Posts Tagged sci-blogs

Illustrating Carl Zimmer’s Readers David Winter Mar 18

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Carl Zimmer has been wondering what to do next. Obviously, he’s going to keep writing his wonderful science stories and continue to maintain the Science Tattoo Emporium but where to do that , and how to make money from it, is less clear. Carl’s a scientific kind of guy, so he wanted get some data to inform his decision. The results of his reader’s survey are out and they’re interesting. But, for all Carl’s skill with words data wants to be pretty, so here are a couple of the the key conclusions of his reader’s survey illustrated with the help of ggplot.

Where do readers of The Loom get their science news?

How much would they pay for an e-book from a scince writer they liked?

Lawrence Krauss on a bad day David Winter Mar 17

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Dunedin got to see Lawrence Krauss on a good day and a bad day this week, but that’s not to say one of his presentations was better than the other. Yesterday the award winning physicist and scientific communicator revealed to his audience that his outlook on life changes from day to day. On good days he can revel in the wonder of a universe that could come to know itself due to a series of accidents that started 10-31 seconds after the big bang and allowed the creation of first matter then atoms, stars and planets and finally astronomers. On bad days he despairs at the lack of scientific thinking in journalism and politics and thinks these problems, and the anti-scientific forces that fuel them, will probably prevent us from doing anything meaningful about climate change.

Krauss’ awe inspiring story of an atom’s journey from the birth of the universe to its death will gain nothing from my retelling it. If you weren’t able to see it then you’l be glad to know his talk was a précis of his excellent book ATOM: An Odyssey from the Big Bang to Life on Earth…and Beyond and covers similar ground to this recored lecture. Perhaps I’m a masochist and a pessimist, but I’m going to skip the awe inspiring story to focus on what Lawrence Krauss thinks about on a bad day. His talk on “Science, Non-Science and Nonsense” described the sources of scientific confusion in society and the tactics used by those groups that seek to take advantage of it.

Krauss argued that the goal of science education and science communication should be to make sure everyone develops a functioning bullshit filter. He didn’t express his thesis quite as bluntly as that, but his core idea is that spreading a scientific mindset would allow us to short circuit needless debates (is global warming real?) and let us get on to the important ones (what are we going to do about it?). He used a neat example to illustrate how this sort of scientific common sense could stop nutty ideas before they get started. UFO enthusiasts often cite the ability of the lights they observe to perform right angle turns at speed as evidence of their otherworldliness. In fact, Krauss pointed out, common sense should tell us that these apparently amazing maneuvers are evidence that the lights in question are not being emitted by a massive object moving through the sky. The only way to turn at a right angle is to stop then change direction, for a UFO to do all its slowing down and stopping so quickly a human observer couldn’t perceive it would generate G-forces with a strength about 2000 times greater than earth’s gravity. And quite a mess.

If the evidence used by UFO junkies is so silly then why do continue prosper? Why aren’t people already filtering this sort of nonsense? The standard of scientific reporting in the media certainly has a lot to answer for. Krauss cited the normal concerns, a fractionated media market means viewers can choose a source of news that confirms their biases and the innate need of journalists to present balance is misplaced in science stories when, in almost every case, one side is wrong and we usually know which side that is. He also mentioned something I hadn’t thought about before. According to Krauss, part of the problem with science coverage in mainstream reporting is that journalists don’t feel qualified to make scientific pronouncements. Writers and broadcasters are happy to make bold statements on politics, financial markets and sports but will shy away from even a scientifically uncontroversial statement like “evolution is a fact.”

