Discover The Loom all over again

Carl Zimmer has returned to his roots, joining Discover as a columnist and, concomitantly, moving The Loom to Discover's servers. But because you're a clever wideawake person you read The Loom regularly, and so know all this already.

Forget the polar bears, this is serious

Aphids, eh. Extremely interesting insects, you know. Most of the time, that bunch of aphids on a plant is a clone. The aphid wimmens has aphid babies without aphid daddies being involved. Genetically all is much of a muchness, and when a predator eats a few of the insects, it is really not as though indviduals have been extingished so much as that the aphidical aggregate has, emm, lost a couple of toes. (Possibly the aphids being eaten view things differently.)

And this is a banner year for the wee critters, to be sure. Took the new bike out for a spin today. Within a few minutes, my shirt and arms were festooned with aphids, and though I did not really want to enquire into my perceptions of the matter too deeply, it is pretty certain I inhaled and/or ingested a fair few.

But forget my shirt and my lungs, the local aphid biomass is astonishing. There are lots of sorts of aphids, but rather than come over all taxonomic here, I will divide them into the green sort and the black sort. And I didn't even have to do that, for there are plenty of both. The low shrubby green plants bear the green kind, our trees the black sort. The hazelnut in our garden is not thriving this year (it grew last year as though on steroids; it was almost a nuisance). Turn a leaf and see why: the underside is a thick carpet of aphid. There's a small tree in the tiny garden before the house; vast stretches of its limbs are black with the insects and its leaves glisten with the sweet sugary honeydew they are constantly shitting.

All well and good, normally, because there is a circle of life thing that goes on here, and the aphids play the role of the zebras and antelopes. This year, though, Simba's gone missing.

Ladybird beetles ("ladybugs" in North America, though they aren't bugs -- they eat bugs) take on the lions' role in miniature. Beautiful little insects, they really do look like the classic VWs. Even people who hate insects often like ladybirds, probably because they are so pretty. But they're also useful. They make aphids go away, you see. Whether as cute little adults or as the uglier and more threatening-looking larvae, these insects hoover aphids up wth an unstoppable voracity.

Except that there aren't any this year. Based on previous years' experience, at about this time I'd expect to see vast armies of ladybirds ploughing furrows through the aphid ranks. But there are none. Since last winter I have seen one adult and no larvae.

Where are on earth can they be? The polar bears might be losing habitat to global warming, but I don't think we can blame that for the disappearance of the ladybirds. Indeed, we had a mild winter so I would expect it to be a hellish summer, bug-wise. And so it's shaping up to be -- for everything but the Coccinellidae.

And without them I'm really not sure what to do about the aphids. A few years ago I tried spraying them with water in which I had soaked a few packs of cigarettes. (The nicotine was supposed to kill them.) This was a great plan, except that the nicotine-water was dirty and unpleasant and didn't work very well.

Anyway, if you are ladyird and looking for work, stop by my place. I'm sure we can come to terms.

Reasons to make sure ALL your windows are closed, part 8,927

The family are away for two days, so of course I went to see Iron Man -- nothing like a bit of subtle intellectual diversion to keep the synapses limber. Afterwards I dined, as I so often do when the family are away, at the Upper Westside (not great cuisine, to be mercilessly frank, but simple, cheap and good. Comfort food. Plus, Ralf the host shares my deep affection for NYC). I was gone oh, perhaps four or five hours all told. Now, our kitchen and living room give onto a terrace via double glass doors -- I think they're called "French windows"? -- and above each is a sort of small transom window that tilts open inward along the top. I left the living room transom open when I left, the better for air to circulate.

As things transpired, this was a mistake.

So I came home and there I was futzing about in the office upstairs when I heard noises below. These I ignored at first, as I was surely alone in the house. But then I heard them again, and then again once more. Hmm: better check it out. (If I were in Texas I've no doubt I'd have been cocking the "hog's leg" at this point.)

