Map of current land and ice separating the Weddell and Ross seas, courtesy of Wikimedia Commons/Wutsje/CIA

Octopuses have made themselves at home in most of the world’s oceans—from the warmest of tropical seas to the deep, dark reaches around hydrothermal vents. Antarctic species, such as Turquet’s octopuses (Pareledone turqueti), even live slow, quiet lives near the South Pole. But these retiring creatures offer a rare opportunity to help understand how this extreme part of the Earth has changed in recent geologic times—and what climate change might bring there in the near future.

Researchers can compare genetic patterns of current animal populations to look back in evolutionary time to estimate when populations of animals might have split off. These fissures are often forced by changing climatic or geographical features, such as giant sheets of ice that come and go with different glacial patterns. The West Antarctic Ice Sheet and some low Antarctic land currently separates the Weddell Sea from the Ross Sea in the Southern Ocean.

Research has suggested that this ice shelf has collapsed a number of times in the past—likely during the Pleistocene interglacial periods, most likely starting some 1.25 million years ago. This melting, along with rising sea levels, would have opened up a seawater thruway between the Weddell and Ross seas for marine life. So scientists have been turning their attention to contemporary species in the two seas to see if they could track their evolutionary history back to a time when these disparate populations might have been connected.

Turquet's octopus preserved specimens from 1914 courtesy if Wikimedia Commons/Charcot/Joubin

“We wanted to investigate whether there was any genetic information that could tell us what the past environment could have been like,” Louise Allcock, of the National University of Ireland Galway’s zoology department, said in a prepared statement. And for that, she and her colleagues turned to the benthic Turquet’s octopus, which lives as deep as 1,000 meters on the seafloor in the Southern Ocean.

These particular polar octopods, which grow to only about 15 centimeters in length, are found all around the continent, but they don’t like to stray too far from home, remaining on the ocean floor most of the time and swimming only in short bursts to escape predators.

“This octopus species, with its large populations around the region and limited movements, was an ideal species to use,” Allcock said.

And unlike most octopus species, Turquet’s octopus lays relatively few, large eggs (between 22 and 60, each about 20 millimeters long). So when they hatch, instead of floating up into the water column like plankton, as most species of octopus larvae do, these more massive little ‘uns start living on the sea floor like their parents. This lifestyle prevents them from dispersing in great numbers with the currents. Plus, both the Weddell and Ross seas have their own circular currents (gyres) that tend to keep any organisms in the area. These factors mean that population pockets of this octopus likely do not mix with others and thus each population would be expected to have developed different genetic signatures across generations if they had been separated for a long period of evolutionary time.

The research team used data collected by the Census of Antarctic Marine Life from more than 450 individual Turquet’s octopuses from around the continent’s edges. Through that they were able “to examine genetic data on a scale that had not been done before in this area of the world,” Phill Watts, of University of Liverpool’s Institute of Integrative Biology and co-author of the study, said in a prepared statement. The new findings were published recently online in Molecular Ecology.

And when they did look into the genetic code they found something surprising. “We expected to find a marked difference between Turquet’s octopuses living in different regions of the ocean,” Watts said. But they found that the genetics of the two populations were actually very similar, “suggesting that at some point in their past these populations would have been in contact with each other, perhaps at a time when the oceans were connected and not separated by the West Antarctic Ice Sheet,” he said.

The team found genetic evidence of a large population growth about 1902 near South Georgia and around 1829 at Shag Rocks. And the DNA data also suggests that These tough little critters seem to have been able to ride out even the cold glacial maximum periods in these and other areas.

The new findings shore up “with climate models indicating repeated periods in history when the climate was warmer, which would have released water from the ice and increased the sea levels, allowing dispersal of creatures between the Ross and Weddell seas,” Watts said.

Not only does this new genetic picture help support climate patterns of the past, but “it also provides further evidence that scientists should continue to raise awareness about the impact of climate change on Antarctica today,” Allcock said. So these octopuses might not be psychic, but they might help us place bets on whether they’re likely to be reunited once again in the future near.

Illustration courtesy of Ivan Phillipsen

Courtesy of Basic Books

Octopuses possess camouflage abilities that put some of our military’s best high-tech efforts to shame. And their flexible, intelligent arms are the envy of roboticists and artificial intelligence engineers worldwide.

