Archive September 2010

further ruminations on writing an essay Alison Campbell Sep 29

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This post’s triggered by the fact that I’ve just spent several hours reading through draft essays that students have asked me to check for them. I definitely don’t go through & correct every last thing, but I do identify areas that need work, & I’ll give examples of how to improve things. For example, I’ll re-write a paragraph as an example of how to tighten up a piece of writing, making it more concise without losing any of the information therein. And a lot of what I’ve said to my students is equally relevant to those of you intending to sit Schol Bio exams at the end of the year.

So far all the essays I’ve looked at have obviously been based on an initial essay plan. This is really good :) An essay plan allows you to identify the key points you’re going to make & the supporting evidence you need to include, plus you can make sure that your ideas flow well & there’s a logical progression of concepts through the essay. This makes it much easier to read & follow your argument, & from the point of view of the schol examiners it’s good evidence of your ability to synthesise ideas and concepts into a coherent whole.

An essay plan is thus a Very Good Thing :)

On the other hand, don’t make assertions that you can’t support. In the exam, your supporting evidence is often quite likely to come from the resource material that’s provided as part of the question. (This can be quite extensive, so take the time to read it carefully before you begin on your answer.) For my students, the evidence needs to come from the scientific literature.

For example, I’ve just read one essay where the student’s saying that both genetic drift & natural selection have played a part in modifying the frequency of a particular allele in a population’s gene pool. As far as I’m aware only one of these factors has had an effect – but I’m open to persuasion (& aware that I haven’t read every single resource the students have sought out. And believe me, they’ve done an excellent job of researching their topics). If a student can marshall evidence in support of their point of view then I’ll give credit for that, even if it wasn’t in my original marking scheme. After all, one of the skills I want them to develop is independence of thought, & that’s not going to happen if they have to toe the party line!

Punctuation matters! (For those who haven’t seen the wonderful ‘Dear John’ letters, where so much depends on where you put the commas & full stops, I’ll add it to the end of this post.) The examiner is looking for good communication skills, and that does include doing your best to ensure that you’re using good punctuation, grammar, & sentence structure. In a prepared essay, like those I’ll be marking next week, I do come down fairly hard on this – but I’m realistic enough to know that things will probably go a little to pieces for some people during the exams :)

So far every draft I’ve looked at has had a good introduction that’s clearly set the stage for what’s to come. And without any use of the phrase ‘In this essay I will discuss…’. I already know that, from the choice of essay topic (which has to be included on the cover page). In an essay with a restricted word limit, those are just wasted words. And in an exam, those words take time to write, & you could probably use that time more profitably. (That’s actually one reason we have a restricted word limit, because in the final exam our first-year students have only about 45 minutes in which to write an answer, so they’re not going to be writing great long screeds but they still need to cover all the key points. The term essay gives them practice in this.) But a word of warning – the conclusion should not be simply a restatement of the introduction! It really should be a concluding statement that highlights the key points you’ve made in the course of the essay, linking them to your main themes or reinforcing their significance.

Anyway, it’s rather late & I’ve got a lot of meetings tomorrow; I need my sleep. The ‘Dear John’ letters follow, for your delectation. My class thought them extremely funny :) I know which version I would prefer to receive!

Dear John,
I want a man who knows what love is all about. You are generous, kind, thoughtful. People who are not like you admit to being useless and inferior. You have ruined me for other men. I yearn for you. I have no feelings whatsoever when we’re apart. I can be forever happy–will you let me be yours?

Dear John,
I want a man who knows what love is. All about you are generous, kind, thoughtful people, who are not like you. Admit to being useless and inferior. You have ruined me. For other men, I yearn. For you, I have no feelings whatsoever. When we’re apart, I can be forever happy. Will you let me be?

evidence supporting an hypothesis of crank magnetism Alison Campbell Sep 27


Orac often talks about ‘crank magnetism’ – the tendency for people who believe strange stuff in one area, to be attracted to other areas of oddness as well. (As far as I can tell, the terms was originally formulated on the denialism blog.) Anyway, having an hypothesis (the above crank magnetism) one must test it – in this case, perhaps most easily done on an observational basis. ‘Letters to the editor’ are potentially a good source of such information. And so we get…

False beliefs in medicine (an ironically-apt title, given what follows). The writer tells us that they

attended a lecture recently and heard a highly qualified doctor say we are bound by a number of fallacies around sickness and health. False beliefs. The symptoms are the problem; illness is caused by germs and genes; food has nothing to do with health; drugs can cure us.