I walk around the ground floor, puzzled. Nobody there, nothing out of place. Where were those noises coming from, then? And that's when I see the intruder, standing on the living room sofa.

It was a thrush. Possibly a blackbird but, though I am no ornithologist, it looked not quite black enough, its bill not quite yellowy-orange enough to be that sort of bird. But it was at any rate a close relative. A great many thrushes visit our garden. (A great many blue tits too, and the occasional crow or jay or magpie. Starlings, when the cherry tree is in fruit. But, oddly, almost never a sparrow). As the thrush lacked opposable thumbs, I quickly discounted the possibility it had opened the French windows, entered and then shut them again. No, clearly the bird had come in, quite literally, over the transom.

Am impressive feat for a creature with a brain the size of a pencil eraser, but one that obviously maxed out its cognitive potential. For though it had got in, it could not get back out. There was evidence (we'll come to that in a moment) that it had spent a lot of time near the window, gazing longingly into freedom. Had it but looked up and a bit to the left, it might have seen the way out.

By the time I found it, it had moved in away from the window to the sofa. It gazed at me warily, I thought, but without undue alarm. Perhaps it knew I meant it no harm, perhaps it was too exhausted and confused to care much any more one way or the other. It was in its unadorned way a pretty bird, and in a very abstract (but only in an abstract) way I found its presence pleasant. Still, it had to go.

Getting rid of it was harder than I thought it would be, though. I threw open the French windows, but the thrush sat still. I gesticulated and made booga-booga noises, and that did prompt it to fly, but only in circles round the living room, finally landing on the sofa once more. Then I twigged: lights out! Once the room was darkened it instantly saw its way out, and off it flew. Good luck, little thrush, and maybe you'll find some birdish way to warn your children against transom windows!

Now, then. Years ago I kept a few budgies and a cockatiel as well as a mynah. The Germans have an interesting way of distinguishing among birds. Our small Psitticaformes they call Trockenfresser, meaning birds that eat most dry stuff, seeds and the like; our mynah by contrast would be a Weichfresser, an eater of soft foods like bugs and fruit. This distinction has an important practical implication. What our budgies shat was small, dry and inoffensive, in size and consistency rather like a matchhead, and the occasional accident whilst they were flying freely was no big deal. With the mynah, this was not the case; emphatically not the case.

This evening's observations established that thrushes are Weichfresser.

Indeed, if any ornithologists reading this post will tell me how frequently a thrush shits, I can tell  you to within a very close tolerance how long the thrush was in our living room. Even as a non-specialist, though, I think it was there a long time. And a lot of that time it spent perched atop my favourite armchair.

Cleaning things up was easier than I'd have thought. But still: thrush shit. So let this be a lesson to you all -- keep those transom windows closed when you are out watching Iron Man!

The prosody of the genes

PZ Myers's Pharyngula site is blessed with a regular commenter who uses the nom de plume "Cuttlefish". Cuttlefish's comments invariably take the form of verse: witty, on point, and technically sound. (This versifying mollusc knows there is a lot more to poetry than putting rhyming words together.)

It's always a pleasure to read Cuttlefish's offerings, but the most recent one is an astonishing technical accomplishment. PZ's post was a response to a correspondent who didn't see how chromosome numbers could change, and asked for an explanation. PZ explains, at length but in easily digestible form, how chromosomes can break apart and reform such that (out of the same genes) entirely new chromosomes are built. And Cuttlefish, in comments, has created a wonderful poetic analogue to PZ's story of the genes. This isn't just amusing versemaking, it is poetry in the highest sense: making the words one chooses and the forms in which one arranges them precisely appropriate to the underlying concept one wants to convey.

You can find a lot of Cuttlefish's poems at this convenient website, BTW. And don't miss the post Cuttlefish was commenting, either!

Spreading the good news of truth

If you want to learn something about a group of dishonest, contemptible people, go here: Expelled.

