SciBlogs

Archive 2013

just like ‘alien’ – moray eels have *two* sets of jaws Alison Campbell Dec 19

No Comments

Around 14 months ago the husband & I were spending a lazy holiday in Rarotonga. We did quite a bit of snorkelling on the reefs, and especially enjoyed our experiences at Muri, where we saw a good range of reef fish in near-ideal conditions (as in, clear, calm, relatively shallow water). There were several moray eels, which were at first hard to spot – and then you saw them, loitering in a crevice, giving the impression of watching you rather closely and with their open mouths exposing some rather sharp, pointy teeth: “all the better to bite you with, my dears.” We viewed them with caution.

But when you think about it, that wide-mouthed loitering would seem to pose a problem for the eels. This is because most predatory fish feed by opening their mouths wide from a closed position: water floods into the lower-pressure area inside the mouth & dinner comes along for the ride. Sitting around with your mouth half-open doesn’t sound like a good strategy. I found the answer while reading The Book of Barely Imagined Beings by Caspar Henderson, under – you’ve guessed it – ‘E for Eel’. (This wonderful book was recently reviewed on Sciblogs by Siouxsie Wiles.)

 

As an aside, I love the way this chapter kicks off:

The Snowflake1 eel, a kind of moray, is harmless if you leave it alone and refrain from drinking its blood (which is toxic).

I was also fascinated to know that the morays’ genus, Echidna, derives from a rather unpleasant individual in Greek mythology; beside her, Henderson says, “the Snowflake and other Moray eels are pussycats” – yet people still fear them:

Part of the reason for this is surely their superficial resemblance to snakes… Another may be the eels’ mouths, which are constantly open, suggesting that they are ready to strike. But this is not, I think, the whole story. An eel’s eyes, bulging and unblinking, look like those of a corpse, and the way the animal moves its body … is disturbingly sensual. Saltwater eels are uncanny.

You can see, I hope, why I like the book; the writing is lovely. But anyway, back to those gaping maws.

Henderson explains how a moray’s hunting style more closely resembles the eponymous ‘Alien’, for these eels have two sets of jaws! The second set is found in the back of the throat – the ‘pharyngeal jaws’ -  but can be thrust forward extremely quickly and retracted equally rapidly, so that they “[pull] the prey down into the oesophagus as the animal closes its mouth.” You can see how this all works in the image below, from the National Science Foundation website.

Image credit: Zina Deretsky, National Science Foundation (after Rita Mehta, UC Davis)

The work of Rita Mehta, who’s been studying moray eels’ feeding anatomy, is featured in the following video, in which you can see those pharyngeal jaws move forward to grasp a ‘prey’ item. All the more reason to be fairly circumspect on the reef, methinks!

1 If you think ‘Snowflake’ is an unusual name for an eel, how about the ‘Rusty spaghetti’ version?

kiwi evolution – a new take on an icon’s ancient past Alison Campbell Dec 18

3 Comments

‘The’ kiwi (Apteryx spp.) has always been a bit of an enigma, not least for the fact that it lays an absolutely enormous egg in comparison to its body size. In one of the essays in his book Bully for Brontosaurus (1991), Stephen Jay Gould argued that this differential in egg/body size was due to the impact of scaling: kiwi, he believed, had ‘downsized’ from a moa-like ancestor but had retained the large moa-type egg. This idea was quite widely accepted, even though later genetic evidence indicated that kiwi were in fact more closely related to the Australian emu than to NZ’s now-extinct moa. But new research suggests quite a different evolutionary trajectory – and I rather suspect that Gould, great scientist that he was, would be delighted to see his hypothesis robustly challenged :)

The research reported in this news article from scoop.co.nz will be published in the Proceedings of the 8th International meeting of the Society of Avian Palaeontology and Evolution – you’ll find the abstracts of the conference papers here. A newly-described fossil, from what’s known as the ‘St Bathans fauna’ of Central Otago turns out to be a new genus and species of kiwi, but a tiny one by today’s standards. Paul Scofield, one of the paper’s authors, is quoted in the scoop report as saying that

[this] fossil from the early Miocene, about 20 million years ago, shows us that it’s a tiny bird about one third the size of a small kiwi today. It suggests the opposite [to Gould's hypothesis] is, in fact, the case – that the kiwi has developed towards a larger size, a trend that is seen in many birds from the early Miocene.