But these animals, which have evolved over hundreds of millions of years, can teach us even more about security in the 21st century than camo and communications, Rafe Sagarin argues in his new book Learning from the Octopus: How secrets from nature can help us fight terrorist attacks, natural disasters and disease (Basic Books, April 2012).

Sagarin suggests we take cues from octopuses and other organisms in the natural world to make our responses to all kinds of threats—from sophisticated terrorist cells to emerging infections—more robust and adaptable.

Sagarin is a research scientist at the University of Arizona’s Institute of the Environment. Trained as a marine ecologist, he has spent a lot of time gazing into the ocean, thinking about the marvels of animal adaptability in the face of danger, which is what got him thinking about these impressive cephalopods.

Octopuses lack a protective shell—as well as any internal skeleton. So they have developed a myriad of strategies for staying safe (which leads us to the first three lessons for improved security: redundancy, redundancy, redundancy).

When an octopus is out and about, “millions of cells on the surface of its skin are all sensing and responding to the world around, instantly changing shape and color to perfectly match their immediate surroundings,” he writes in his book.

Once, after staring at a tide pool in Baja California for a long time, I thought I spied an octopus, but the small waves cresting the tide pool walls riffled the surface too much to be sure. My eyes failing me, I reached my hand in to engage my tactile senses, and instantly a dark cloud of smoky ink filled the pool. By the time it cleared, I had confirmed my identification, but the beast was long gone.

It’s hard to imagine humans ever being quite this stealthy (read more about this research in Sagarin’s book). But what I really wanted to know was how he made this cool conceptual leap from thinking about slippery invertebrates to beefed up national security, anyway. I called him up just before he left for his book tour to find out.

[An edited transcript of the interview follows.]

What first got you thinking about the octopus as a good animal for thinking about security issues?
I first was thinking about nature in general as a good model because of the way all natural organisms have to deal with uncertainty and how they have to adapt to an uncertain world. I started to think about organisms as metaphors and octopuses kept coming to the top. They express their adaptability in so many different ways.

You already hinted at an answer to my next question—do you think of the octopus as an example to follow or more as a metaphor?
It’s both, really. In some cases, it’s just a metaphor because there are translational issues—because we have certain ethical norms and different political and economic realities where we can’t do exactly what nature does.

In some cases it does work well to decentralize observing [as the octopus does via its skin cells]. And those are some of the things it works to adopt almost verbatim from nature.

Why not squid or cuttlefish?
I’ve always had a fondness for octopuses. Even though squid and cuttlefish have some really remarkable abilities, octopuses really have it all. They’re probably more intelligent than squid or cuttlefish; they have the camouflage ability; they also think about things and plan out what they are going to do.

Another thing they do is they show is that a lot of the boundaries we’ve put up in the past between humans and other organisms in the living world have already been crossed. Octopuses already do things we were often told that non-humans just don’t do [such as use tools]. They’re a really good exemplar of this general point that humans and the rest of the animal world are different—but not that different.

You also mention in your book the ability of octopuses to use tools and plan for the future, which I think we consider ourselves pretty good at, as a species—is there still something more we can learn from that?
I think it’s that we have to not be so prejudiced against taking advice from the rest of the natural world. If we can get over that thinking that there’s a boundary [between us and it], then we can open our minds to the ideas that we can learn from these other organisms.

So you’re trained as a marine ecologist, but you also seem to dabble in policy and security issues. These seem like pretty different fields—how did you get into those areas?
I’ve always been interested in the interface between science and policy. I worked for Congresswoman Hilda Solis for a while, and that’s really where this particular project started. I was working in D.C. after 9/11, and I remember noticing all this extra security but not being very impressed by it, by its adaptability and ability to meet a changing threat.

If we could borrow one thing—one lesson—from the octopus what do you think it should be?
I think it’s this combination of having a lot of ways to see change in the world, combined with a lot of ways to respond to that change: Having redundancy in the way you see the world, as the skin cells of the octopus demonstrate, but then having a lot of ways to respond to that change.

If you can always try to make that combination in what you’re doing, you’re going to be a lot more successful, rather than relying on a small number of responders and a small number of “best practices.”