Scientific understanding might not be helped by meek journalists and the false equality of balance but most journalists aren’t setting out to deliberately mislead the public on science. Unfortunately, there are forces at work that are doing just that. Krauss had a tonne of examples from the culture wars in his native USA to draw on but he also took the time reminded us of our home grown cranks, citing the New Zealand Climate “Science” Coalition and Ray Comfort (The Apologist’s Nightmare ) as evidence we aren’t immune to anti-science in New Zealand. As you’d expect Krauss exposed just how vacuous the claims of intelligent design creationism and the objections of climate change denialists are, but he also attempted to deconstruct the PR strategies each group use. Both campaigns seek to take advantage of the public’s sense of fairness and journalists’ willingness to provide balance to any point of view. The Discovery Institute would have you believe their goal is simply to get their science a fair hearing in the classroom. But they don’t have a science. For normal science, theories only make it into the school curriculum after they’ve been proposed, tested, retested and confirmed. The ID crowd don’t want fair treatment, they want special treatment, to avoid that boring scientific process and start in the classroom!

Krauss could hardly have known this, but our own climate cranks play the same game. I hate to make an example of this article because the author usually covers science well, nevertheless it highlights the point. In an effort to provide balance to a story on how the IPCC might be made better the author contacted Vincent Gray for comment, here’s the paragraph

Wellington scientist and climate change sceptic Vincent Gray said the researchers were continually coming up with “new models” but they were still “fiddling the figures” and were unlikely to restore public confidence in their work until their projections were proven

That sounds pretty fair doesn’t it? Climate scientists can run their model forward in time and if their projections match observations we’ll take action. Actually, it’s absurd. As Krauss emphasised in his talk, the evidence for climate change doesn’t only come from models, we have tonnes of data that tell us the earth is warming and the seas are rising. Combine those data with the fact recent temperature records are within the uncertainties of the IPCC’s projections and sea levels are near to the upper bound of those projections and Gray’s sound bite seem less fair.

Krauss had more problems than solutions in his hour long presentation. In fact, it’s a testament to the passion he has for his science and skill he has as a scientific communicator that he managed make a talk made almost entirely of depressing facts seem invigorating. The only ray of hope Krauss offered us was that when people’s backs are to the wall they abandon their their preconceptions and to turn to science. In 2003 George W. Bush said that he believed “both sides” of the “evolution debate” should be taught in schools. In 2005 Bush was faced with the prospect of Avian flu becoming able infect humans. Confronted with threat of a flu pandemic the Bush administration dispensed with its evolutionary agnosticism and planned for the possibility of genetic mutations allowing viruses to pass from human to human. That sort of infectivity requires conformational changes in surface proteins which create a new function, exactly the sort of phenomenon the ID crowd think is so improbable as to be effectively impossible.

Krauss will be presenting something very similar to his Dunedin talk in Auckland next week. I’d encourage anyone who has the chance to get out and seem him, he’s a very chrasmatic and interesting speaker. You might even ask the question I really wish I did now- how are we going to fix all these problems?

Sunday Spinelessness – Extreme Close-up David Winter Mar 14

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Almost all the photos I’ve used to illustrate these Sunday Spinelessness posts have been taken with my fixed lens digital camera. I think it does a pretty nice job in macro mode but sometimes you just want to get a little closer to your subject. I photographed each of the landsnails I collected for my PhD research so that I could have a record of their pigmentation, which degrades once you preserve a specimen in ethanol. Obviously, the more detail I could get the better so I borrowed some very exciting toys from the department’s photography office:

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The camera is a DSLR with a 100mm f2.8 macro lens, an extension tube and a twin flash. The mammal crashing this invertebrate-celebrating series is me.

Of course, I couldn’t have a toy like this to play with and limit myself entirely to photographing snails. In amongst those important snail photos I have jumping spiders, hornets, geckos and really anything else that chanced across the porch I was taking photos on. One of the more striking subjects is this red-eyed fly:

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And the head-on shot…

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It turns out the pretty red-eyed fly is Oxysarcodexia taitensis, one of the Sarcophagidae. That family name gives you a clue to how this fly makes its living, it translates as “flesh eating” (it stems from the same root words as sarcophagus, the Greeks believed limestone ate away at corpses sealed in it). Most of the flesh-flies feed on dead animals but a few have earned a place in vertebrate nightmares, horror movies and even medical practice by depositing their maggots in on open wounds.