If you want to help make other people aware of that website, go here for a helpful suggestion.

Kin deletion explained!

Pity the poor makers of slasher films. It's getting harder and harder to find a hook to hang a film from. Long gone are the days when all you needed was a half dozen or so teenagers and a remote campsite. No, these days you need evil Slovakian youth hostels or the seven deadly sins. And now that those ideas have been taken, where does the would-be filmmaker turn?

Why, to evolutionary theory, of course. Before we proceed, let me introduce you to the Price equation. Here it is in its full form:

"Umm, yes," you might be asking, "but what on earth is it?" Well, as Steven Frank put it in the Journal of Theoretical Biology, it is nothing less than "an exact, complete description of evolutionary change under all conditions". What, all of evolution explained in a handful of tiny squiggles? Apparently, yes. (If you follow the link to his paper, Prof. Frank will walk you through what the squiggles mean.)

George Price, who derived the equation that bears his name, was an American chemical engineer. In the last years of his life, though, he turned his attention to evolutionary theory. Moving to London, he wrestled with William Hamilton's ideas on kin selection, set forth in a pair of seminal papers (ignored at first, they eventually became among the most heavily cited in the discipline). Price, a newcomer to the world of biology, thought about Hamilton's equations for a while, then reworked them into his own equation and presented it to Hamilton saying, more or less, "Here. Now it explains everything, not just kin selection".

Kin selection, by the way, means pretty much what you'd think. Consider an organism that does something -- it could be anything -- that reduces its own reproductive success. Hamilton's classic example is the worker bee, who devotes her life to helping her mother reproduce rather than making babies of her own. Because bees have unusual genetics, kin selection operates especially powerfully on them. But as Hamilton always insisted, he wasn't trying merely to explain worker bee celibacy, he was thinking about a general principle that applies to all organisms. So let's call our organism A, and what it does, X. At first blush, you'd think that if X had a genetic basis, it would be eliminated by natural selection very quickly, because A would fail to pass the gene causing X on to a new generation. A, in other words, has a fitness of 0. But that's not necessarily correct. Fitness isn't about having kids, it's about getting copies of your genes into the next generation. And A's body isn't the only place it stores copies of its genes; some of its genes are also in its close relatives. If A, by refraining from reproducing itself, helps its reproductive relative B pass on more copies of the gene for X than A and B together would have passed on had they each tried to maximise their own reproductive success, natural selection will favour A's strategy.

So what does this have to do with slasher films? Not a lot, really; but that didn't stop our filmmakers. They have -- sort of -- made kin selection, as explained through the Price equation, the inspiration for their opus. This title of this masterpiece is wΔz, which you'll recognise from the equation above. But apparently its makers are not targetting an audience familiar with mathematical notation, because it is (I am not making this up) to be pronounced "waz".

Here's the idea: the police find corpses with the Price equation carved into them. The killer's shtick is to make victims choose between their own lives and the lives of their kin. But if the filmmakers wanted to create suspense, they were unwise to use kin selection as their device, because there is no suspense at all involved. Should you ever find yourself in the clutches of the wΔz killer, your decision is an easy one. As Haldane would have advised you, if the kin whose lives you must weigh against your own are less than or equal in number to two siblings or four cousins, they're out of luck.

The film is apparently already out in America, though SFAIK not in these parts. Perhaps it will never be. I am not expert in these matters, but the impression I have is that this one just might bypass the Kino altogether and head straight for the video shop. Pity, really. I'd be delighted to see a horror film that takes the Price equation as its premise, but this one seems too stupid for words, let alone for elegant mathematical symbols.