So, how would an ancestral kiwi have arrived in New Zealand? The suggestion is that they flew. This is based on the evidence that a) kiwi and emu are more closely related than kiwi and moa and b) the emu-ish early kiwi arrived here after NZ and Australia were separated by the developing Tasman Sea.

Finding the wing bones of this new fossil species would help to confirm/deny this proposal. Although – having read the abstracts for the conference, I can’t help wondering if a proxy might be the size of a part of the brain known as the ‘cerebellar flocculus’, as suggested in another presentation by Walsh et al. It’s an intriguing possibility, anyway! And I’m wondering – how may we then explain that anomalous kiwi egg?

I’ll look forward to getting hold of a copy of the paper by Worthy and his colleagues, once it’s published.

 

Gould, S.J., (1991) Of kiwi eggs and the Liberty Bell, pp 109-123 in Bully for Brontosaurus. Penguin Books, London. 

Walsh, S., Iwaniuk, A., Knoll, M., Bourdon, E., Barrett, P., Milner, A., Abel, R., & Dello Sterpaio, P. (2012) Can the size of the avian cerebellar flocculus be used as a proxy of flying ability in extinct birds? 8th Internat. SAPE Meeting, 11.-16. June 2012 Naturhistorisches Museum Wien

Worthy, T.H., Tennyson, A.J.D., Salisbury, S., Hand, S.J., & Scofield, R.P. (2012) A fossil kiwi (Apterygiformes) from the early Miocene St Bathans fauna, New Zealand. 8th Internat. SAPE Meeting, 11.-16. June 2012 Naturhistorisches Museum Wien

secrets from an ancient graveyard Alison Campbell Dec 16

No Comments

One of my current favourite TV programs is Time Team – I enjoy learning little bits of history & Tony Robinson’s happy enthusiasm is so contagious (but I still think of him as Baldrick). So you’ll understand that I was happily distracted this morning when, while looking for something else (isn’t that usually the way?), I stumbled across a fascinating piece about an ancient graveyard in the Italian town of Badia Pozzeveri.

Published on Science magazine’s site, the article tells the story of the ongoing excavation of a medieval graveyard. The dig is providing a wealth of information on things like the dietary differences between nobles, monks, & peasantry (based on isotope analysis of their teeth) & the impact this had on health. What’s more, using ancient DNA (aDNA) techniques, the scientists leading the dig are hoping to identify the presence of various pathogens, such as Yersinia pestis (the bacterium linked to the Black Death, and which still causes cases of plague in the US today) and Treponema pallidum, which causes syphillis and has already been found in 16th-century mummies from Naples.

And like many episodes of Time Team, the tale has a twist at the end: a bit of fashion-based detective work showed that at least some of the burials were not medieval at all.

selecting for maladaptive behaviour Alison Campbell Dec 13

2 Comments

One of the questions that often comes up in my first-year bio classes relates to natural selection and human evolution. Does the fact that modern medical science keeps alive people who in previous centuries might have died, mean that we’re countering the effects of natural selection? As you can imagine, this generates quite a lot of interesting discussion that spans ethical issues as well as the obvious biological ones.

Next year I think I’ll give the class a new paper to read: one that examines such a question in the context of the Chatham Island black robins (Petroica traversi) (Massaro et al, 2013).

As many New Zealand biology students may know, by 1980 the breeding population of this little bird was reduced to a single pair, in a total population of seven. Things were not looking good, but dedicated conservation workers – led by the late Don Merton (there’s a lovely obituary for him here) – managed to turn things around by careful management of the population, including fostering the robin’s first clutches under another species (thus inducing the robins to lay again), and translocating the small population from Little Mangere Island to the better habitat on Mangere Island. However, it seems that at the same time, the conservationists were also unwittingly selecting for a distinctly maladaptive behaviour – that of laying eggs that were left teetering on the very brim of the nest.