Relying on dead animals for food is a chancy business. Corpses are usually patchily distributed and there a plenty of other scavangers out there to compete with. This problem is especially bad for the larval stages of insects, without wings to get them to the next corpse their entire future depends on the continued existence of the flesh they are born on. The sarcophogids have developed a neat trick for making the most of corpse when they find one – they give birth to live maggots. Technically, the flesh flies are ovo-larviparous, meaning the larva develops inside an egg which is retained in the female until the larva hatches. Flesh-fly maggots can start eating as soon as they are born, maximizing their chances of getting through their lifecycle before another scavenger eats the corpse they live in.

It’s easy to get freaked out about a creature that spends it’s life eating decaying flesh but we should remember that flesh-flies play an important role in ecosystems. Sarcophigids and other scavengers turn dead flesh into living flesh. WD Hamilton, one of evolutionary biology’s most insightful and original thinkers, recognised the important role of carrion feeding insects in his burial instructions:

“I will leave a sum in my last will for my body to be carried to Brazil and to these forests. It will be laid out in a manner secure against the possums and the vultures just as we make our chickens secure; and this great Coprophanaeus beetle will bury me. They will enter, will bury, will live on my flesh; and in the shape of their children and mine, I will escape death. No worm for me nor sordid fly, I will buzz in the dusk like a huge bumble bee. I will be many, buzz even as a swarm of motorbikes, be borne, body by flying body out into the Brazilian wilderness beneath the stars, lofted under those beautiful and un-fused elytra which we will all hold over our backs. So finally I too will shine like a violet ground beetle under a stone.”.

Talking about talking about science David Winter Mar 10

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I’ve been swamped by the requirements of my real work for the last couple of weeks which has meant I’ve more or less neglected The Atavism just when a set of new scientific posts might have impressed voters in the Research Blogging Awards with this blog’s vitality. I do have a couple of substantive posts on the boil but for now I’m going to resort to flinging out a few links and half digested ideas on science communication

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Let’s start at sciblogs where Ken Perrot has a review of Cornelia Dean’s guide for scientists Am I making myself clear? It’s particularly interesting to read that Dean urges scientists to write for newspapers in the same week that Grant Guilford publihsed some clear thinking in response to nonsense about climate science. The nonsense was in The Herald and no doubt read by thousands, the sensible reply is on some obscure piece of the University of Auckland’s website…

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Dean suggests scientists shouldn’t write books unless they really can’t help themselves. Still, if you sufficiently helpless and want to go down that route there’s been plenty of advice published recently. Nature has a a special ‘web focus’ on writing science books featuring, among others, the inimitable Carl Zimmer. In a similar vein, Brian Switek, the writer behind Laelaps, is about to have his first book Written in Stone appear on the shelves. He has already documented parts of that journey on Laelaps and now he’s going to start a series of posts dedicated to the process

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I don’t think I’ll be writing a pop-sci book anytime soon but, obviousy, I do think science blogs have a place in getting science out to the public so I don’t quite know what to make of this very odd paper on scientific blogging. The authors take a set of posts from 11 widely read science blogs and draw the following conclusions

Science blogs are a virtual water cooler for graduate students, postdoctoral associates, faculty, and researchers from a variety of disciplines and areas of inquiry. The conversations in science blogs are also of “water cooler” quality …

To become a tool for non-scientist participation, science blogs need to stabilize as a genre or as a set of subgenres where smaller conversations may facilitate more meaningful participation from members of the public. Science bloggers need to become more aware of their audience, welcome non-scientists, and focus on explanatory, interpretative, and critical modes of communication rather than on reporting and opinionating.

Which is what happens when you presume 11 blogs is a representative sample of the thousands of people who are writing about science on the net. Of course there are blogs that are pitched at other experts and other blogs that deal mainly in links but presumably that’s because that’s what the authors want to do with their blogs!

