Cephalove

A story about squid has been making the rounds in news sources and blogs this weekend. Just two days ago, a paper came out showing that male squid (loligo peleii) react with extreme agression to a certain protein found on the surface of squid eggs. The paper was written by a group of researchers (including the illustrious cephalopod biologists Jean Boal and Roger Hanlon) from all over the world.

The authors of the study noted that, when this species of squid get together in big groups, the males interact with the eggs that the female attach to the sea floor in a curious way – they approach eggs that are already attached to the sea floor, blow water on them, and then touch the eggs with their head and arms. This occurs before and in-between fights that the males have with each other, in which they compete over the opportunity to mate with females.

To confirm that some component of the eggs was causing the squid’s aggression, the experimenters put pairs of male squids into tanks with eggs. Sure enough, touching the eggs made the squids more aggressive.

Squid eggs attached to the seafloor, by Debby Ng

The authors then made an extract of the squid eggs, and used a technique called high-performance liquid chromatography to separate their extract into different parts. HPLC works by forcing a solution through a tube (called an HPLC column) that the various substances in the solution stick to in some way. Depending on the specific conditions, different substances will get stuck in the column for longer or shorter times. Substances that don’t stick to the column very well come out the other side quickly, and substances that stick to the column very well will come out more slowly. The solution coming out of the column at a certain time will contain only some of the substances that were in the original solution, and so it is a useful way to separate a complex mixture up into parts, called fractions.

After the egg extract was divided up into fractions, the various fractions were tested to see if they made males aggressive. After finding which fraction was responsible for this effect, the authors purified it further and identified a specific protein within it and figured out its amino acid sequence.

The culpit, it turns out, is a small protein that is related to a family of proteins called the Beta-microseminoproteins, which have been found in species from humans to scallops to ostriches. The female squid’s reproductive tract secretes this protein as part of the coating of the eggs she lays.

In humans, this group of proteins is found in the male reproductive tract, where it attaches to the outside of sperm cells and may be related to a man’s level of fertility. Nobody has asked whether it also makes males of mammalian species more aggressive, although I suppose it is only a matter of time now.

How could the behavior we’re looking at (that is, the fact that males of the species L. pealeii just flip out when they sense this protein) be good for the squid? Behaviors have to evolve, and so they need to help the individual to reproduce in some way.

It’s easy to see how being aggressive and competitive would help a male mate. The real question is: why use a pheronome? And why on the eggs? In a squid mating frenzy, there is ample stimulation – why don’t male squids simply become intensely aggressive at the site of a large group of other squid? That would seem to involve less energy (and less evolutionary backflips) than first seeing the mating frenzy, then seeing the eggs on the seafloor, then approaching and touching them, and only then being spurred into super-aggression.

For starters, it’s good to remind ourselves that none of the components of that behavioral sequence, odd as it is, evolved specifically for that purpose. Because the type of protein that is used as a pheremone in this case is found in many animals, it very clearly has been around for a long time before squid evolved specific mating habits, filling other necessary (and currently unknown) functions. Similarly, squid were probably spawning in groups and competing for mates before they developed the ability to respond to this protein with aggression.

Of course, this could be wrong – if it turns out that beta-microseminoproteins is used as a pheremone in lots of different species, then it may have evolved this function very long ago. Only more research will tell.

Functionally speaking, though, why would a pheremone evolve as a cue for aggression, even when there are plenty of other cues in the environment for the male squid to respond to (the sight of eggs and other squids being the easiest to think of)? My thought is that, in a system that can change as quickly and as unpredictably as an ecosystem, it always helps to have reduntancy. Having two seperate senses that both cause the right behavior in the right context is better than having just one, because either one might fail at an inopportune time and leave the animal (figuratively) screwed.

The other idea that I came up with is that it might help the squids recognize when a spawning group is made up of the right kind of squid – squids of their own species or sub-species. There are many types of squid that look alike to me, and while I’m sure that squid are better at telling the difference between their own kind than I am, it seems like a relatively easy mistake to make in poor conditions (dark or murky water, or the added confusion of predators being present.) Any squid who couldn’t clearly tell when the squids available for mating were squid they could actually produce offspring with would be at a huge disadvantage in terms of making babies. Again, this question could only be answered with more research.