As long as we believe these lies we will always look to pharmaceutical companies and medical doctors for the answer to our woes. The real problem is, few people are emotionally mature enough to challenge these false beliefs.

Fluoridating the water is based on one of these. Tooth decay is a symptom of poor diet and toxic overload. So is heart disease, cardiovascular disease, diabetes, cancer, arthritis – every disease process (including polio and swine flu). Nobody wants to believe this because it means they will have to take personal responsibility for their health. I object to being fluoridated/vaccinated/sprayed/medicated because others will not take personal responsibility. Anyone who wants fluoride can get it for themselves – or try eating healthy and brushing their teeth.

Whew! Where to begin?

Well, there is a kernel of truth in some of this – diet does have an impact on health, & it is implicated to a greater or lesser extent in tooth decay, cardiovascular disease, type 2 (not type 1) diabetes, & some cancers. But that’s about where the good bits stop. (Incidentally, if ‘poor diet’ is the cause of all disease, then why do epidemics run their course in the absence of any evidence of widespread dietary change?)

The writer cites “a highly qualified doctor” - this is simply an appeal to authority. No name, so we can’t check out their background or credentials. I’d actually be quite keen to know what the speaker was a doctor of – it would be a rare medical doctor, for example, who’d buy into denialism of germ theory, for instance, as this speaker and our letter-writer appear to do. However, this is not the case for many CAM practitioners (CAM = complementary & alternative medicine).

And including the statement that “illness is caused by germs and germs” on their list of fallacies is a sure sign that we’re hearing from someone who denies the germ theory of disease. Darned if I know where this one comes from. Is it because the writer’s observed that, during an outbreak of infectious disease, not everyone gets sick? It is, however, a logical fallacy to assume that if some don’t get sick, germs can’t be the cause of illness in those who do. Presumably this belief that germs don’t cause disease also underlies the writer’s objection to vaccination – unless they also buy into the many & varied claims regarding the perceived harm done by vaccines…

They certainly miss the point on personal responsibility. Had the polio vaccine been availble to them my mother & my friend Dorothy would have welcomed the opportunity to take responsibility for their own health. This would have been distinctly preferable to many months in an iron lung (Dorothy) & permanently wasted muscles (Mum) – & let’s not forget the savings to the health system. ‘Poor diet & toxic overload’ had nothing to do with their illness.

What is this ‘toxic overload’ thing anyway? It’s a common statement from people who, like our letter writer, are anti- modern medical practice – but they never seem able to pin down just what the toxins are, where they accumulate, or how they do harm. Many of the claimed toxins (including formaldehyde & methanol) are made by our own bodies as a part of normal metabolic processes – in quantities that are generally considerably higher than those supposedly provided by vaccines, drinking diet Coke, and so on. The idea that ‘toxic overload’ is – along with poor diet – the cause of all disease smacks of the thinking exemplified in this 1926 text (but note that nothing therein is in any way evidence-based, & as Harriet Hall notes, our understanding of illness & disease has moved on since then).

Plus – there’s more to personal responsibility than simply looking out for yourself. In the case of infectious diseases – polio included -  infants too young to be vaccinated, and those of all ages who are immunocompromised (cancer patients, for example), rely on herd immunity for their own protection. Denying that doesn’t strike me as a particularly responsible thing to do.

But there’s crank magnetism for you.

the specialities of mad scientists Alison Campbell Sep 26


Oh noes! I am doomed!! It seems (fictional) biologists are almost as likely to be mad scientists as those of the nucular persuasion (click on the graphic for a better-quality image, courtesy of Mad Science):


I should hang out with the chemists more often…

the great tree of life Alison Campbell Sep 24

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This one’s for both teachers & students (& of course, anyone else interested in evolution and evolutionary trees): the Evolutionary Genealogy website :) It’s a site that “seeks to promote the teaching and acceptance of the biological theory of evolution by emphasizing one of its great lessons: that life on Earth is one big extended family, and therefore we are related in an exact way to not only every other living thing, but also to every thing that ever lived.”