If the authors of the paper wanted to see how blogging fits in to describing scientific ideas and news to non-scientists then they might have started, not with 11 blogs plucked from google, but by selecting blogs that are aimed at a lay audience . If you want interpretation and explanation of the day’s science news there are superb writers like Carl Zimmer and Ed Yong to help you out. If you want a scientist to bring their expertise to bear on some topic then there’s a whole mess of blogs (1, 2 3, 4, 5… and another thousand or so here) that do just that (and I like to think The Atavism fills one small niche in that sprawling ecosystem). A thoughtful review of those blogs would have served a real purpose, it’s hard to see that the published paper does. One good thing came from that paper though, I now know there is a Journal of Science Communication, I trust some of the other papers will be more useful. (If you are interested The Panda’s Thumb and Blog around the Clock have more detailed reviews of the paper)

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Finally, congratulations to Elizabeth Connor who has won the inaugural Prime Minster’s Science Media Communication Prize (really, that’s the flowing title given to a prize for communicating difficult ideas…) which gives her $150 000 to undertake a program that focuses on “the mystery intrigue and uncertainty of science.”

Sunday Spinelessness – Survivor David Winter Mar 07

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Until today these Sunday Spinelessness posts have been severely unrepresentative. I’ve talked about molluscs and myriopods and shown you photos of anthozoans and arachinids but nowhere in these posts have I included a post about a beetle. Which is a shame because, to a first approximation, every species on earth is a beetle. Really. Most animals are arthropods, most arthropods are insects and most insects are beetles. In all, 350 000 species have been described so far, about a third of the total number of species from all groups. The star of today’s piece is one of New Zealand’s 4 500 described species.

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I found our star stuck in one of those deadly rhododendron shoots . I guess if I was a cold-hearted documentarian, interested only in recording the happenings of the natural world, I would have left him there to struggle. But, really, I’m just a sucker for handsomely striped elytron so I helped disentangle him from the sticky shoot.

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Those impressive antennae place our specimen in the order Cerambycidae, the long horn beetles, which includes the famous huhu beetle. I can’t identify it down to species but it’s likely in the genus Coptomma (for what it’s worth, the taxonomic shorthand for ’some species in Coptomma’ is ‘Comptomma. sp’). Our Coptomma didn’t seem to have any long lasting effects from his run in with the rhododendron’s sticky trap, he wandered off my life-raft leaf and set about cleaning himself up:

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Sunday Spinelessness – Arachnophobia David Winter Feb 28

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If you read The Atavism regularily you may have gathered I’m quite fond of spiders (1, 2). So, by and large I’m with the Bug Chicks when if comes to arachnophobia. -No spiders will go out of there way to attack people and there’s only a handful of species with toxin that packs any punch to humans so, rationally, there is really nothing to worry about. In keeping with that policy, when this handsome Cambridgea male turned up in our bathroom I saw it as a photo opportunity.

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Then he ran cross my camera, up my arm and lodged himself at home on my neck. All my affection for spiders and rationality with regards to the risks lasted about a tenth of a second. I didn’t actually scream but it’s fair to say my heart rate was somewhat elevated and my movements were restricted. But why? What is is about spiders that freaks us out so much? I did a bit of digging through the academic databases but psychology really isn’t my science and I couldn’t get a clear idea. Researchers in Germany* have shown (at least among German undergraduate students) spiders do have a special place in our fears – people are more likely to respond badly to photos of spiders than other arthropods, even hymenopterans which can prose a more serious threat to people than spiders. But the question of why remains. Evolutionary psychologists have suggested arachnophobia might be an adaptation but it’s hard to imagine that selective pressure applied by occasional spider bites would be sufficient to drive a specific fear of them. Perhaps lots of spiny legs, beady eyes and fearsome fangs just set off enough triggers in the brain to elicit a unique response (did I mention psychology’s not my science…).