After that initial bottleneck event the population slowly started to recover. However, the researchers working with them noticed that in 1984 one of the five breeding females laid a sinlge egg were laid at the edge of her nest, with more females following suit in subsequent years. Left alone the eggs didn’t hatch, mainly because they weren’t incubated (although I suspect some could simply fall off the edge). The obvious thing to do was to reposition the eggs in the nest, & this resulted in an increased in chicks hatched & subsequently fledged. However, Massaro & her colleagues report that by 1989 18 of the 35 females (51%) were ‘edge-layers’, a behaviour that would leave the population completely reliant on human intervention if edge-laying continued to spread.

The research team suspected that this was an example of inherited rather than learned behaviour, and hypothesised that

[if] rim-laying [had] a genetic basis, and its spread [had] been facilitated by human intervention through egg repositioning, the frequency of this trait would be predicted to decrease following cessation of intervention.
Conservation workers stopped moving rim eggs in 1990, which then meant that the researchers could subsequently compare data sets:
we therefore compared egg-laying data from three years before cessation of repositioning (1987–89) with a three year period almost two decades after management stopped (2007–09)

and found that the number of rim eggs being laid decreased significantly between those two periods. They next looked at the many years’ worth of data to see if the ‘rim-laying’ behaviour had any effect on individuals’ evolutionary fitness, and discovered that

[when] rim eggs were not repositioned, females that laid rim eggs had significantly reduced clutch sizes (i.e. number of eggs laid inside nests that were incubated), and decreased hatching and breeding success compared to normal-laying females, demonstrating that rim laying substantially reduces fitness.
The final step was to confirm that this maladaptive behaviour did have a genetic underpinning. This part of the study was aided by the fact that there’s an extensive genetic pedigree available for this closely-studied species. Examining that pedigree, Massaro & her co-workers found that a) the behaviour first showed up in the grand-daughters of the ‘founding’ female, ‘Old Blue’; and b) that the population was highly inbred. A detailed analysis of the pedigree led them to determine that the rim-laying trait was an autosomal dominant trait that’s inherited in a Mendelian manner (ie no evidence of sex-linkage). Their final message:
This episode yields an important lesson for conservation biology: fixation of maladaptive traits could render small threatened populations completely dependent on humans for reproduction, irreversibly compromising the long term viability of populations humanity seeks to conserve.

 

You’ll also find information on the study here on the University of Canterbury website.

Massaro M., Sainudiin, R., Merton, D., Briskie JV, Poole, AM, Hale ML (2013) Human-Assisted Spread of a Maladaptive Behavior in a Critically Endangered Bird. PLoS ONE 8(12): e79066. doi: 10.1371/journal.pone.0079066

 

shaking up the academy? or, how the academy could shake up teaching Alison Campbell Dec 10

No Comments

This is something I originally wrote for my ‘other’ blog over at Talking Teaching.

Last week I spent a couple of days down in Wellington, attending the annual symposium for the Ako Aotearoa Academy. The Academy’s made up of the winners of the national Tertiary Teaching Excellence Awards, so there are around 150 or so of us now. While only 35 members were able to make it to this year’s event (& the executive committee will survey everyone to see if there’s a better time – having said that, everyone seems so busy that there’s probably no date that would suit everyone!), we had a great line-up of speakers & everyone left feeling inspired & energised. I’ll blog about several of those presentations, but thought I would start with one by Peter Coolbear, who’s the director of our parent body, Ako Aotearoa.

Peter began by pointing out that the Academy is potentially very influential – after all, it’s made up of tertiary teachers recognised at the national level for the quality of their teaching, & who foster excellence in learning & teaching at their own institutions.  But he argued – & I agree with him - that there is room for us to become involved in the wider scene. Peter had a number of suggestions for us to consider.