(And hat-tip to PZ for pointing me in this direction, and also towards the paper describing how the Time Tree was developed & how it works.)

Evolutionary Genealogy has information on the ‘great tree of life’, and how to use it to look at relationships between any 2 organisms on the tree; the concept of evolutionary genealogy, and a link to the Tree of Life project. (There’s also a shop with some rather wonderful t-shirts – I can’t decide between the border collie & the kitten…)

Related to this is the Time Tree – an on-line calculator that will work out the degrees of seperation/relatedness for you, plus data from both nuclear & mitochondrial DNA, plus links to the sources of the data used in the calculation. Bearing in mind that the dates are perhaps best described as ‘fluid’ – see PZ’s comments thread for an interesting discussion on this), the Time Tree’s looks like it could be a useful teaching tool if one wanted to set an exercise in developing a phylogenetic tree for a group of organisms :) (NB I did this for ‘cat’ & ‘human’ & the ensuing table of molecular timing data has these words at its head: Laurasiatheria/Euarchontoglires. Looks strange (where did my cat & human go?) – until you remember that neither cats nor humans have been around all that long, & the most recent common ancestor would have been a placental mammal that in all likelihood looked nothing like either modern species :)

a cultural divide Alison Campbell Sep 22

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What follows is a re-post of something I originally wrote for my ‘other’ blog over on Talking Teaching.

One of the things that I find profoundly irritating is hearing tertiary teaching staff decrying the efforts of their colleagues in the secondary education system. [Edit: here I must add that it's not something I hear regularly - but I do hear it.] (And yes, sometimes I respond & make myself rather unpopular.) Comments along the lines of “teachers teach [insert topic name here] really badly; the kids come into my classes & they don’t know anything.” Or “secondary teachers do a really bad job of preparing students to study [my subject] at university.” As well as being patronising, these comments are generally just plain wrong, & they reflect a real lack of understanding of the current nature of science teaching in our secondary schools and of the science curriculum itself.

When really pushed, I have asked my colleagues to take a step back & truly reflect on what they’re saying. Do they really think that teachers don’t know anything about the subjects that they’re teaching? Because – what does that say about what’s going on in their own classes? After all, science teachers (in any disciplinary area) will have a science degree – at the very least a BSc, increasingly an MSc, & sometimes the person at the front of the classroom will hold a PhD. And they obtained those qualifications in university lecture theatres and laboratories.

What’s more, our education system has moved on from the ‘old days’ (the days that many lecturers perhaps are harking back to) when most students in 7th form (year 13) classes were going to go on to university. The way it was when I was a secondary student. Then, it could truly be said that students were essentially being primed for university study. But these days, many more students stay on for that final year at school, and they have many more future study options to look forward to. Schools have to support them all in their learning & so it’s simply not realistic to teach a class as if everyone in it was going on to take that subject at uni. It’s far more important to see them gain a thorough understanding of what [insert subject here] is all about AND the skills needed to take their learning to a new level when they move on to another institution, plus the general scientific literacy that’s needed in today’s world.

What of the content? Looking at specifically at biology, it’s huge. I’ve had a number of conversations with teachers & also people in NZQA, about what could & couldn’t be omitted – there is a lot of ‘front-loading’ as new discoveries are made & new techniques developed, but alas! it’s rare that anything falls off the back to compensate. What we need – urgently, in my opinion – is a discussion around just what is ‘core’ knowledge in biology, as that might help to thin things out a bit. So, maybe students don’t need to learn the details of how every latest biotech technique works, but should be able to apply critical thinking skills to issues surrounding the technique’s application?