What lesson from the octopus do you think will be most difficult for us to integrate into our current way of thinking?
In talking to people it seems the most difficult is a fear of getting started, a feeling that: “We’re already stuck in these huge bureaucracies that are not at all like the decentralized concepts you’re talking about.” But what you find is that when people in these organizations start to do these things on their own, things start to fall into place. My big thing is: “Just get started.” Start by having people respond to unusual challenges.

Okay, so we both seem to agree that the octopus is awesome. But if you had to look to another animal for bio-inspiration—to help us learn how to respond to challenges better—what would you pick?
That’s a hard one. It really depends on the lesson. There are exemplary species for many lessons. Communicating with an enemy is an important one. It’s really interesting to see that ground squirrels send very direct messages to their predators that can hear—very loud noises. But for snakes that can’t hear, a squirrel puffs up its tail. But if it’s a rattlesnake that can sense heat, a squirrel will heat up its tail. That shows that the squirrel has learned to communicate with its predators in its predators’ own languages, rather than send out vague messages—like we do with airport security messages. Saying that we’re at “threat level orange” communicates to our enemies that we really don’t know anything.

Anything else?
Organisms in nature have survived and thrived for three and a half billion years, and they’ve done it without any kind of planning or predicting, or anything that we spend so much of our time doing. They have a very efficient process for dealing with unknown threats.

Illustration courtesy of Ivan Phillipsen

Image courtesy of Shelby Temple

Octopuses are purportedly  colorblind, but they can discern one thing that we can’t: polarized light. This extra visual realm might give them a leg (er, arm) up on some of the competition.

And a team of researchers has created a new way to test just how sensitive cephalopods are to this type of light. Their results were published online Monday in Current Biology.

“We now know that polarization is tuned much more finely than we thought it was,” says Shelby Temple, of the Ecology of Vision Laboratory at the University of Bristol in the U.K., who led the study.

But testing polarized light is tricky, especially since we humans aren’t tuned to see it. As Temple and his co-authors wrote in their paper: “For animals that can see it, the polarization of light adds another dimension to vision, analogous to adding color to a black and white image.” Polarized light is different from what we see in that it comes from a single angle, and animals that can detect it seem to see it in different resolutions based on changes in its angle. (The closest we can get to using it is putting on a pair of polarized lenses to cut down on glare.)

Polarized light perception in the best-tuned animals was assumed to be limited to differences of about 10 to 20 degrees. But in the group’s new experiments, the mourning cuttlefish (Sepia plangon) responded to just 1.05-degrees change of polarized light orientation.

For the experiments, the team used computer screens that had had the polarizing light filter removed (without these front filters on our liquid crystal displays—LCDs—our monitors would project polarized light images that we wouldn’t be able to see).

These modified displays played digital movie versions of “looming stimuli” such as an expanding circle, which would suggest a potential predator approaching. But instead of a color or intensity-based image, the one they created was based on changing polarized light orientation only.

Image courtesy of Shelby Temple

Octopus don’t yet seem to be quite as sensitive as cuttlefish to the fine gradients in polarized light, responding only after about 10 degrees shift. But, says Temple, “it may be the way that we’re testing.” As he points out, cuttlefish’s knee-jerk response to an approaching predator is a quick change of color, which the researchers could use as an indication that they had seen even fine shifts in the polarized light angle.

“Cuttlefish, they wear their emotions on their sleeve, quite literally,” Temple says. “They’re showing everything that they’re doing as a neural response.” In fact, the cuttlefish responded so well, that he and his colleagues thought they were doing something wrong. They were afraid that in the digital renderings they might have accidentally included a non-polarized light clue, such as brightness or intensity. But they went back and checked and found that it was, indeed, just the slight change in polarized light that was frightening the animals.

With octopus, “there’s no comparison,” he says. But, he concedes that it is possible that the octopuses might have seen finer resolutions of polarized light shift but just didn’t have the same simple, speedy reaction as the cuttlefish.

And says Temple, “it could be that some species could do it better than others.”  So far, he has found that the blue ringed octopus looks to me more sensitive than the day octopus. He has plans to test different species of octopus soon.

Researchers are still working to get to the bottom of cephalopod vision, which is turning out to be highly complex. And this new work supports the idea that such sensitivity to polarized light emerged precisely because these animals don’t see color well—if at all.