Thanks for reading!

Scott F. Cummins, Jean G. Boal, Kendra C. Buresch,, Chitraporn Kuanpradit, Prasert Sobhon,, Johanna B. Holm, Bernard M. Degnan, Gregg T. Nagle,, & and Roger T. Hanlon (2011). Extreme Aggression in Male Squid Induced by a b-MSP-like Pheromone Current Biology : 10.1016/j.cub.2011.01.038

Anahí Franchi N, Avendaño C, Molina RI, Tissera AD, Maldonado CA, Oehninger S, & Coronel CE (2008). beta-Microseminoprotein in human spermatozoa and its potential role in male fertility. Reproduction (Cambridge, England), 136 (2), 157-66 PMID: 18469041

Cephalopods have a lot to offer – tentacles, beaks, and big scary (and perhaps cute) eyeballs. Today, though, let’s look at a part of the cephalopod body that doesn’t get paid so much attention to, especially by us neurobiologist types: the ink.

Fossil squid with preserved ink sac. Ink sacs are often easily visable in coleoid cephalopod fossils. (via Maitri on Flickr - click through for original.)

Most coleoid cephalopods (that is, all the living cephalopods excluding nautiluses and a few deep-water octopuses) produce ink. This ink is composed chiefly of melanin, which is a dark brown pigment that is found throughout the animal kingdom. Humans have used cephalopod ink for a variety of purposes, including writing, drawing, dying, and cooking (the fact that both a dark brown color of ink and a genus of cuttlefish are both named Sepia is not coincidence.) In fact, you can buy tubs of cephalopod ink online.

Cephalopods use their ink for a different purpose, though; it helps them get away from sticky situations. When severely startled, cephalopods will release ink from their ink sac, which is pushed out of their funnel with a jet of water (which usually also jets the cephalopod in the opposite direction away from the perceved danger.) The resulting cloud of ink could serve many functions; it could conceal the escaping cephalopod’s location from the predator, serve as a false target for the predator (who would attack the dark ink instead of pursuing its prey,) frighten the predator, or even trick the predator’s sensory systems into thinking it had already caught something (I’ll explain this last one at the end of the post.)

One neat property of cephalopod ink, though, has nothing to do with how predators perceive it, but rather how cephalopods perceive it.

When one squid in a shoal inks (“inking” being the action of expelling ink into the water) the rest of the shoal can certainly see what has happened and be alerted to the immanent danger that way. In addition to this, though, it has been hypothesized that squid can chemically sense the ink in the water, which would give them another way to keep abreast of squid-predator interactions going on around them.

One study that found evidence for this hypothesis (which is actually a part of a series of studies in this line of research) was done by Gilly and Lucero (1991) at Hopkins Marine Station in California. These investigators restrained squid (loligo opalescens) by attaching their dorsal mantle to a platform with cyanoacrylate glue (the same stuff that Super Glue is made of,) and then used a pipette to place small amounts of various substances onto a chemoreceptive organ located behind the squid’s eye.

Photograph and photomicrograph of squid olfactory organ - from Gilly and Lucero (1992)

They recorded the activity of the squid with a video camera, and everything was done remotely, so that the movement of the experimenter’s would not upset the squid and cause extra escape-like behavior. Escape-like behavior was measured in terms of the pressure inside the squid’s mantle, which was recorded via a tiny pressure transducer inserted inside the squid’s mantle. One of their records is shown here – the spikes in pressure reflect jets of water being expelled from the squid’s mantle, as it presumably attempts to escape from the chemical stimuli that signal some sort of danger in the environment.