I remember reading a more plausible (and even testable) idea about the origin of arachnophobia in one of Steven Pinker’s books that didn’t pop up in my search of the literature. I don’t have the book in front of me (and I can’t even remember which one it was, although it sounds like a Blank Slate kind of an idea) so you might want to take this with even more grains of salt than you usually would with adaptationist ideas. From memory the argument went that we may be born with a general fear of all spiders and snakes but, until recently, would have learnt the few that are actually dangerous in the area we grew up in from our families. With the good guys and the bad guys separated we could stop wasting our energies on being worried by the overwhelming majority of species which are benign. An inbuilt arachnophobia with inbuilt malleability to surroundings. In the West we aren’t exposed to many spiders of any sort in our youth so we retain the childish arachnophobia all our lives. It’s a nice story whether it’s true or not doesn’t seem to have been tested.

Oh, and if my photo of a Cambridgea didn’t put you off Te Ara has a much scarier one.

*Spiders are special: fear and disgust evoked by pictures of arthropods. Antje B.M. Gerdes, Gabriele Uhl, Georg W. Alpers. Evolution and Human Behavior, DOI: 10.1016/j.evolhumbehav.2008.08.005)

Nucleotide diversity – what two new African genomes mean David Winter Feb 26

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ResearchBlogging.org

If you wanted evidence that we live in a post-genomic age you would need to look no further than the headlines in the science section of the newspaper last week. A man dubbed Inuk who lived and died in Greenland 4 000 years ago had dry earwax and might have gone bald if he lived long enough, Tutankhamun was inbred and had a cleft palate and Desmond Tutu has had his whole genome sequenced. What about the science behind the hook? Ed Yong has the the story of Inuk (whose genes tell us about migrations into and out of North America). I’ll leave it the reader to imagine what the broader significance of Titankhamun’s illnesses might be but the publication by Stephan Schuster and colleagues of complete genomes from Desmond Tutu and !Gubi, a Khoisan tribal elder, is an important step in our understanding of human genomic diversity.

As I’ve said before there really is no such thing as the human genome. There are millions of differences between individual genomes and we are each born with about 150 new muations. In an age in which we can sequence assemble and analyse entire genomes in two years understanding the breadth of human genetic diversity is at last an achievable goal and if you want to understand human diversity then you need to look to where we came from. Trace any family tree back far enough and you will end up in Africa and, in fact, most of human history was played out entirely in that continent. Modern humans arose in Africa about 250 000 years ago and only spread out to Europe and the rest of the world in the last 60 000 years, displacing Homo erectus in the process. The migrants that founded the modern European, Asian and American populations would have carried with them only fraction of humanity’s genetic diversity when they left Africa but untill recently genomics has focused on those populations. Until last week the two African genome sequences available to researchers were both from Yoruban volunteers to the hapmap project. Although those sequences are very useful they represent only one tip in the deeply branching tree of humanity

Summary of human genetic diversity redrawn from Campbell and Tishkoff (2008) doi:10.1146/annurev.genom.9.081307.164258 . Numbers in brackets are the number of complete genome sequences from each region available before last week.

To broaden our understanding of African genomes Schuster et al looked to the South of the continent and at two people in particular. !Gubi is a Khoisan (or bushman), a member of a one of the earliest diverging groups within the humanity while Desmond Tutu hails for various Bantu peoples. The results taken from theses genomes along with lower density sequencing and genotyping of other Bantu and Khoisan volunteers reinforces just how much genetic diversity exists within Afirca. By using a method called principle component analysis to reduce a the correlations among millions of single base pair differences (single nucleotide polymorphisms or SNPs) to a smaller set of uncorrelated vectors you can see patterns in the genetic diversity of groups. Applying this method to West African (Bantu and Yoruba), Khoisan and European populations reveals the comparative genetic homogeneity within Europeans and that the difference between the two African groups is comparable to that between either of them an Europeans.