Image courtesy of Shelby Temple

And if octopuses, cuttlefish and squid—and some of their predators and prey—can see polarized light so keenly, are they also using it, as they use color and luminosity, to actively create camouflage?

Other researchers are working on that very question. And Temple and his colleagues have observed that, at least in some cuttlefish, they can create a polarized light-based pattern on their skin. This play in light might “be used as part of a covert communication channel, invisible to animals lacking polarized vision,” they wrote.

But the patterns remain tricky for us to pick up on. For that, Temple and his colleagues have developed a way for us to get a peak into the invisible world of polarized light and dark by modifying a digital single-reflex lens (SLR) camera and creating a computer program to feed false-color into varying degrees of polarized light. These mysterious rainbow-colored ecosystem images make it clear that, “We’re not done with the story yet, for sure,” Temple says.

Illustration courtesy of Ivan Phillipsen

Octopus vulgaris. Courtesy of Wikimedia Commons/Beckmannjan

Without genetic change we’d be nowhere—well perhaps just unicellular blobs kicking around in ponds. Alterations in DNA, such as point mutations, duplications, rearrangements and insertions from microbial neighbors, have helped humans and our deep-time ancestors climb out of the swamps and, in our case at least, start swimming in backyard pools.

But these basic tools of evolution don’t entirely explain how we and other organisms have evolved to be so complex. Recent research has shown that a process called RNA editing, which tweaks how certain enzymes are made without requiring alterations in basic genetic blueprints, has allowed living organisms to regulate important functions, such as nervous system function and development.

Now, octopuses have provided the first evidence that this sort of micro-tinkering can happen in response to external environmental cues rather than just internal developmental ones. In a paper published online Thursday in Science Express, two researchers explain how RNA editing has allowed octopuses to adapt to the warm waters of Puerto Rico down to the icy depths of the Southern Ocean near Antarctica.

“RNA editing gives an organism options,” Joshua Rosenthal, of the University of Puerto Rico Medical Sciences Campus’s Institute of Neurobiology and co-author of the new paper, explained to me over the phone from South Carolina, where he was attending the Society for Integrative and Comparative Biology meeting. “It gives them a pretty cool repertory of tricks and tools they can use to adapt and acclimate.” The new find specifically helps to explain how octopuses have been able to flourish in tropical shallow seas as well as some 2,400 meters down, around the deep-sea hydrothermal vents off the coast of Antarctica.

Cephalopods, it turns out, seem to be doing a lot of RNA editing, Rosenthal says. And probably for good reason. Animals with the same basic DNA makeup can use RNA editing to fine-tune various processes, such as communication among neurons. As opposed to a hard-wired genetic mutation, RNA editing “gives you much better options because it lets you decide whether you want to use it,” Rosenthal explains. Not only that, but “you can decide how much you want to edit, so you can have a graded response.”

Rosenthal and his colleague Sandra Garrett, a doctoral researcher at the University of Puerto Rico, found that octopuses are using RNA editing to adapt to the temperature of the water around them. We warm-bloods don’t have to worry much about temperature affecting our neurons because we keep our bodies at a nice steady 37 degrees Celsius. But for poikilotherms, such as octopuses, temperature differences can wreak havoc on their neural networking. Communication in the nervous system—for movement and thought—is controlled by the rapid pace of neuron firing. A sodium-ion channel starts the firing and a potassium-ion channel shuts it down. Both of these functions slow down in cool temperatures—to say nothing of the 1.8-degree Celsius waters that the Pareledone octopus lives in—but the potassium portion slows down much more than the sodium side. So without something to balance these functions out, the neural signals could get thrown way out of whack. At the nearly freezing Antarctic temperatures, “channels would open about 14 times slower and close about 60 times slower” than they typically do among their warm-water Octopus vulgaris cousins, Rosenthal and Garrett explained in their paper. And that’s where these animals’ RNA editing comes in handy. One of the Antarctic octopus’s editing locations (I321V) “more than doubled the rate” of the potassium channel’s closing, which, along with other editing tweaks, would help bring the two channels closer to the same rate, the two researchers noted in their paper.

Rosenthal and Garrett checked other species of octopuses to see if they had the same pattern of RNA editing to control neuron firing for their respective temperature environments. Sure enough, two species of Arctic octopus, collected from water temperatures that approached 0 degrees Celsius, and two species of tropical octopus, collected in waters off Puerto Rico and Baja California, also showed extensive editing of the I321V area—as well as plenty of other edits.