First up, there’s a lot going on in the area of policy – are there areas where the Academy might be expected to have & express an opinion? For example

  • There’s the latest draft of the Tertiary Education Strategy (TES), which ”sets out the Government’s long-term strategic direction for tertiary education; and its current and medium-term priorities for tertiary education.” There’s a link to the Minister’s speech announcing the launch of the draft strategy here.
  • In addition, the State Services Commission’s document Better Public Services: results for New Zealanders sets out 10 targets across 5 areas. Targets 5 & 6 are relevant here as they are a reference point for government officials looking at evidence for success in the education sector. (Such scrutiny is likely to become more intense in light of the 2012 PISA results, which have just been made public.) Target 5 expects that we’ll “[increase] the proportion of 18-year-olds with NCEA level 2 or equivalent qualification”; #6 is looking for an increase in “ the proportion of 25 to 34-year-olds with advanced trade qualifications, diplomas and degrees (at level 4 or above)”. This will increase the pressure on institutions to increase retention & completion rates – might this have an effect on standards?
  • There’s also the requirement to achieve parity of success for ‘priority’ learners, especially Maori & Pasifika – this is priority #3 in the TES. (Kelly Pender, from Bay of Plenty Polytech, gave an inspirational presentation on how he weaves kaupapa Maori into pretty much everything he does in his classroom, in an earlier session.) And it’s an important one for us to consider. Peter cited data from the Ministry of Education’s website, ‘Education Counts’, which showed significantly lower completion rates for Maori & Pasifika students in their first degrees compared to European students, and commented that this will likely become a major issue for the universities in the near future.
  • If we’re to meet those achievement requirements, then how institutions scaffold learners into higher-level study, through foundation & transition programs, will become increasingly important. What are the best ways to achieve this?
  • Peter predicted increased accountability for the university sector (including governance reform). Cycle 5 of NZ’s Academic Audits has begun, and ”is to be framed around academic activities related to teaching and learning and student support.” This is definitely one I’d expect Academy members to have an opinion on!
  • He also expects strengthened quality assurance processes throughout the education sector: this suggests a stronger (& more consistent) role for the  NZ Qualifications Authority, with the development of partnership dialogues across the sector (ie including universities).

Then, at the level of the providers (ie the educational institutions themselves – & that’s not just the polytechs & universities), we have:

  • a targeted review of qualifications offered at pre-degree level – there’s background information here;
  • a government-led drive to get more learners into the ’STEM’ subjects (science, technology, engineering, & maths) – this poses some interesting challenges as at university level we’re seeing quite a few students who’ve not taken the right mix of subjects, at the right NCEA level, to go directly into some of the STEM papers they need for, say, an engineering degree;
  • the rise in Massive Open On-line Courses, or MOOCs. (I find these quite strange creatures as they are free to the student and typically attract very large enrolments, but also apparently have very low completion rates. What’s in them for the institution? A good way of offering ‘taster’ courses that hook students in?)
  • the likelihood that we will see the development of a system for professional accreditation of tertiary teachers (I’ve written about this previously and will write another post fairly soon, as accreditation was the subject of a thought-provoking session at the symposium);
  • how we achieve protection of academic standards – it’s possible that government policies (eg those linking funding to completion & retention rates)may result in a tendency to exclude of underprepared kids &/or lowering standards – neither is desirable but both are possible results of those policies.

That’s a big list and the Academy can’t do everything! So, what should it focus on? (This is not a rhetorical question – it would be great to get some discussion going.) The Academy, in the person of its members, is effectively a resource; a body of expertise – can it become a ‘go-to’ body for advice? Speaking personally I think we need to make that shift; otherwise we remain invisible outside our individual institutions & the teaching-focused activities we’re involved in, & in a politicised world that’s not a comfortable thing to be. Can we, for example, better promote the significance of teaching excellence outside the education sector? Become involved in the discussions around & development of any accreditation scheme? Develop position papers around maintaining teaching excellence in the context of the new TES?

What do you think? And what shall we, collectively, do about it? 

nz’s pisa rankings slip, & the soul-searching begins Alison Campbell Dec 05

No Comments

The latest PISA results are out, and NZ – despite remaining in the ‘above the average’ group for OECD countries – has nonetheless  slipped in this measure of achievement in reading, maths administered by the Programme for International Student Assessment . This is of concern, & there are probably multiple complex causes for our decline. Certainly the previous PISA commentary (2009) recommended that we pay attention to matters of inequality (There’s interesting commentary here, & also on the RNZ website.)