Such scientific literacy is, of course, the focus of the new curriculum. Have a look at it, & you’ll see ‘the nature of science’ (NOS) at the top of every page. In developing their understanding about science, for example, students will “learn about science as a knowledge system: the features of scientific knowledge and the processes by which it is developed; and learn about the ways in which the work of scientists interacts with society.” They’ll also investigate, ”[carrying] out science investigations using a variety of approaches: classifying and identifying, pattern seeking, exploring, investigating models, fair testing, making things, or developing systems”; they’ll communicate, “[developing] knowledge of the vocabulary, numeric and symbol systems, and conventions of science and use this knowledge to communicate about their own & others’ ideas”; and they’ll participate and contribute, “[bringing] a scientific perspective to decisions and actions as appropriate”. It’s expected that the nature of science will underpin any & all learning activities that students carry out, with the intention that when they leave school they’ll have those skills and that knowledge that I mentioned above.

Related to this is the fact that at the moment the existing NCEA Achievement Standards are being ‘re-aligned’ with the new curriculum. For instance, in many cases particular topics have been shifted around between years eg the genetics material currently in year 13 has been moved, in the curriculum document, to year 12. This means not only that the ASs have to be re-jigged to account for that, but also that the nature of what’s taught has to be re-examined. Year 12 students may not be at the point where they can grasp some of the concepts entailed in the current assessment standards in genetics, for example.

Now of course all this has implications for the universities. From 2014 the students coming through to the tertiary sector from year 13 will have been taught using the new curriculum & assessed using the new set of standards. They will almost certainly have been exposed to less ‘content’ and can be expected to have developed more process skills. (And I don’t envy secondary teachers who must grapple with how to achieve this.) Lecturers assuming that this crop of students will have been taught the same material as all previous intakes will be sadly mistaken. And because of the way they’ve been learning (& how they’ve been assessed) these students may very well have different expectations of how they’ll be learning, & demonstrating that learning, at university.

And these are all things that university lecturers must recognise, and adapt to, if we’re to continue to successfully bridge our students from secondary school and into their tertiary studies.

prized science Alison Campbell Sep 22

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This one’s for anyone with an interest in chemistry – the Prized Science video series, which aims to look at the significance of chemistry in our lives. My colleague Merilyn Manley-Harris alerted me to this site, & the information she sent through to me follows below. So far there’s just the first video of the series up on the site, but it alone is well worth the visit :)

Did life on Mars become life on Earth? What technology worked invisibly behind the headlines to make the Human Genome Project possible? How did wisps of material barely 1/50,000th the width if a human hair become forerunners of a new genre of medicines?

Those topics highlight the premier episode of a ACS new video series, Prized Science:  How the Science Behind ACS Awards Impacts Your Life. It features 2010 Priestley Medalist Richard N. Zare. Rich with high-definition graphics and animations, and commentary suitable for classroom use and other audiences of students and non-scientists, the videos are available without charge at the Prized Science website, YouTube, iTunes and on .  
ACS encourages educators, schools, museums, science centers, news organizations, and others to embed links to Prized Science on their websites. Additional episodes in the series, which focuses on ACS’ 2010 award recipients, will be issued periodically in the months ahead.
’Estimates suggest that more than 30,000 significant prizes – most for scientific or medical research - are awarded annually,’ noted ACS President Joseph S. Francisco, Ph.D. ’For many of them, the spotlight of news media publicity rightly focuses on the recipients. Often lost behind the headlines, is an explanation of how the science honored in the award impacts the everyday lives of people throughout the world. That is Prized Science’s goal, to give greater visibility to the science that won the prize. In doing so, Prized Science strives to give people who may have no special scientific knowledge the opportunity to watch, listen, and discover how the chemistry behind ACS’ awards transforms life.’


science & cooking – quite similar in some ways Alison Campbell Sep 20


Or at least, they are, the way I do things :) 

(Had a busy weekend that included spending much of yesterday out here at work running a Scholarship preparation day for local bio students – hence the lack of posts & my desire to do something light & fluffy today!)

Anyway – many of our dinner guests will vouch for the fact that I’m an experimental cook. In other words, I make stuff up & try it out on them :) But I don’t do it in an uninformed way – otherwise we’d probably have very few people keen for a second visit. In the same way that science builds on the observations, data & theories developed by their predecessors, cooks start with books of recipes and a body of knowledge about what works & think, I wonder what would happen if

In other words, when I was playing around with our new pasta machine (pasta… mmm nom nom nom!) & wondering what to put in the ravioli I was intending to make for dinner (nothing like aiming high from the start), I didn’t start from scratch. I had a fair idea of what ingredients work well together & what might be a total disaster. So the leftover roast chicken could be matched with herbs, plus some ricotta – because I wanted something moist to bind the other ingredients – & parmesan (to give a bit of ‘bite’).