The real story of the Price equation is much more interesting than any slasher flick. So is the story of Price himself. George Price was a brilliant but deeply troubled man. He was a tragic figure, in the proper sense of that term: destroyed by the very qualities that made him great. If you don't want to wait for the blockbuster Hollywood biopic (Brad Pitt as Price, Jude Law as Hamilton, and Scarlett Johansson as the brilliant young post-doc?), you'll find a fascinating and tender recollection of the man in the collected papers of his friend and colleague Hamilton. And science writer Andrew Brown's The Darwin Wars is, in good measure, about Price and what his equation means. Steven Frank's 1995 J. theor. Biol. paper, linked above, is another good introduction, though a bit of a hard slog for laity like me; it is less about the man than about his work, the eponymous equation as well as his two other major contributions to evolutionary theory.

Distributed intelligence at work

Like most people, you probably read Proteomics over your breakfast cereal. If so, your eyes surely goggled when you saw the review article "Mitochondria, the missing link between body and soul: Proteomic prospective evidence" by M. Warda and J. Han. If you're a Star Wars obsessive, you'll have asked yourself, 'If they're fanboy enough to write an article like this, why can't they spell "midichlorians" properly?' But if you're a scientist, you'll be asking WTF that word 'soul' is doing in a journal about proteomics (or, really, in any scientific journal).

PZ Myers noticed the review and, after the obligatory eye-goggling, wrote about it at Pharyngula. A very odd article altogether, thought PZ. Lots of sound science in the thing, actually; but tucked in among the sciency bits are nodules full of screaming waka-waka.

And here's the waka-wakiest:

[T]he points that show proteomics overlapping between different forms of life are more likely to be interpreted as a reflection of a single common fingerprint initiated by a mighty creator than relying on a single cell that is, in a doubtful way, surprisingly originating all other kinds of life. [Emph. added.]

Now, here's something to induce spontaneous orgasm in intelligent-design creationists. At long last, they can point to a peer-reviewed paper! In a respectable scientific journal! That proposes a creator! A mighty one, even!

Their orgasms are premature. As I learn from the many working scientists in PZ's comments thread, review articles like this, unlike original papers, aren't necessarily peer reviewed (depends on the journal, apparently). But that's the least of their problems.

First, Proteomics has not gone over to the dark side. One of the commenters contacted the journal's editor (a proteomics guy at UCD's Conway Institute), whose reaction was 'WTF? WTFF? Oh Jesus fuck, no!' (or words to that effect). Still, it's hard (though not altogether impossible, as some of PZ's commenters note) to see this as anything but a (quite grave) instance of editorial falling-asleep-at-the-switch.

Then one commenter mentioned, half in jest, Johnson's famous (though possibly apocryphal) judgement of a literary work: it was good and original; but the original parts weren't good, and the good parts weren't original. Johnson's judgement turns out to be remarkably apposite in the case of the Warda and Han review article. One commenter noted a brief passage of text that looked suspiciously like something he had read elsewhere. He compared the two passages, and yes: virtually identical. Within minutes, the many working scientists among the Pharyngula readership were pulling volumes off the electronic shelf and running text comparisons.

And, as it turns out, if you leave out the waka-waka (which the authors do seem to have made up on their own), but for a single paragraph the entire article is cobbled together from other people's (legitimate) work. I gather, from what the scientists write in comments, that plagiarism is grounds for a journal to instantly retract an article (even one that doesn't amble off into mutterings about souls). Doubtless Proteomics (according to the proteomics wonks in the thread, a respectable but not a leading journal in the field) will promptly do the right thing; but I'm afraid they don't come out of this looking good.

For Warda and Han, by contrast, this incident can only be career-enhancing. Tenured positions at Liberty University and lucrative fellowships with the Discovery Institute glitter ahead. Well; Warda appears to be a Muslim, so maybe Liberty isn't in the cards. But Harun Yahya can probably endow a chair for him at the Islamic equivalent.

So, some creationists sneak a paper into a legitimate journal, and what happens? The real scientists shoot it down in flames... in a matter of hours... while off duty... in the comments thread of some guy's weblog. Science, as the scientists like to tell us, is self-correcting. Surely there have been more important instances of self-correction than this; but none more awesomely fun to watch.