This morning’s Dominion-Post (I’m in Wellington at the moment, at a teaching symposium) carries a story giving a primary-teaching perspective.There are two key issues here: many primary teachers lack a science or maths background; and primary teachers in general are not well supported to teach these specialist sujects. (The removal of specialist science advisors - something I’ve commented on previously - did not help things.) This is important, because if students don’t gain a good understanding of these subjects – and good experiences of them! – during primary school, then they’ll basically be playing catch-up when they arrive in specialist secondary school classrooms.  Sir Peter Gluckman’s suggestion (in his report Looking ahead: science education in the 21st century) that each primary school have a ‘science champion’ would help here, but in the medium-to-long term it would probably be even better if intending primary school teachers received much greater exposure to the STEM subjects to begin with.

Should we worry? Yes, but I definitely agree with Fiona Ell, from the University of Auckland, who’s quoted in this morning’s Herald as saying:

People get very hung up on the ranking … because it’s like a Top of the Pops top 10 thing. I don’t think they should be ignored … but knee-jerk reactions to rankings are really dangerous in education systems.

So, there are issues that we need to address, and as Fiona’s pointed out, there are no quick fixes – we need to deal with them in a considered way that includes as many variables as possible (i.e. not just practices in schools).

One of those issues is highlighted by Sir Peter Gluckman, the Prime Minister’s Science Adviser, who’s said:

What’s worrying is that there seems to have been a decline in the people represented in the top end of the scale and an increase in the number of people at the bottom end of the scale.

And socioeconomic status may well play a part in this. From the Herald story:

New Zealand was one of just two countries in which socio-economic status had a strong connection to a student’s performance. Some countries’ education systems made up for social disadvantage, but this was not the case in New Zealand.

So any solution addressing the PISA results will of necessity be complex. It’s not going to be sufficient to look only at what’s going on in schools. Yes, support and professional development for STEM teaching across the compulsory sector will be needed. The quality of teaching is definitely important (for a student’s perspective see the Herald article). But without also seriously considering and attempting to deal with the social inequalities in this country, I suspect changes in the educational sector alone will not be enough.

 

the daily mail comes late to the pig-ape hybridisation idea Alison Campbell Dec 02

No Comments

In posting an item about the ‘pig-ape hybridisation’ suggestion for human origins, the Daily Mail is a) coming rather late to the story (a slow day in the newsroom, perhaps?) and b) showing more regard for sensationalism than for good investigative journalism.

The story’s one I’ve posted about before (& I’ve reposted my original piece below). Seeing it again really makes me think that the originator of this particular idea is trying to have it both ways. If our morphology is as similar as he claims to that of pigs, and different from chimps, then the differences should show up in our genes. Yet they don’t; genetically we are much closer to chimps than to swine. He claims that this can be explained by repeated back-crossing with early humans – which is effectively no more than special pleading (& conveniently ignores the issue of significant differences in chromosome number between the two taxa). 

 

The internet is a wondrous place: a source of information, of amusement, and – alarmingly often – of material that elicits a combination of ‘say what?’ and <head-desk>. And a hat-tip to PZ Myers for this particular example…

For it has been proposed (by the originator of this particular hypothesis, & further discussed on phys.org) that humans arose as the result of an interspecies hybridisation event, rather than the current model for human evolution that sees chimps and humans sharing a Last Common Ancestor 5-6 million years ago and following their own trajectories since that time.

The event? Hybridisation between great ape (specifically, chimpanzee) & wild boar.

?

?

?

Now, we know that hybridisation happens; that the ‘biological species concept’ is not an absolute. But these events are generally between reasonably-closely related species: hybridisation is quite common in the waterfowl, for example. But even in birds, where hybridisation is well-documented, it doesn’t appear to cross the lines between one taxonomic order and another. Yet the ‘pig+ape’ suggestion requires hybridisation between different taxonomic orders – orders that (so fossil & genetic evidence tell us) have been separate for between 79 & 87 million years.