And you learn from your mistakes. The only other time I’ve ever tried my hand at pasta, I didn’t have a clue (no benefit of prior experience that time!) & the recipe I followed wasn’t actually all that helpful. It didn’t mention kneading the dough, for example, nor did it emphasise the need to roll & fold & roll again, multiple times. (It was a bit like a bad science book that assumes the reader knows all that background stuff & leaps right into the details.) If I’d thought about it, my bread-making experience – of which I have lots – would have told me that kneading the dough was going to be essential to ‘work’ the gluten in the flour; ditto the rolling. But alas! I didn’t bring that bit of information across to a new context & as a result that lot of pasta was tough as old boots! As I remember it was takeaways at our place that night.

funny pictures-even kitteh doesn't like  your cooking

This time, having learned by experience, I kneaded my nice eggy dough until it was sensuously smooth & then I used our lovely new toy to roll it & roll it & roll it into silken sheets of pasta. Although – I also know that rather than yield to my Significant Other’s impatience for his dinner I should have used the setting for the very thinnest dough. Because, after all, pasta does expand on cooking & one’s ravioli casing ends up thicker than it otherwise might…

So there’s always room for improvement and refinement – and now & then, for trying something new. (Like those pork-mince cannelloni we had a couple of weeks ago, only instead of pasta tubes I used grilled slices of eggplant – therein lies another recipe!)

more on ‘sweet poison’: aspartame – truth vs fiction Alison Campbell Sep 16

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I’m a regular visitor to Science-Based Medicine. Today there’s a post about aspartame by Steven Novella, which caught my eye given my own interest in this topic. The first paragraph follows below, but I encourage readers to go across to SBM for the full article :)

If you believe everything you read on the internet, then is seems that a chemical found in thousands of products is causing an epidemic of severe neurological and systemic diseases, like multiple sclerosis and lupus. The FDA, the companies that make the product, and the ’medical industrial complex’ all know about the dangers of this chemical but are hiding the truth from the public in order to protect corporate profits and avoid the pesky paper work that would accompany the truth being revealed. The only glimmer of hope is a dedicated band of bloggers and anonymous e-mail chain letter authors who aren’t afraid to speak the truth. Armed with the latest anecdotal evidence, unverified speculation, and scientifically implausible claims, they have been tirelessly ranting about the evils of this chemical for years. Undeterred by the countless published studies manufactured by the food cartel that show this chemical is safe, they continue to protect the public by spreading baseless fear and hysteria.

Read Steven’s complete post on Science-Based Medicine.

retail therapy better than s*x? Alison Campbell Sep 15

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From the UK’s Telegraph (& via the NZ Herald) comes the attention-grabbing headline: ‘Finding a bargain feels as good as sex‘. Well, I’m a fan of a good bargain (mmmm, coats…) so of course I read on.

And was, as usual with such headlines, disappointed.

According to the Telegraph, “Researchers have found that bargains make us so deliriously happy that the brain is turned on to the same level excitement that it gets from sex.” 

We’re told that this was done by measuring activity in various areas of the brains of 50 volunteers while they carried out ‘acitivities including shopping and watching an erotic film.’ (Presumably they were all over 18…) But I’m not so sure that they were actually shopping as the story goes on to say that the university researchers ”used specialist equipment to monitored eye movements and emotional responses in the body to a series of everyday consumer products in 50 volunteers.” It’s hard to check what was actually done as a) the preliminary data were apparently presented in the ‘trade’ journal The Grocer (to which we do not, alas, have an institutional subscription; I must see if the library would rectify that…) & b) there’s nothing about it in the U of Westminster’s own press releases webpage. But let’s see what we can make of it.