Under the circs, I'm quite happy that the ID creationists have finally found the paper they've been longing for. I strongly encourage them to make the maximum possible use of it, and to hold it up to the public as an example of the sound, fruitful science that ID creationism can produce.

Beneath the Übercat

Given our many fiercely allergic relatives, we have no cats, hence this is all of merely academic fascination to me. But perhaps you will find it practical as well as cool. At Zooillogix, Los Bros Bleiman point to a useful set of instructions for teaching one's cat to use the toilet. The instructions are from Charles Mingus. Yes, that Charles Mingus.

The late, great bassist even tells us that his own toilet-trained cat learned to flush.

Shocking Northern Ireland killings

This is just too depressing. One would have thought the days were now gone when this sort of thing could happen.

Friday (mostly) non-arachnid blogging

The focus today is not on spiders but on some of their distant cousins. I saw them on Formentera during our holiday this summer.

The island's real star was a wasp. These insects are gorgeous, and everywhere. They zip about, endlessly hunting up in high corners; for spiders, I guessed. That, plus their long legs, led me to suppose they might be pompilids. Then I picked up a copy of Xavier Canyelles Ferrà's Insectes de les Illes Balears at the Llibreria Tur Ferrer in Sant Francesc. And so I discovered that this was no pompilid but a sphecid, Sceliphron spirifex. The Catalans call it tallanassos or vespa del fang; we would call it a mud-dauber. Like pompilids (and unlike some other sphecids), though, they hunt spiders to provision their larvae's nests. They are endemic to Africa, but have also crossed the water, extending their range to Europe's Mediterranean regions.

S. spirifex are large and beautiful. They are black, except for their exaggeratedly long, thin petiole and the bands on their legs, which are yellow. They are not at all aggressive. I would imagine their sting hurts terribly, but they are unlikely to use it. They are solitary wasps who set up their young with a supply of food and then leave them, hence they lack the hive- and brood-protecting instinct altogether. Fear of their sting is not why I couldn't get a good picture of them; I simply couldn't get them to hold still long enough at close range. Here's a picture of one, with apologies for its crappiness:

They are truly the Lamborghinis of waspdom. You should really get a look at some decent photos of them. And you'll find plenty of those at Luciana Bartolini's website. She even lets the wasps build their nests on her bookshelves (and books). Some of these she opens to reveal the horde of paralysed spiders within (I recognised an unfortunate Araniella cucurbitina in one photo). I should note that the site is in that most beautiful of all languages, Italian. But even if you know no Italian, you should be able to find your way round. Be sure to visit the page showing the construction of a nest! And as long as you're at her site, browse around a while: Ms Bartolini has some amazing photos of insects, spiders and other small creepy-crawlies.

Many people find spiders creepy. I don't find any animals "creepy", but sometimes I have remind myself of this principle when I look at these insects:

It's a bug, in the strict sense of the word. That is, it's a heteropteran, an insect with mouthparts modified to pierce and suck. This one is an assassin bug. It sneaks up on other insects, unfolds that long pointy proboscis tucked down into its chest in the picture, and sticks it into its prey. It pumps the prey full of digestive enzymes, then sucks up the resulting goo. It's as though you jammed your nose into a lamb chop, squirted out a load of caustic snot, then snorted it all back up again. Assassin bugs will bite humans if bothered by them; the pain is said to be exquisite. I was in no mood to verify this empirically when I found this specimen next to my bare foot on the terrace at night. I popped it into a little bottle and thence into the freezer to prepare it for its photo session the next morning.

Here's an altogether more agreeable insect, or at least, what's left of it:

You've probably seen these before: the empty husk of a cicada nymph that has climbed up from its underground lair, split its skin down the back and emerged a winged imago. According to Canyelles there is but one species of cicada found in the Balearics, Cicada orni, so I suppose that's what this is. You can hear its cousins singing on the jukebox down in the left margin of this page; those American cicadas are, however, from other genera (Magicicada and Tibicen, respectively).