Temperature adaptation is probably just one small piece of octopuses’s use of RNA editing to respond to their environment, Rosenthal says. They could “change protein function for anything: starvation, heat stress, learning—I think these are all plausible.”

Octopuses and squid seem to be particularly promising animals in which to study RNA editing. Although the process has been found in organisms ranging from coral to humans, most scientific searches for editing sites turn up just tens or hundreds after a scan of thousands of locations. In the cephalopods, however, Rosenthal and Garrett have already found some 100 editing sites just by looking at eight messenger RNAs. “The cephalopods have really taken the editing to heart,” Rosenthal says.

In fact they even seem to be editing the editing RNA, which makes for an even larger diversity of editing enzymes. This meta-editing could be a clue as to how these invertebrates, whose mollusk relatives include snails and scallops, became so bewitchingly complex.

Illustration courtesy of Ivan Phillipsen

A jawfish (indicated by the red arrow) hides among the arms of a mimic octopus. Courtesy of Godehard Kopp

Mimic octopuses (Thaumoctopus mimicus) have one-upped their well-camouflaged cousins by actively impersonating other sea creatures—such as venomous sea snakes and lionfish—by changing their body shape and movement. But they have now been one-upped by a tiny fish that mimics them (or at least takes advantage of their complex patterning and movement to better camouflage itself).

A black-marble jawfish (Stalix histrio) was spotted last July in Indonesia swimming among the arms of a mimic octopus. The encounter, which was filmed by Godehard Kopp of the University of Gottingen, was described as “opportunistic mimicry” last month in a paper in Coral Reefs.

“There are some cases in which many species mimic the same model,” Luiz Rocha, of the California Academy of Sciences, explained to me via email. But as far as a mimic-inspired camouflage behavior, “this is a first,” he says.

Why do the researchers think the fish is mimicking the octopus—and not the original model, such as a lionfish or sea snake? “The jawfish matches the color of the mimic octopus, but it only gains protection when it swims beside the octopus,” Rocha says. “So, if the jawfish was just sitting over open sand it probably wouldn’t look like a lionfish.” The shy little jawfish, which spends most of its time hiding in burrows in the sand, seems to be taking advantage of the advanced disguises of the bigger, bolder octopus, darting around its stripped arms—a strategy that could easily mask it to visual predators.

Plenty of organisms have disguised themselves to look like other, less appetizing objects (take a walking stick insect or a viceroy butterfly). And other fish have been observed engaging in such opportunistic mimicry (such as the bluestriped fangblenny, which masquerades as a cleaner wrasse when they inhabit the same waters). But researchers have puzzled over how complex behavioral mimicry adaptations might have evolved. This newly described mimic-mimic might offer some clues. “My best guess is that the color came first, and the behavior of following the octopus came later,” Rocha says. “After many generations the ones that resembled more the octopus pattern probably had a better chance of survival and of leaving more offspring.”

Rocha and his colleagues still aren’t sure how often these copycat fishes follow the octopuses—whether they’re a frequent tagalong or just an occasional accessory. “Mimicry is a fascinating subject and there is not much known about it in the oceans,” Rocha says. And, he says, “we plan to study this—and other cases—in much more detail.”

Video courtesy of Godehard Kopp

Illustration courtesy of Ivan Phillipsen

The deep-sea hydrothermal vent octopus discovered near Antarctica. Courtesy of Oxford University

Recent expeditions to Antarctic seafloor vents have yielded haunting new images of hairy-bellied yeti crabs, a seven-armed starfish and an eerily pale octopus—its curling arms encased in almost translucent skin.

This octopus, along with the dives’ other finds, were documented via ROV (remotely operated vehicle) and described earlier this week in PLoS Biology.

“The first survey of these particular vents, in the Southern Ocean near Antarctica, has revealed a hot, dark, ‘lost world’ in which whole communities of previously unknown marine organisms thrive,” Alex Rogers, a professor in Oxford University’s zoology department who led the team, said in a prepared statement.