It sounds as if the volunteers were fitted with headsets that tracked eye movements; the researchers may also have used electrodes to measure brain activity but that’s not clear from what we have here. Few people would be bold enough to walk down the main street thus outfitted – & the stress associated with doing this would generate anomalous results in any case – your eyes would be all over the place checking on people’s reaction to your ensemble! From the news story it looks more as if they were presented with images of ‘specials’ advertising, or else a series of actual products. And also with naughty films – which apparently generate ‘excitement’ of between 5 & 7 on a 10-point scale. (So – contrary to the initial teaser statement - the volunteers’ response to actual sexual activity wasn’t recorded! Well, that would be a bit trickier to achieve, wouldn’t it?)

A score of 10, we’re told, is associated with major trauma & ‘could be dangerous’.Well, hang on a moment – are the ‘pleasure’ & ‘pain’ regions of the brain the same? If not, then this scale is meaningless as it’s conflating different things. (And there’s some research suggesting that such responses are segregated into different parts of the brain.)

Anyway, back to the chase… Apparently the volunteers recorded a score of 5.8 on viewing a Marmite promotion that included a free offer for a children’s book. A Wallace&Gromit freebie did rather well too. All I can say to that is that if the Marmite/kids’ book combo turned them on so much, they must have had remarkably unexciting personal lives… (And this leads me to wonder about the age distribution of the volunteers – would someone without children get all that excited about this stuff?)

However, as the ‘research’ was commissioned by the Institute of Promotional Marketing, I do suspect a certain amount of bias. They were, after all, interested in finding ways to ensure that shoppers’ eyes focused on clients’ products for at least the few seconds needed to make a decision about buying that product. If ‘specials’ do that, then goody for the retailer, but do we really need to pretend that the ‘excitement’ of finding a bargain at the supermarket equates to the brain arousal associated with activities involving consenting adults?

conspicuous facultative mimicry in octopuses Alison Campbell Sep 14

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Or should that be octopodes? Anyway, this is so much more interesting than so-called psychic octopuses: an octopus whose mimicry can make it more conspicuous, not less.

The ‘mimic’ octopus (Thaumoctopus mimicus – now, there’s a name that Terry Pratchett would appreciate) is arguably the best colour-changer on the block, & it combines its colour-trickery with changes in apparent shape that allow it to be beautifully camouflaged. This sort of cryptic behaviour (aka ‘crypsis’) is well-known in cephalopods, which have very flexible bodies & so can take on a whole range of different postures (aka polyphenism) that may result in them looking nothing like an octopus or squid, at all. Huffard et al. (2010) comment that this sort of shape-changing ability “may impair their predators’ formation and use of a search image.” In other words, the poor old predator can never be quite sure what its potential dinner is going to look like.

What makes T.mimicus unusual is its ability to increase its visibility, which you would expect to be rather counter-productive if done in the presence of predators. It’s not entirely alone in this: the dreaded blue-ringed octopus flashes those irisdescent blue rings as a warning, although you can apparently also see them when the little beast is sitting still. Huffard & her colleagues also list Octopus cyanea, which can copy both the shape & the colour of a parrotfish as it swims above the reef. However, they feel that the best example of what they call ‘conspicuous defence’ is shown by T.mimicus: it’s something called ‘flatfish swimming’, where the animal looks like a flatfish, swims like a flatfish, & is coloured like a flatfish. In other words, not only does it copy flatfish morphology, but their behaviour as well. Even its eyes are placed as you’d see them in a flounder! While the authors identify other ocotopodes that show this behaviour, the mimic octopus is the only one that also uses a conspicuous colouration. The question Huffard et al. set out to answer, is ‘why’? How did this counter-intuitive suite of behavioural traits evolve?


The first thing you’d need to demonstrate is that the behaviour you’re studying is heritable, & not simply the result of learning. It turns out that other studies have recorded flatfish swimming in a naive, lab-reared octopus that had never had the chance to see a flatfish. What’s more, other species of octopus, found in the same habitats as flatfish, don’t show this behaviour. So it’s fair to assume “that the ability to express this behaviour is a genetically determined presence/absence trait” (Huffard et al. 2010), although, given the intelligence of cephalopods, it’s a fair guess that within ‘flatfish swimmers’ some degree of learning may also come into play.  