Here's another nocturnal terrace visitor. You'll note straightaway that this creature is no insect; too many legs, for one thing:

It's Scutiger coleoptrata, the house centipede. They're instantly distinguished from other centipedes by their long, fringelike legs. There's another, less obvious but important difference: house centipedes have faceted compound eyes, rather like an insect's. As it happens, this specimen is in its ancestral home, for S. coleoptrata originated in the Mediterranean basin. They're all over the place now, though. We'd occasionally see them when we lived in Brooklyn.

Here's another non-insect. (You didn't think I'd leave the spiders out altogether, did you?)

She's a darling wee salticid, is what she is. PZ Myers was kind enough to give me one for my birthday. I hope he won't think me unappreciative if I say I find this one even cuter.

They're stridulating our song

Scroll way down the page and you'll find a jukebox full of dope jams. Old school jams at that -- really old school. They've been topping the charts for millions and millions of years now.

If you want a jukebox for your own site, visit the Songs of Insects webpage. Send them an email, and they'll send you the code.

By the way, I found the jukebox on Zooillogix, a new ScienceBlogs site whose authors are siblings despite being from different phyla (Andrew is an isopod and Benny an aye-aye). I've added it to my blogroll, and you should add it to yours as well.

Stones unturned

Today, I learn from Jon, is International Rock Flipping Day. Go out to your garden, flip over a likely-looking rock, and take pictures of the wee beasties you've uncovered. Then replace the rock. If a giant pulled the roof off your house, you'd want him to put it back on, wouldn't you?

My problem is that the only rocks in our garden are very heavy, very deeply-embedded flags. Can't flip 'em for love nor money. But that's OK, because these days I don't need to search for wee beasties -- they come to me.

Some of you may know that I find spiders interesting. We have a lot of them around the house this year, Pholcus phalangioides -- the "daddy longlegs spider" -- for the most part. They are hardy and synanthropic, and after the mild winter we've had a bumper crop. But in the last few days, we've been seeing a lot of Tegenaria atrica. Found one in the dining room three nights ago. Two in our bedroom yesterday. The kids came across one at the foot of the stairs this morning. We put him in a plastic box for a while to observe him (he didn't do much).

If you're from anglophone Europe, you might know Tegenaria as the "house spider". Or you might know it as the "fecking monstrous great hairy fecking spider", and then start screaming. I quite appreciate that not everybody shares my affection for arachnids, and if you want to cultivate that affection, perhaps it's best to start with something a little easier than Tegenaria. For they are large, and hairy, and fierce-looking. Their legspan can easily top 8 or 9 cm.

They are gentle souls, though. They spend most of their lives on a large sheet-web; in a back corner is a silken funnel into which they disappear when alarmed. If you ever see them wandering about, it is almost certain you are looking at a male who has struck out in search of a mate. Sometimes you'll find him in a tub or sink. He didn't come up through the drains. He slipped in and can't get back out. Pick him up, why don't you, and put him in your cellar. (Trap him in a small glass if you don't want to touch him.)

These spiders have visibly large fangs, and could certainly give you a painful nip if they wanted to. Here's the thing, though: they don't want to. I've corresponded with a Belgian researcher who is trying to determine which common spider has the most painful bite. (He serves as his own guinea pig.) Apparently it's not unusual that spiders need to be goaded into biting, but T. atrica wouldn't bite him no matter how much he poked and prodded.

We've managed to catch almost all the T. atrica males who've crossed our path over the last few days. We release them in the cellar, for it's there that they're likeliest to find what they're looking for.

But they might find more than they bargain for. Remember Ph. phalangioides? They are smaller and more delicate than Tegenaria, but love catching and devouring them. In the cellar, by the coal-chute, I found a Pholcus (not even fully grown) who had dispatched a Tegenaria and was slowly eating him. (This will take her a good couple of days.) Her belly was strained almost to the bursting point.