They found that pipetting ink from an animal of the same species of the test animal onto the olfactory organ caused jetting. Furthermore, they found that a specific component of squid ink, L-DOPA (which is a precursor of melanin, the main pigment in squid ink) caused jetting just as much as did whole ink. On this basis, the authors concluded that L-DOPA is used as a sort of chemical alarm signal between L. opalescens individuals. (I should note that some of the authors cited in this post write that squid ink is actually a cue, not a signal, as a signal results in an action on the part of the receiver that benefits both the receiver and the sender of the signal. Escape responses by squid in response to the ink of conspecifics do not fit this definition.)

A more recent study by Wood, Pennoyer, and Derby (2008) looked at the responses of Caribbean reef squid (Sepioteuthis sepioidea) to squid ink preparations. This species of squid has ink that hangs together in a mucous-ey glob in the water, forming what the authors call a “psuedomorph”, or false animal shape that confuses predators.

Each squid was tested by placing a small amount of an ink preparation into its aquarium and videotaping its behavior during and after this event. The authors used a scoring system to determine how defensively each squid behaved during each test, with points on a scale of defensiveness being awarded for behaviors like jetting, specific postures that are used to hide from predators, and certain color changes that are known to signal alarm. A higher score on this measure of defensiveness indicated that the squid was “alarmed” (or something like that) during the test. Below is a video showing on of their tests, produced by New Scientist:

The authors found that S. sepioidea responsed with alarm to fresh squid ink placed in their aquarium. The ink worked to cause alarm responses even after it had been frozen, albeit not as well – the authors noted that it changed in consistency, and dispersed much more quickly. Ink that was placed into an adjacent aquarium (meaning the squid could see it, but could definitely not chemically sense it) worked very well to stimulate escape behavior. This argues that one of the stimuli that this species of squid uses to respond to ink is its appearance. What about chemoreception, though?

The authors produced “melanin-free ink” by centrifuging fresh ink to remove all of the melanin-containing granules in it. They reasoned that this ink was just link the whole ink chemically, except that it did not contain the specific chemical that made it opaque (melanin). They found that the squids did not respond to this ink that they could not see. These results point to the use of vision exclusively in S. sepioidea in responding to other squid’s ink, apparently conclusively.

Frustratingly, they don’t, really. It would be easy enough to chalk this result up to species differences – one species can chemically sense ink, and the other species cannot. These results, however, don’t say enough to make this claim (although there may exist other research that answers this question.)

In a paper by Lucero, Farrington, and Gilly (1994), squid (L. opalescens) ink was analyzed for the presence of L-DOPA and dopamine (they found it, but that’s not the reason I mention it.) They found that, in seawater, L-DOPA and dopamine are rapidly degraded via oxidation reactions, which would certainly dampen any effects they would have on the behavior of squid swimming in that water. They also found that the L-DOPA and dopamine in squid ink did not degrade this rapidly – these preparations behaved as if they were being protected by some sort of antioxidant contained within squid ink. While the authors used ascorbic acid (a small, soluble molecule) to replicate this effect, it’s possible that any anti-oxidant activity in the squid ink is provided by a protein (or another large, centrifuge-seperable molecule.) When Wood et al. prepared their “melanin-free ink”, they may also have removed some component of the ink that is essential for its activity as a chemical signal (for a hypothetical example, a protein that prevents that oxidation of L-DOPA and dopamine in the vicinity of the ink blob.) They may even have done something that eliminated the L-DOPA and dopamine altogether – they provide not chemical analysis of their ink preparations, and so it’s hard to know. The authors acknowledge that this is a shortcoming of their work in their paper, so there’s been no oversight on their part – it just would have been nice if they’d done a bit more in the way of quantifying the chemistry of the preparations they were using. Oh well – it’s something for the next round of studies, I guess.

I mentioned that squid ink might trick predators into “thinking” they had already caught the squid and were eating it, a trick called phagomimicry. This is because squid ink (and the exudates that other molluscs exude under stress) contains, among other things, a full complement of free amino acids – these are chemicals that predators taste when they eat flesh. If a predator gets a mouthful of ink, if they can sense the amino acids that normally tell them that they’re eating flesh, they may behave as if they have already caught and/or eaten their prey, and give up pursuit.

Thanks for reading!