Another question is – are we looking at an exaptation or an adaptation? ‘Exaptation’ is a term (first coined, I think, by Stephen Jay Gould) used to describe traits that orignally evolved in other circumstances & with a different function, but have since been co-opted for another role. Feathers, for example, probably evolved via natural selection working on animals with slightly better thermoregulatory ability (they’re excellent insulators), but were subsequently co-opted for flight. With adaptations, you’d predict that physical changes & any related behaviour patterns would evolve together.

In the octopus context, Huffard & her colleagues considered several distinct traits related to ‘flatfish swimming’ in T.mimicus: a change from nocturnal to diurnal behaviour; ‘dorsoventrally compressed’ swimming – the bit that mimics the shape of a flounder or other flatfish; high-contrast (& hence high visibility) dark-brown & light coloured body patterns, visible both while swimming & at rest; & mimicing the actual behaviour of flatfish (ie the way they undulate just above the seabed. They predicted that the diurnal behaviour came first, ahead of the swim-like-a-flounder behaviour, & examined a number of related octopode species for the presence/absence of these traits. At the same time, genetic analyses allowed them to build up a phylogenetic tree for Thaumoctopus mimicus & its relatives, which they could then map the various behaviour patterns onto.

From the DNA analyses, the team concluded that the mimic octopus’s closest relative is Wunderpus photogenicus. (No, I’m not making that up! Isn’t it a wonderful name?) W. photogenicus, however, is crepuscular – it’s most active in the dim light of dawn & dusk. Along with several other species, the researchers placed these 2 species in a group they called the ‘Long-Armed Sand Octopus’ clade (or LASO, for short). Mapping various traits onto the family tree that includes LASO, they concluded that both dorsoventrally-compressed swimming and ‘flatfish swimming’ probably evolved in the most recent common ancestor of the LASO group, along with another hallmark of these species: their rather long arms (for which the group is named).

But what would be the selective advantage of simply looking like a non-toxic flatfish? After all, flounders are generally quite palatable, even if you do have to watch out for the bones. One possibility put forward  by Huffard et al. is that some ‘gape predators’ (fish that effectively ‘inhale’ their prey when they open their mouths rapidly) can’t get their mouths around an adult flounder. They also suggest that swimming with a dorsoventrally flattened body may be a more energetically-efficient manner of moving around if you’re an octopus with disproportionately long, skinny arms, although there’s no data provided on this one.

On the issue of visually-conspicuous colour patterns, in the LASO clade these seem to be restricted to the mimic octopus and its wonderful photogenic relative (sorry, I mean W.photogenicus; I just couldn’t resist!). While other species use some startling colour patterns in defense (basically bluffing that they’re nastier or more toxic than is really the case), only mimicusphotogenicus have the same colour pattern when they’re resting. The team suggest a couple of possibilities here: the colours may act as disruptive colouration, a form of camouflage that makes it harder to see the actual body outline of the animal. Or they may have been selected for because wavy stripey arms somewhat resemble highly toxic sea snakes.

While these may read like ‘just-so stories’, the team do offer ways of testing them. They suggest examining the highly visible pale/white component of the animal’s colouration to see how well it matches the seabed of their normal habitat, which is black sand with white shell fragments on it. It should also be possible to test mimicus for toxic or unpalatable chemicals – it really could be nasty to eat, in which case the colour patterns take on a whole new role, that of warning predators to avoid it altogether.

Now, none of this mimicry is perfect – after all, to a human observer the ‘lionfish’ copycat isn’t all that close, and even the ‘swim-like-a-fish’ appearance and behaviour is flawed. But to expect perfection would be to fall into the trap of thinking that a perfect result is the normal outcome of natural selection. It isn’t. The existing behaviours might be just enough to give a hungry predator pause as it eyes up its dinner, and ‘[these] decisions may cause enough confusion to allow ‘mimic’ octopuses to escape predation’ (Huffard et al. 2010) & live to copy flounders another day.

CL Huffard, N Saarman, H Hamilton & WB Simison (2010). The evolution of conspicuous facultative mimicry in octopuses: an example of secondary adaptation? Biological Journal of the Linnaean Society, 101, 68-77

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