I hope the fellows we released will escape this grisly fate; or at least, have the chance to mate before they meet it.

Routing around the damage

PZ Myers notes that a Turkish Muslim creationist (no, they're not all biblethumping Christians) is upset at critical posts on certain Wordpress-hosted websites and has managed to get a court order blocking access from Turkey to all Wordpress sites. That's just insane.

PZ says:

It sure would be a shame if someone echoed all those urls, and these anti-creationist blogs got more publicity and attention because of a stunt by Adnan Oktar, now wouldn't it?

It would, to be sure.

http://adnanoktar.wordpress.com
http://adnanoktarveislam.wordpress.com/
http://fitikado.wordpress.com
http://oktarbabuna.wordpress.com
http://adnancilar.wordpress.com/
http://adnanoktarveislam.wordpress.com/
http://whoisharunyahya.wordpress.com/
http://adnanoktargercekleri.wordpress.com/
http://quiestharunyahya.wordpress.com/
http://harunyahyaarabic.wordpress.com/
http://safsataciharunyahya.wordpress.com/
http://savsatalaracevap.wordpress.com/

For those in Turkey, PZ notes:

Here's a way to get around the block — you can still read and post to Wordpress blogs in Turkey if you use OpenDNS. Spread the word.

You heard the man. Got a blog? Got a cut-and-paste function? Get busy.

What difference does a letter make?

I am a mutant.

Unfortunately, I cannot teleport or shoot death rays out of my eyes. But, if nothing intervenes to keep me from doing so, I might live longer than you.

You too are a mutant, of course. I doubt there's a person alive whose DNA hasn't undergone some sort of copying error. Most mutations don't seem to do anything. Some are harmful. Occasionally, one confers a benefit. My mutation is one of that last sort, though for reasons to be discussed downpost, I suspect that it does not improve fitness. It might benefit me personally, but in evolutionary terms it could well be irrelevant.

The mutation, in case you were wondering, is as simple as can be: the substitution of thymine for cytosine at a specific position in the mitochondrial DNA. Unlike the rest of your DNA, the mtDNA is not found on the chromosomes in the cell nucleus. Instead, it is kept in little scraps inside the mitochondria themselves. That is because mitochondria were not originally part of the cells they now live in. They were free-living bacteria, utterly unrelated to us but closely related to the Rickettsia that cause typhus and Rocky Mountain spotted fever. The bacteria that became our mitochondria, however, were much more benign. Instead of sickening us, they enable us to use oxygen, greatly increasing the efficiency with which we generate energy. So we decided to keep them, and now they are an integral part of us. When I say 'us' in this paragraph, of course, I refer not to H. sapiens but to some single-celled eukaryotic ancestor an unimaginably long time ago. And incorporating those useful bacteria was one of the best ideas our one-celled ancestors ever had. The eukaryotes that took on mitochondria have flourished (you are one of them); those that didn't went extinct long ago. (There are a very few sorts of modern eukaryote that don't have mitochondria. But these have lost them secondarily. Eukaryotes that primitively lacked mitochondria have disappeared entirely.) Richard Dawkins has a wonderful description of our acquisition of mitochondria in the 'Great Historic Rendezvous' chapter of The Ancestor's Tale.

One of the oddities of mitochondria is that, like any good bacterium, they reproduce asexually. All your mitochondria descend from those in your mother's egg before it was fertilised by your father's sperm. Your father's mtDNA did not combine with your mother's as did his nuclear DNA. Your mitochondria are clones of your mother's, and her mother's before her, and so on and on. Any variation in mtDNA arises solely through the occasional random mutation; your father contributes nothing to the process. And as we shall see in a moment, the matrilineal descent of mtDNA is important to this post.

