bit tough to clamber over the sharp lava rock laden with heavy tanks and dive weights, but we make it underwater as the Sun rises. The morning glow illuminates a crystalline seascape filled with bright yellow tang fish, autumn-colored coral heads, and large lurking trumpet fish.

Looking for an octopus that doesn’t want to be seen can be a tough prospect, so I am prepared for a long hunt. It seems so improbable as to be fated, because within minutes of entering the water, I spot a dark brown smudge on the edge of a coral. The smudge ripples, transforming what at first looked like rock face into a foot-and-a-half-tall camouflaged octopus. I can’t believe that we are so lucky as to have found the exact animal we wanted right away. As we approach, the cat-sized octopus withdraws partly into its den. But it is bold and actively watches us, soon easing back up along the rock, tentacle by tentacle.

It’s clearly curious, elevating periscoped eyes as high as possible to watch us from beside the den. As I move away, it eases out further, craning its eyes to watch. It’s quite comical. After a while, it settles and stays put, body flickering through a kaleidoscopic color change from beige to deep brown to a mottled paisley.

I try to entice it out by running my fingers back and forth and then tapping on a rock, like playing with a cat. No dice. It eases up a little further from its burrow and cocks an eye, but no tentacle reaches out to sample my game. Meanwhile, trumpet fish, attracted by David’s camera lights, have gathered to watch the drama as David tries to film, laughing as he steadies the camera.

I move away a bit to see what happens. No sooner do we ease back 10 feet or so than the octopus, far larger than I had realized, lifts off its rock stronghold and jets across the reef. What a spectacle—a big octopus, in full swim with long tentacles trailing three feet behind the massive webbed body. In stealthy pursuit, we watch as it settles again to the reef, with a fast-paced race through its repertoire of colors, this time from brown to maroon to beige to vibrantly striped and back to brown.

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This is my chance. As the octopus lifts off again, I reach to catch it in midflight. After the easy time I had with the delicate ornate octopus the night before, I am unprepared for how strong this big one is, and there briefly ensues a bout of extremely uneven interspecies grappling. Through a rain of tentacled suckers, I try with two arms to hold eight. As if that wasn’t enough, we are both suddenly engulfed in a huge, blinding cloud of dark brown smoky ink. I can say from firsthand experience that inking is the strategy to confuse a would-be predator. This marine Houdini eluded me in seconds and was once again across the reef and into the safety of another den.

David continued trying to film this, but as I looked over, we both flooded our masks laughing. He had just filmed a ridiculous spectacle of me rolling around on the sand with this octopus, ending with us both enveloped in ink and the octopus calmly jetting off. Despite the quick end to our dive, we left so pleased to have found both of these octopus so easily. Despite strong hunting pressures in the Hawaiian Islands, they seem to be doing well.

From A Sea of Glass: Searching for the Blaschkas’ Fragile Legacy in an Ocean at Risk, by Drew Harvell. Copyright © 2016 by University of California Press. Used by permission of the publisher.

Drew Harvell is a professor of ecology and evolutionary biology at Cornell University and curator of the Blaschka Marine Invertebrate Collection. Her research on the sustainability of marine ecosystems has taken her from the reefs of Mexico, Indonesia, and Hawaii to the cold waters of the Pacific Northwest. She has published more than 120 articles in journals such as Science, Nature, and Ecology; is coeditor of The Ecology and Evolution of Inducible Defenses; and is a lead author of the oceans chapter in the 2014 National Climate Assessment.


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