Surprisingly, Dr McCarthy, a geneticist and the proponent of this novel hypothesis, doesn’t present much in the way of genetic data to support it. He does agree that, genetically, we are closer to chimpanzees than to any other mammal, but suggests that this is due to back-crossing (with the chimp parent) after the initial hybridisation event:

And why might one suppose that humans are backcross hybrids of the sort just described? Well, the most obvious reason is that humans are highly similar to chimpanzees at the genetic level, closer than they are to any other animal. If we were descended from F1 hybrids without any backcrossing we would be about halfway, genetically speaking, between chimpanzees and whatever organism was the other parent. But we’re not. Genetically, we’re close to chimpanzees, and yet we have many physical traits that distinguish us from chimpanzees.

Surely the simpler explanation – that we are genetically similar to chimps because we are sister species – is more likely. Especially since at least some of the differences between the two species can be explained by differences in timing of developmental stages (the relative proportions of face & skull, for example), which may be sheeted home to mutations in regulatory portions of the genome.

In addition, there are major differences both in chromosome number (38 in pigs, 46 in humans) and in the position of various genes on those chromosomes that would make successful gamete production in any hybrid unlikely in the extreme (always supposing the hybrid was actually viable) - PZ discusses this in more length.

But anyway, what about those physical traits that “distinguish us from chimpanzees” & supposedly reflect our shared heritage with pigs? There’s a long list here. Many of them relate to bipedalism; to me, it’s special pleading to suggest that (for example) the presence of large gluteal muscles in bipedal humans and in domestic pigs is evidence of a close evolutionary relationship (Animal Farm aside, there is a distinct lack of evidence for bipedal locomotion in suids – and strong evidence of selective breeding for large backsides in pigs destined to become bacon & pork). Hairlessness? Only in domestic pigs; anyone who’s watched a huntin’&fishin’ show on TV will have seen how hairy a wild boar is. Pigs & humans both have longer hind-limbs than forelimbs, & shorter digits (compared to chimps)? Well, ye-es, I guess so, but that’s hardly evidence for a close relationship; one could say the same of mice… Similarly, while humans & pigs may (usually) be particular about where they defecate, well, so are other animals; rabbits, anyone? As for “snuggling [snuggling???], tears, alcoholism “being shared features in humans & pigs but not chimps… chimps & humans both have an enzyme (alcohol dehydrogenase 4) that allows us to break down ethanol, and it seems that chimps can become addicted to alcohol if given the opportunity.

Also offered in evidence are those diseases which are rare in non-human primates: “heart attack, atherosclerosis, and cancer (melanoma)”. Since these are to some degree, age-related, their relative rarity (for they are not absent in apes) may be ascribed to differences in lifespan: chimps in the wild may not live long enough to develop them.

Annoyingly, I see that over at uncommondescent, this proposal has been presented as even more evidence that evolutionary biologists are Getting It Wrong!

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Perusing more of the macroevolution website, I found the suggestion that armadillos and pangolins evolved from ankylosaurs and stegosaurs (page 244 at that link). It would be interesting to hear a palaeontologist’s taken on that one, but the fact that dinosaurs had diapsid skulls while mammals are synapsid doesn’t help.

the fascinating psychology behind conspiracy theories Alison Campbell Nov 21

8 Comments

I’ve just read (via the NZ Skeptics page on FB) a fascinating article on Slate about the psychology of conspiracy theorists. In it, Will Saletan describes a series of studies from the past 20 years, that attempted to understand why a fair proportion of people seem to incline towards conspiracy theories (for example, a 2007 poll found that only 64% of adults in the US believed that the 9/11 attacks caught their government off-guard: most of the remainder believed that the powers-that-be either knew in advance or were actually actively involved).

The experimental data Saletan discusses seem to show that the distrust (or at the very least, cynicism) that many participants demonstrated is based on how those participants perceived the character of others:

… it’s a common weakness known as the fundamental attribution error – ascribing others’ behaviour to personality traits and objectives, forgetting the importance of situational factors and chance. Suspicion, imagination, and fantasy are closely related.

He goes on to say that

The more you see the world this way – full of malice and planning instead of circumstance and coincidence – the more likely you are to accept conspiracy theories of all kinds. Once you buy into the first theory, with its premises of coordination, efficacy, and secrecy, the next seems that much more plausible

and presents additional data to support that contention. (Orac has also written about this from time to time.)