W. F. Gilly and Mary T. Lucero (1992). Behavioral Responses to Chemical Stimulation of the Olfactory Organ of the Squid, Loligo opalescens Journal of Experimental Biology

WOOD, J., PENNOYER, K., & DERBY, C. (2008). Ink is a conspecific alarm cue in the Caribbean reef squid, Sepioteuthis sepioidea Journal of Experimental Marine Biology and Ecology, 367 (1), 11-16 DOI: 10.1016/j.jembe.2008.08.004

Lucero, M., Farrington, H., & Gilly, W. (1994). Quantification of l-Dopa and Dopamine in Squid Ink: Implications for Chemoreception Biological Bulletin, 187 (1) DOI: 10.2307/1542165

You know you’re a blogger when you write your first post about blogging. I guess it was inevitable.

I came upon Dr. Royce Murray’s article “Science Blogs and Caveat Emptor” today (via Chembark via Everday Science, and also covered at In the Pipeline, Terra Sigillata, InSightu, with a great comment by B. Penders, and Science 2.0). Needless to say, it rubbed me a bit of the wrong way, and before I knew it I had typed up a response. Here’s the email that just left my tower and headed for his inbox:

Dear Dr. Murray,

I came upon your article in the most recent edition of “Analytical Chemistry” today via Paul Bracher’s response to it at his website (http://blog.chembark.com). As a student, a scholar, and a science blogger, I was a bit chagrined to read your pessimistic characterization of science blogging as an enterprise (and by extension, of science bloggers as information producers.) In particular, you imply that science bloggers write “without the constraint of truth,” in contrast to more “traditional” forms of public science communication whose writers, you seem to presume, are primarily driven by their noble intentions to impart accurate scientific knowledge to the public. In truth, however, this is a broad mischaracterization of science bloggers, who are for the most part very concerned with the truth and completeness of what they write (and are in many cases disillusioned with the popular press’s coverage of science, which is often sensationalist, vague, incomplete, or downright wrong.)

That most bloggers are not professional journalists, and almost all “traditional” science journalists are (importantly, they professional journalists and not professional scientists) is, if anything, a factor that constrains the world of science blogging more closely to scientific veracity that the world of “traditional” science communication. Because science bloggers generally do not sell their work (in fact, many that I’ve encountered consider this antithetical to the activity of blogging,) they are under little pressure to sensationalize the topics they cover, or to leave out important information that might be considered to complicated or too uncomfortable to include in “traditional” science media. Because there is no other way to assess the qualifications of a blogger, it is a common (though not ubiquitous) practice for science bloggers to be very transparent about their identities and qualifications, as well as their sources. The conclusion that this diminishes the credibility or trustworthiness of bloggers is based on a misunderstanding of how blogs (and blog readers) actually work.

When viewing blogs, readers are encouraged to understand the source of their information (often in the form of links and references to scientific publications) instead of just accepting it as truth because a journalist has told them that it is true. If “traditional” media outlets did this as a rule they would be, by economic principle, damaged; by giving up their place as the public’s ultimate source of information, they give up some portion of the salable value of their services. Science bloggers, on the other hand, whose work is valued in terms of its circulation among readers, its esteem among fellow bloggers, and the feedback it garners from readers, have everything to gain by providing correct information, specifying where they got it, and accurately describing how the scientific method was used to produce that knowledge (and often, how it failed – something “traditional” science communicators stay almost completely silent on.) Because there are few financial incentives to keep science bloggers blogging, the community of science bloggers is made up of people who do what they do because they are committed to providing quality information about science to the public (or some segment of the public.) Bloggers are held accountable to the reasonableness and truth of their portrayal of science, because accuracy and informativeness are the capital of the blogging world. Fact-checking is done by bloggers, and then again by their readers (many of whom are also bloggers.) In the end, sources are provided, so that readers can easily do their own fact checking. It is this attitude, one of healthy skepticism, transparency, and reference to the scientific process, that science blogging engenders in its readers – this contrasts with the general lack of effort in “traditional” media to actively engage their audiences in the knowledge they present rather than maintaining an unquestioned, one-way flow of information from the publication to the reader.