The octopus, found at 2,394 meters below sea level (nearly a mile and a half down), of course, isn’t the first deep-sea—or the first vent-dwelling—octopus to be discovered. But it shares the same ghostly pallor as others that have been observed at similar depths. Why would these creatures, whose shallow-water cousins are so famous for their flamboyant camouflage, be slinking along as pale as a ghost?

As Janet Voight, a curator at The Field Museum in Chicago, explained to me this summer, deep-sea octopuses have little need for color or camouflage. In their dark worlds, neither predator nor prey is likely to see them. (For the same reason, these octopuses often don’t bother with an ink sac—no need for a fancy visual get-away tactic in a land without light.) She has observed many of these pallid creatures over the years through her work with the ROV ALVIN, and in 2005 she even described a veritable “feeding frenzy” of a dozen pasty Pacific Ocean hydrothermal vent octopuses (Vulcanoctopus hydrothermalis) at some 2,620 meters down.

In her office, Voight has shelves and shelves of deep-sea octopuses preserved in jars—some stored singly and others smushed several to a container—collected from her expeditions. Almost all of them were about the same non-color, off-white hue. Many of her specimens had short, stubby arms and had lived primarily in the icy-cold water column near, rather than on the ground near piping-hot vents.

The team that discovered the new Antarctic sea-vent octopus was able to film the new eight-armed bottom-dweller on the go. “The back four tentacles sort of shuffle like the treads of a tank, while the front four feel in front of the octopus,” Jon Copley, of the University of Southampton’s National Oceanography Center and co-author on the new paper, told National Geographic. This form of locomotion isn’t uncommon for octopuses that are on the prowl for dinner (possibly a tasty yeti crab or two?). And it makes plenty of sense for an octopus that lives in constant darkness would have to rely on touch—even more so than those that feel around rocks for food in sunnier environments—to catch a meal. But this shuffle was apparently too speedy for the research vehicle. “We weren’t able to collect any specimens—they were quick and rare—but they’re quite possibly a new species,” Copley said.

Even for researchers accustomed to unfamiliar sights, the white octopus and other unusual creatures were enough to give them pause. “These findings are yet more evidence of the precious diversity to be found throughout the world’s oceans,” Rogers said. “Everywhere we look, whether it is in the sunlit coral reefs of tropical waters or these Antarctic vents shrouded in eternal darkness, we find unique ecosystems that we need to understand and protect.”

Illustration courtesy of Ivan Phillipsen

An octopus walks (awkwardly) over land, courtesy of YouTube/tuantube

The slimy-looking cephalopod, captured in a rare video crawling over land, has many people (queasily) asking whether such bizarre-looking behavior is unusual for these animals.

The video, recorded at the Fitzgerald Marine Reserve in San Mateo County, California (originally uploaded in June but promoted earlier this week on Boing Boing), shows an octopus laboriously lugging itself over a tidal area before disappearing back into the water.

I checked in with Julian Finn, a senior curator of marine invertebrates at the Museum Victoria in Australia, and James Wood, a marine biologist and curator of The Cephalopod Page, to see what they thought about this slinking cephalopod.

“Crawling along out of water is not uncommon for species of octopus that live in the intertidal or near shore,” Finn says. Wood has seen several different species of octopuses getting around this way in the course of his research. As he points out, however, most species of octopuses are nocturnal, so we humans are less likely to catch them creeping out of the ocean.

Why would an octopus struggle across land, when its boneless body seems so unfit for moving out of water? For the chance to find some tasty shellfish and snails, most likely. When the tide goes down, “many octopus species emerge to hunt in the pools of water left behind by the receding tide,” Finn notes.

The crab shell that the octopus drops midway through the video might be evidence of this dinner motive. “Octopuses often carry prey items when foraging, returning to their lairs to consume them,” Finn says. “It is possible that the octopus in the video was either finished consuming the contents of the crab or was too tired to continue carrying it on land.”

After an octopus has cleared one tidal pool of food, it will often then haul itself back onto land in search of the next pool, which, Wood notes, it might be able to spot visually, or detect ahead with its outstretched arms.

Lurching onto land can also be an escape tactic if a pool-hopping octopus senses danger, such as, Finn notes, “a larger octopus.” Or a human, Wood says.

“Once while I was in Bermuda I was chasing and photographing a common octopus when it crawled out of the water, across eight feet of rocks and went back into the water,” Wood recalls. “If I was a fish instead of an air breathing mammal, I would not have been able to follow it.”