I have to say, some of the anti-fluoride commenters we get on Making Sense of Fluoride certainly appear to fall into the fundamental attribution error. How else can one interpret the assumptions that fluoridation is the result of one big (global) conspiracy theory (linked, in the minds of at least some commenters, with a nebulous depopulation program), and that those discussing the science in favour of fluoridation are naturally being paid to do so.

And given that at least some groups who oppose water fluoridation (with statements such as “The problem is that the research and information is used to educate medical practitioners is completely false, they have literally been brainwashed when it comes to fluoride”) also oppose vaccination (with talk of hoaxes), then I have to agree with Saletan that

Conspiracy believers are the ultimate motivated skeptics. Their curse is that they apply this selective scrutiny not to the left or right, but to the mainstream. They tell themselves that they’re the ones who see the lies, and the rest of us are sheep. But believing that everybody’s lying is just another kind of gullibility.

 

why did the pigeon cross the road? Alison Campbell Nov 19

No Comments

if I lived in Hawkes Bay I’d be keen to attend this Royal Society public lecture, & I’ll certainly be watching the video, which will be available after. It looks like being of interest & value to senior Biology teachers.

The ninth lecture in the 10X10 series

Why did the pigeon cross the road?

Dr Claire Postlethwaite

Napier | 7.30 Tuesday 19 November | Hawke’s Bay Holt Planetarium | View Livestream

In this lecture, Dr Claire Postlethwaite  (University of Auckland) will talk about using mathematical models to understand animal behaviour, using examples from homing pigeons,  possums, bees and electric fish.

The lecture is being livestreamed courtesy of i-film NZ Science. You can watch the lecture live or watch it afterwards. You can also skip back and see earlier parts of the talk while it is livestreaming. 

Visit our website for full details of the 10X10 Lecture Series, including audio and video recordings of previous speakers in the series.
View Livestream

 

The lecture is free and open to the general public. Enquiries: 04 472 7421 or 

 

a glorious (but deadly) cephalopod Alison Campbell Nov 18

No Comments

Every now & then the husband goes on a fossil-fossicking expedition, in order to add to his collection of things long dead & turned to stone. There are a number of good sites in the Waikato region, and one of them has yielded quite a few belemnite remains: specifically, the bullet-shaped fossilised internal shells of one group of cephalopods. Plus he’s also found a few rather lovely ammonites, though nothing on the same scale as a giant specimen found near Kawhia Harbour in 1977. (Apparently the largest of all was found in Germany – its shell, if uncoiled, would be close to 11m long!).

The evolutionary history of cephalopods spans around 500 million years, and there’s a good overview of this on the UCMP(Berkeley) evolution website. I hadn’t visited this part of their site before, but was directed there by PZ Myers (who else?) & his use of this stunning image – too beautiful not to share :)

Beautiful, but deadly:

These little molluscs – members of the largest species grow to be about 15 cm long, head tip to tentacle tip – produce two different venoms. One, they use in hunting their usual prey1 of crabs and shrimps; the other is released when the animals are alarmed or agitated. While people certainly report blue-ringed octopus bites, it seems that the toxin may also be secreted directly into the water: the author of this website reports feeling localised neurological symptoms after putting his hand into a tank of seawater that had been used to transport a largish specimen. The venom contains the poison tetrodotoxin (TTH)2, also produced by a range of other organisms including a genus of newts, some harlequin frogs, snails, and worms from a number of different phyla. And, of course, the pufferfish, whose family name (Tetraodontidae) gives us the name of the toxin.

This poses an interesting question: why would members of so many different phyla evolve the same poison? It turns out that it’s not actually the animals who make the TTH: the job’s done by colonies of symbiotic bacteria living in their poison glands. Life really is more complex and more complicated than we can imagine.

1  Sometimes, the prey fights back:

2 It’s been suggested that TTH is the mysterious ingredient supposedly used in zombifying people – you’ll find an interesting discussion of this idea here on HowStuffWorks.

Network-wide options by YD - Freelance Wordpress Developer