In sum, I support your conclusion – information consumers do need to question the source of their information. I believe, however, that science blogs offer an accessible public forum where information consumers can question the sources of the information that they would otherwise only get in the form of brief, often sensationalized press-release and popular newspaper and magazine articles. As evidence by your support of the peer-review process, you seem to have great faith in the power of transparency and debate to generate reliable information – it puzzles me as to why you are so suspicious of this same process when it is enacted in public, where there are no formal restrictions determining who can participate, and where there are, if anything, fewer competing financial and professional interests than in either the world of science journalism or the world of professional scientific publishing.

I will be publishing this letter in full on my blog ( www.cephalove.southerfriedscience.com ) . If you decide to respond and you would not like your response published, please state as much.

Thanks for your time,

– Michael Lisieski

www.cephalove.southernfriedscience.com
mike.lisieski (at) gmail.com
xxxxxxxx (at) buffalo.edu
(xxx) xxx-xxxx

Everybody likes cuttlefish, it seems. They’re neat-looking, sociable, and display lots of entertaining behavior. I think it’s about time, then, to start talking about what cuttlefish do best: change color! I’ll start at what is, as far as I can tell, the beginning.

In 1988, Roger Hanlon and John Messenger published a paper called “Adaptive Coloration in Young Cuttlefish (Sepia Officinalis L.): The Morphology and Development of Body Patterns and Their Relation to Behaviour.” This paper lays out a description of the body-patterning behavior of young cuttlefish (S. officinalis), paving the way for many future studies on this behavior and the environmental features mediating it. The authors hatched and raised “more than 50″ cuttlefish, recording their behavior while they were in the laboratory, and then releasing them into the sea and videotaping them. From this (very large) set of data, they developed a systematic description of the various components of cuttlefish body patterns, as well as some ideas about what adaptive function they serve to the cuttlefish to use them. In addition, they did some microscopic analyses of the animal’s brains and skins, which I will spend less time on here.

The authors decided, based on precident as well as their own ingenuity, to describe the body patterns of cuttlefish (that is, the patterns of postures and colors that cuttlefish display) using a hierarchical scheme. In this scheme, each body pattern corresponds to one or a few behaviors, during which it is expressed. The body pattern is itself composed of multiple components – it has chromatic components (specific patterns of coloration,) textural components (specific patterns of skin texture,) postural components ( specific ways the cuttlefish holds its body,) and locomotor components (the ways the cuttlefish moves its body during the display.) Each of these components is made up of several units. The term “unit” as used here refers to a group of muscles that acts together to produce a local effect, many of which add up to become a body pattern component. For example, the group of muscles in each arm that hold that arm in a certain position make up a postural unit, and all of the postural units (that is, all of the arm and mantle muscle groups) together make up a postural body pattern component. Each unit is in turn made up of a number of elements, which are the smallest possible pieces that can display a particular tiny piece of a body pattern – for example, a single arm or skin muscle, or a single chromatophore. If that confused you, just take a look at their first figure, diagramming this concept:

Click through for a larger version.

The authors identify 54 components in all: 34 chromatic components, 6 textural components, 8 postural components, and 6 locomotor components. They also identify 13 distinct body patterns that are made out of these components: 6 chronic patterns (those expressed stably for a long time) and 7 acute patterns (those expressed transiently, usually in reaction to some significant or disturbing event.)

As an aside, I’d like take a moment to throw around a few counter-arguments to a common abuse of this line of research – namely, the claim that people like to throw around that cuttlefish and squid have a “language” that they express with their skin.

Firstly, cuttlefish displays are not symbolic – a cuttlefish who displays (for example) a pattern associated with mating is symoblizing sex, or the desire to have sex – the fact is that cuttlefish that want to have sex behave in a particular way. Calling this language is like saying that your dog is speaking to you when he humps your leg. He’s not telling you that he wants to have sex – he’s just doing what amorous dogs do.