All in all Schuster et al found 1.3 million SNPs that hadn’t been previously identified. Those new polymorphisms will be a boon to researchers searching for a genetic basis to, for instance, HIV restiance in Africa or African-American’s increased risk to type 2 diabetes. Just as interesting as the new SNPs is the discovery of others that have already been associated with diseases even though Desmond Tutu and !Gubi are healthy 80 year olds. A couple of scientists quoted in dispatches seem to think these genomes will act as quality control, allowing researchers to ‘clean up’ polymorphisms incorrectly associated with dieseases in other studies but it seems at least as likely that something more complex is going on. The selective, or health, value of a gene can only be measured against the environment it is expressed in and the rest of the genome is absolutely part of that environment. It’s entirely possible for a gene to be associated with Wolman disease amongst Europeans but to be of no consequence to busman thanks to the different genetic background against which it expressed.

Uncovering the genetic basis of these diseases and untangling the complex genetic interactions that underly populations’ risk to disease still lies in the future but this study also tells us something about our past. Most Khoisan are nomadic hunter-gathers and their ancestors have been for thousands of years, by comparing their sequences to those from agricultural societies you can see the evolutionary impacts of that change in lifestyle. Some malaria resistance genes, scars from humanities long battle with that disease that was amplified when agriculture lead to increased population density, are absent from the Khoisan sequences as are genes for digesting lactose as adults. Though those primitive characters have been retained by the Khoisan they are no more an ‘ancient’ or primitive people than the tuatara is a ‘living fossil’. In fact, there are a large number of bases in which European sequences are identical to the corresponding chimpanzee sequence while the Khoisan sequences diverge – lots of those changes will have been fixed at random but the fact some of them are in genes that are likely target of selection (especially perception of taste and smells and immune responses) suggests they may also have adaptive consequences.

The paper is available to under a creative commons license here and if you feel suitably qualified you can play with their data which has been released on the Galaxy framework.

Schuster SC, Miller W, Ratan A, Tomsho LP, Giardine B, Kasson LR, Harris RS, Petersen DC, Zhao F, Qi J, Alkan C, Kidd JM, Sun Y, Drautz DI, Bouffard P, Muzny DM, Reid JG, Nazareth LV, Wang Q, Burhans R, Riemer C, Wittekindt NE, Moorjani P, Tindall EA, Danko CG, Teo WS, Buboltz AM, Zhang Z, Ma Q, Oosthuysen A, Steenkamp AW, Oostuisen H, Venter P, Gajewski J, Zhang Y, Pugh BF, Makova KD, Nekrutenko A, Mardis ER, Patterson N, Pringle TH, Chiaromonte F, Mullikin JC, Eichler EE, Hardison RC, Gibbs RA, Harkins TT, & Hayes VM (2010). Complete Khoisan and Bantu genomes from southern Africa. Nature, 463 (7283), 943-7 PMID: 20164927

You have to be in to win… David Winter Feb 26

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Research Blogging Awards 2010 FinalistSo, in a fit of egotism and optimism I nominated myself (and a bunch of other people) for the Research Blogging Awards – putting myself forward in the category of “Best Lay-Level Blog”. The finalists were announced today and it seems I made the list. Apparently in the next stage researchblogging.org members vote for their favourite blogs in each catergory. I think it’s safe to say I’ll be out of the running once voting starts but I’m really quite chuffed and… damn it I’m just gonna say it… it’s an honour just to be nominated among real writers lie Brian Switek of Laelaps and Ed Yong of Not Exactly Rocket Science and the bloggers behind The Lay Scientist, Observations of a Nerd, Mauka to Makai and Cancer Research UK’s blog.

Congratulations to all the finalists but in particular to Aimee Whitcroft who does a lot of work behind the scenes at sciblogs and has been nominated in the chemistry physics and astronomy category.