Octopuses themselves depend on water to breathe, so in addition to being a cumbersome mode of transportation, the land crawl is a gamble. “If their skin stays moist they can get some gas exchange through it,” Wood notes. So in the salty spray of a coastal area they might be okay to crawl in the air for at least several minutes. But if faced with an expanse of dry rocks in the hot sun, they might not make it very far.

Illustration courtesy of Ivan Phillipsen

Pigmented Japetella heathi, courtesy of Sarah Zylinski, Duke University

Vivid videos have captured stunning shallow-water octopuses performing impressive feats of disguise—changing color and texture to match kelp, coral or the sandy bottom. But what need would a deep-sea octopod, who lives suspended in dim light and darkness, have for fancy disguises?

Plenty, according to a new study published online Thursday in Current Biology. Octopuses living between 400 and 800 meters are faced with subtly changing light conditions that can mean the difference between life and death. In that zone, known as the mesopelagic, sunlight reaches some areas but not others, which means that best camouflage strategies for each needs to be strikingly different. Animals that live where a little light still filters down are better off taking a translucent approach, so that predators aren’t as likely to notice their silhouettes. But travel down farther, and the primary source of light is bioluminescence emitted by other animals, for which a black or deep red coloration is more ideal for reflecting these wavelengths of light.

The trouble for many octopus and squid living in that watery dim is that they can move hundreds of meters vertically, and “the boundary between environments where one or the other strategy would be most useful is nether sharp nor fixed, changing with factors such as time of day, cloud cover and turbidity,” write the study authors, Sarah Zylinski and Sonke Johnsen, biologists at Duke University.

Clear and pigmented Japetella heathi, courtesy of Sarah Zylinski, Duke University

One tiny species of octopus living in this ever-changing environment, Japetella heathi, can apparently switch its appearance from translucent to pigmented at the drop of a hat—or, to be more precise, the flash of a light beam. The researchers saw that with ambient dim light the 80-millimeter-long octopods were placidly translucent. But when a menacing, bioluminescent-like blue light was pointed toward them, they rapidly became opaque (by expanding pigment-giving cells known as chromatophores). As a last-ditch effort when the light didn’t vanish, perhaps sensing that their color-changing had failed to elude the presumed predator, the little octopuses tried an “evasive response,” pulling their head into their body. When faced with a red light or a passing overhead object (to mimic a potential predator swimming overhead), the little octopods were not phased and remained translucent. That suggests that this color changing “is not a generalized response to visual threat,” but rather a rather specific adaptation to certain predators and light conditions.

Zylinski and Johnsen found that a species of squid that lives in the same zone (Onychoteuthis banskii) was also able to quickly switch from clear to colored in a no time at all. The similarity is a striking example of convergent evolution: “In this vast three-dimensional wilderness…where sunlight is low or nonexistent, food is scarce, and mates are hard to find,” they noted, “we see shared solutions in the face of shared problems.”

Friendly octopus I met at a robotics lab in Italy. Credit: Katherine Harmon

Chimps wield tools, chameleons change colors, and dogs can recognize their owners. Octopuses, as it turns out, are adept at all of the above. Not too shabby for a solitary, spineless marine creature, eh? In fact, octopuses (yes, that is the preferred pluralization) are inspiring riveting research in everything from biology to robotics and from neuroscience to defense technology.

As an associate editor at Scientific American, I try to sneak animal-oddity stories to my health and life sciences coverage whenever I can. A couple of years ago I blogged about octopuses that use coconut shells as portable protection (after being transfixed by the video of the animals awkwardly carrying these hilariously large hulls), a finding which many biologists consider to be the first evidence for tool use by an invertebrate. From that post—with guidance from a fantastic literary agent—a book idea was born.

Since then, I have immersed myself in all things octopus for the book, which will be published by Penguin’s science imprint, Current, in a year or two. In the meantime, cephalopod scientists are doing great research that is just too fascinating to set aside for later.

This blog, as a precursor to my octopus opus, will feature the latest and greatest science news from the octopod world as well as tales of occasional adventures—and misadventures—from my worldwide travels to learn about these weird and wonderful animals.

Enjoy!

Illustration courtesy of Ivan Phillipsen