Secondly, cuttlefish displays do not seem to have syntax. One of the things that makes language useful, and indeed defines language, is the ability to use various components of that language in novel ways, to communicate novel ideas. Related to this is the fact that the meanings of symbols are arbitrary – they can change, and do not neccessarily resemble or otherwise relate to whatever is being symbolized. There is simply no evidence that cuttlefish body patterns are this flexible, or ever mean anything besides making the behaviors they are part of more distinctive or effective. They may serve as an avenue of communication between conspecifics in some instances (in fact, they almost certainly do) but it is woefully inaccurate to describe them as language, especially without any further qualification.

Even if cuttlefish body patterning were a language, it would be a poor one. In most languages, a small number of symbols are used in various combinations to make a variety of units of meaning. For example, letters combine to form words, which combine to form short phrases. In english, there are 26 letters and many thousands of words and short phrases. Combining letters generates new information, not contained in the individual letters. The transition from components to body patterns in cuttlefish, on the other hand, causes information to be lost. Out of many components, cuttlefish put together only a few units of meaning.

So dear internet: I know how much you love cuttlefish, and I know that you want everybody else to love them, too. Exaggerating the evidence to make them seem more “intelligent” is not a valid way to do this, and makes you look unintelligent, dishonest, or both. Please, for your own good and the good of cephalopods everywhere, stop.

Anyways, back to the paper:

What do cuttlefish use these body patterns for? Most of the chronic body patterns are used for crypsis, or camoflage. A cuttlefish will use these patterns to blend into whatever is around them, so that they don’t get eaten. The plate below shows three cuttlefish in different developmental stages blending into the same substrate. The youngest one (towards the bottom of the photograph) is showing (as well as I can tell) a “strong disruptive” pattern, made up of highly contrasting dark and light components. The next oldest one (towards the top of the photograph) is showing a “weak disruptive” pattern, with the same basic scheme but with less contrast. The oldest one (right in the middle) is showing a “dark mottle” pattern, which is just what it sounds like:

When hiding fails, cuttlefish will show a variety of acute patterns in defense. Included among these are “uniform blanching” and “uniform darkening”, both of which are used to confuse would predators. A posture called “flamboyant”, where the cuttlefish waves its arms in the water, is used to startle predators. Adult cuttlefish use a pattern called the “deimatic” pattern, where the cuttlefish flattens and turns completely white except for a few dark markings on the mantle is theorized to be a sort of bluff: it makes the cuttlefish look bigger, and (hopefully) frightenes whatever predator is pursuing the cuttlefish enough to drive it off.

Patterns called “zebra” and “intense zebra” are used in social behavior, which primarily consists of sexual behavior and agonistic behavior (fighting or aggressive displays.) Variations on these patterns are used to distinguish between males and females. The picture below shows a male displaying the “intense zebra” pattern to a female. The authors note the critical inclusion of the extended and densely patterned fourth arm (the one most towards the bottom of the photograph,) the absence of which is one of the things that distinguishes the female “zebra” display from the male “zebra” display.

Click through for a larger version.

Finally, (and this is what I like best about this paper,) the authors close with a call for work “towards a comparative cephalopod ethology.” I can’t say it any better than they did:

It is clear from our work and [others] that cephalopod body patterns are inextricably linked with cephalopod behaviour so that study of body patterns becomes central to cephalopod ethology…

Recently there has been increased interest in ecological studies of cephalopods and we hope field researchers will begin to record systematically ethological data such as adaptive coloration, with the long-term goal of providing a more comprehensive view of their behaviour and life style.

Thanks for reading! I only covered this paper in the roughest way, so I urge those who want to know more to check it out – it’s available from Royal Society Publishing.

Hanlon, R., & Messenger, J. (1988). Adaptive Coloration in Young Cuttlefish (Sepia Officinalis L.): The Morphology and Development of Body Patterns and Their Relation to Behaviour Philosophical Transactions of the Royal Society B: Biological Sciences, 320 (1200), 437-487 DOI: 10.1098/rstb.1988.0087

Here at the Southern Fried Science Network, all of us bloggers have been charged to post articles dealing with ocean-related pseudoscience as part of SFSN’s first “Ocean of Pseudoscience Week.” Since I try to keep this blog firmly focused on cephalopods, I was at first antsy that I would not find anything to write about. However, the (sometimes distressingly) wide pool of information that is the internet has not disappointed me.