Sunday Spinelessness – Animals that don’t move David Winter Feb 20

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There aren’t many universal laws in biology. Snails proved Dollo wrong, retorviruses did for Crick’s Central Dogma of Molecular Biology and every lesson on Mendel’s Laws of Inheritance includes a section of the exceptions to those rules. Biology’s disregard of human laws notwithstanding, you might think, at least as far as macro-organisms are concerned, you could safely generalise that animals move and plants stay still. But once you consider the ocean even that generalisation can’t be supported; corals, bryozoans, sea squirts, anemones and sponges are all animals that spend their adult life in one spot.

While I was in Masterton for christmas my girlfriend went to Vanuatu (no, you’re right, that doesn’t quite seem fair…) with a waterproof camera so I’ve stolen a few of her photos of coral to illustrate todays sunday spinelessness.

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It’s easy to see why early naturalist thought corals were plants but what you are looking at in those photos is not a single organism, rather it’s a colony of tiny genetically identical animals. Corals are members of the phylum Cnidaria (the ‘c’ is silent) which includes corals, anemones and a diverse bunch of animals we call jellyfish. Such a diverse collection of animals are united under the name Cnidaria because they all employ the impressive nematocyst, a barbed harpoon like cell, to catch and deliver toxin to their prey. Cnidarians have two distinct life stages – a swimming “medusa” (adult jellyfish being the classic example) and a sessile polyp (like the sea anemones familiar to rock pool fossickers the world over). Individual coral colonies (termed “heads”) are made entirely of polyps which reproduce asexually depositing a calcium carbonate base as they grow – the exact pattern in which polyps bud from their parents determines the shape a coral head takes.

Many tropical corals supplement their diets by forging a symbiotic relationship with swimming algae (arguably plants that move…) called zooxanthella, the algae get carbon dioxide from the coral’s respiration while the coral gets energy from the algae. This relationship is of huge importance in the tropics because it allows corals to grow in those region’s warm, nutrient poor waters. Without coral reefs, made from thousands of years of calcification from corals, tropical waters would be nowhere near as biodiverse as they are now and people whose love of animals only goes as far as that peculiar phylum Chordata should care about that:

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As always, you can click on any of those photos to see higher-resolution versions.

Sunday Spinelessness – robber fly David Winter Feb 14

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robber fly eating a blowfly

I’ve said before that the bugs in my parents’ back yard seemed especially hungry over the Christmas break. Above you see more evidence to this fact. In the lower half of the photo is a robber fly and above is its meal, a blowfly of some sort. I’ve never seen live robber flies in Dunedin (though there is a dead one here) but the species captured above seems to be reasonably common in the Wairarapa. The first time I spotted one of them I struggled as to where to place it among the insects. The robber flies have long slender bodies and large rounded eyes which misled me into thinking that first sighting might be a small dragonfly. The real taxonomic position of the robber flies is spelt out in bright yellow in the next photo.

robber fly - check out the halteres

That bright yellow structur under the main wing is a haltere. Most insects have two sets of wings and we can tell quite a lot about where a given species fits in the insect scheme based on how it uses those two. Dragonflies and damselflies use both for flying, in beetles the forewings are “sclerotised” into a rigid case that protects the flight wings and the “true flies” ( order Diptera) have turned thier hind-wings into halteres – greatly reduced wings which act as gyroscopes stabilising the flies’ flight and allowing them to perform aerobatic tricks. The robber flies from the extremely widespread and speciose family dipteran family Asilidae which includes a staggering 7 000 described species, meaning there are rather more robber fly species in the world than there are mammalian ones.

The features that led me to mistake that first robber fly that I saw for a dragonfly are likely the result of convergent evolution – dragonflies and robber flies are both predators that specialize in taking other insects on the wing. The robber flies differ from odonates in having piercing mouth-parts which they use to inject first a neurotoxin then digestive enzymes into their prey. The blowfly in the photos in this post is paralysed and its tissues are in the process of being liquified and sucked through the robber flies mouth parts. But ever before the neurotoxin entered the blowfly’s body it was done for, the robber fly’s strong “raptorial” legs are covered in sharp spikes and end in claws that offer little hope for escape once a catch is made.

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