You’ve all heard about Paul the Octopus by now. A Google search for “Paul the Octopus” (the exact phrase) turns up 5.5 million results. A blossoming cephalopod enthusiast who is curious about Paul can pick from literally millions of sources of information to hear about this phenomenon, and if she’s smart, will try to pick one that seems credible. Like, say, a CNN news report. She would find some informative and entertaining quips, and would mostly get the facts straight. That is, until she got to the point in the article where the CNN reporter asks an “expert” the critical question:

“Can an octopus really be psychic?”

After reading this section, if she had any sort of head on her shoulders, our inquisitive internet reader would (hopefully) be aghast, and a bit miffed that a CNN report would be such a lousy source of information.

Before I go on, let me say that there are any number of highly qualified people who could of answered this question. There are several researchers who study cephalopod behavior and cognition who are generally pretty friendly, and besides that entire societies of researchers devoted to scientificially studying claims of the “supernatural”. CNN is supposed to be credible, right? They’re one of the big names in news, globally. But their reporter didn’t pick anybody who was an expert in the science and psychology behind “parapsychological” phenomena or an expert on cephalopods. Instead, he decided to interview Michelle Childerley (see her personal homepage), a self-proclaimed “Animal Communication Expert
Pet Psychic & Behaviour Specialist.” Her qualifications include thinking that she could talk to her pet dog as a child (who didn’t, though?), as is proclaimed on her “About” page:

Michelle felt since the age of seven that she was aware of a special connection with her dog Jason, her soul mate throughout her childhood. She always knew exactly what Jason was thinking and feeling and would enjoy endless conversations. After Jason was taken away at the age of twelve, Michelle shut down her intuitive awareness for many years to come.
It wasn’t until 2006 that Michelle became aware of her ability once again when the dog of a man selling the big issue suddenly spoke to her. In that moment a reconnection was established and Michelle then set out to bridge the gap between animal and human communication.

(As an aside: what is “the big issue”? I’d love to know.)

So what did Ms. Childerley have to say about Paul? You might have guessed what her take would be. From the CNN article:

Michelle Childerley, who describes herself as an animal communications expert, told CNN that all animals — as well as humans — possess a psychic ability, with telepathy the main way of communicating among many species. She says dogs can often sense what an owner wants before they vocalize it.
As for as Paul’s ability to predict a football result, Childerley claims the octopus is perfectly aware of what he is being asked. “He’s picking up on what everyone around him is thinking,” she said. “He knows there are two boxes which represent two sides, so he’s basically tuned in to the more positive team at the moment he makes his choice.”

Why care about this women and her claims about communications with animals? For one thing, she’s selling these claims to people as a sort of veterinary care, taking money both from misled pet owners and from legitimate practitioners (this is not to say she might not use some legitimate animal training procedures in some of her work, but she will also accept 30 pounds to do an “animal readings/consultations by an emailed or posted photograph”, which means that you send her some money and a picture of your pet, and she will tell you what’s wrong with your pet’s emotional/psychic life. Despite my small knowledge of the field of veterinary medicine, I am sure that this is not a legitimate veterinary care technique.) In addition, claims like hers serve to distract from and give a bad name to people who are trying to work on the sciences of animal communication and animal-human communication. It turns out that communicating with animals in a reproducible and useful way is much more difficult than being paid money to look at a digital image and coming up with a diagnosis and prognosis based on the feeling you get from the image. Pet psychics (especially those who bill themselves with sciencey-sounding titles like “Animal Communications Expert”) give a bad name to the scientists who are working hard to actually understand and explain animal communication and cognition.

The reporter might have redeemed the article if he’d presented any other opinions on the topic, or any indication that readers might want take this “expert’s” testimony with a grain of salt. Sadly, he didn’t. We’re left wondering whether he really took Ms. Childerley’s comments seriously, or if he’s just kind of bad at finding relevant people to interview.

To give credit and links where they are due, I first heard about this story at Boing Boing, where Maggie Koerth-Baker had the right reaction to it: a hearty facepalm.

Thanks for reading!

It has been known that cephalopods can respond to polarized light for some time – Wells did the work showing that octopuses can detect polarized light in the 1960′s, and it’s been studied in fits and spurts since then.  In the late 1990′s and early 2000′s (from what I can tell,) it became a relatively hot topic among researchers who study animal communication, because it appeared as if cuttlefish might be able to use polarized light for some sort of intraspecific communication.  A good though somewhat dated review of the topic is Shashar et al’s Polarization Vision in Cuttlefish – a Concealed Communication Channel? (1996).

How can cephalopods see polarized light?  It turns out that their photoreceptors are orientated at a variety of angles, so that incoming light will cause the most stimulation in photoreceptors that are oriented the “right” way.  In unpolarized light, all of the cells would be pretty much equally stimulated – nothing unusual happens here.  Upon being hit by polarized light, though, a specific population of retinal cells (those that are oriented in the proper direction) will be activated, and the animal will be able to see the polarization of light.

The top image is a cuttlefish as seen by the human eye. The bottom image has been given false color, so that areas which reflect polarized light show up as green.  On an unrelated note, cuttlefish sure are cute.

In addition to discovering the patterns of reflection of polarized light by cuttlefish skin, the authors found that cuttlefish respond differently to their own reflections when they view them through a filter that screens out polarized light.  Specifically, they found that cuttlefish responded less noticibly to the disrupted image.  While the authors declare that these findings are “fully consistent with the hypothesis that cuttlefish use controllable polarization patterns for intraspecific communication,” they are also consistent with the more parsimonious explanation that cuttlefish don’t respond to any stimulus made of non-polarized light as strongly as they do when it is at least partially polarized.  While the theoretical argument presented in this paper is interesting, I think it’s a bit too eager for what the data show.

Fast-forward to 2004: Boal et al. published a study called Behavioral evidence for intraspecific signalling with achromatic and polarized light by cuttlefish. In this study, they exposed cuttlefish (S. officinalis) to conspecifics (that is, other cuttlefish) through either a clear or a polarized light-blocking barrier.  They found that only females responded differentially to conspecifics behind the polarization-distorting barrier, not responding to them at all (cuttlefish confronting each other unexpectedly often show some sort of postural and color change.)  This was the only significant result that they found, and it is ambiguous in its interpretation.  Again, it might simply be that a non-polarized stimulus is not very interesting to an animal who is used to seeing a world of polarized light.

So, do cuttlefish use polarized light to communicate?  I’m not convinced.  It seems as if everybody’s hoping that it’s true, but th
ere’s not any good data showing it to be so.  I can’t sum it up any better than Mathger et al. did in their 2009 review:

The fact that cephalopods can detect polarized light
and can also produce changeable polarized light
patterns in their skin begs the question whether
cephalopods communicate using polarized light signals.
The likely answer is that they do. Unfortunately, we
have little evidence to support this statement.

Thanks for reading!

Shashar N, Rutledge P, & Cronin T (1996). Polarization vision in cuttlefish in a concealed communication channel? The Journal of experimental biology, 199 (Pt 9), 2077-84 PMID: 9319987

Mathger, L., Shashar, N., & Hanlon, R. (2009). Do cephalopods communicate using polarized light reflections from their skin? Journal of Experimental Biology, 212 (14), 2133-2140 DOI: 10.1242/jeb.020800

Boal, J., Shashar, N., Grable, M., Vaughan, K., Loew, E., & Hanlon, R. (2004). Behavioral evidence for intraspecific signaling with achromatic and polarized light by cuttlefish (Mollusca: Cephalopoda) Behaviour, 141 (7), 837-861 DOI: 10.1163/1568539042265662

Shashar N, Hagan R, Boal JG, & Hanlon RT (2000). Cuttlefish use polarization sensitivity in predation on silvery fish. Vision research, 40 (1), 71-5 PMID: 10768043