In a 2003 paper in the Proceedings of the National Academy of Sciences, Jin Zhang et al. report on a strong correlation between longevity and the C-T transition recorded in my mtDNA. The paper speculates that the mutation might confer enhanced immunity to various cancers common to old age, but doesn't really say why the mutation is often found in the long-lived. They merely note that one finds it a lot of the time. Zhang and colleagues focused on a population in Italy but, as they note, the mutation crops up in pockets pretty much all over the world.

The PNAS paper was brought to my attention by a fellow mutant. One day I received an email asking me if my maternal ancestors came from a certain region, and if they were long-lived. 'Why, yes to both', I answered, somewhat mystified. In explanation, he forwarded me a copy of the paper. He had, he told me, been chasing down the mutation in a database, and came across me. On a hunch, he asked me his questions, and his hunch proved right.

As I said, this mutation is in the mtDNA, and because mtDNA is inherited only in the female line, it's easy to trace. I know exactly where mine comes from (as it happens, very close to where my correspondent's maternal line has its roots). And my maternal line is long-lived. My grandmother (for example) will soon reach 100, and her elder sister crossed that threshold three years ago. They're all like that. (When my grandmother's brother died at 86, everybody thought his death shockingly early.)

Zhang et al. think the mutation is selected for. However nice it may be to have, though, I question its adaptive value. By definition, the benefit it confers (assuming that the correlation turns out to be causation) comes at the back end of a long life. By that time, you'll already have done your Darwinian bit: popped out a few sprogs, raised them up to the point they can reproduce themselves, even perhaps supported them beyond that. But by the time you reap the mutation's benefit, your work is done; dozing by the fire is unlikely to improve your descendants' fitness. If the mutation enhanced fitness (and not merely the length of an individual's life), I would have expected it to be a lot more widespread. It isn't, though. Indeed it is pretty rare, though found in many places. And that's what I'd expect of a mutation that confers no fitness benefit -- it pops up from time to time, randomly and all over the place, but never gets within a million miles of fixation.

And of course, there are any number of things that can happen to prevent one from realising the benefit of the mutation. A bullet, a bacterium, a hungry tiger, a heart attack; death hath so many doors to let out life. As I mentioned in my previous post, my uncle has just learned that he will be lucky to see out his biblically-allotted threescore and ten; yet he bears the same 'mutation for longevity' that I do.

Hot arachnid-on-arachnid action

Every now and then I get email from the Secretary of the ISA (currently, the Humboldt's Jason Dunlop) and to be honest, there is little of it I'd be minded to share with you and, unless you share my arachnophilia, even less likely to interest you.

But then again, sometimes I get stuff like this, which Jason forwarded from Jordi Moya-Laraño:

As a co-organizer of the 23^rd European Colloquium of Arachnology I have been asked to organize a symposium on a current topic in arachnology. As my interests go I decided that a good subject for a symposium would be “spider sex” in the broadest sense possible. In view of recent published papers that are certainly major contributions to the advance of knowledge in spider sex  ... I thought that it would be pertinent to have a symposium in which we can all discuss the state of the art of a very promising field for years to come. [Emph. added, as though it were needed]

Boom-chicka-boom! And you thought ethology was just boring wholesome stuff like having baby ducks imprint on you.

Anyway, if any of you out there are interested in attending a Spider Porn Fest (held on the Catalan coast as an added bonus), let me know in comments or by email, and I'll forward you Jordi's contact info.

Friday arachnid blogging: Spider of the Year 2006

It's not really spidering season, alas. But it is that time of year when prizes are handed out, to spiders no less than to films. Brokeback Mountain, the gay cowboy film¹, cleaned up at the Golden Globes. Now I'm sure the voters focused primarily on the merits of the film, but they'd be inhuman if they didn't enjoy the fact that selecting Brokeback Mountain would annoy the troglodytes. In the same way, the selection of Misumena vatia (Clerck 1757) as European Spider of the Year honours an unquestionably excellent arachnid, but will surely piss off Meta menardi (Latreille 1804) and Nesticus cellulanus (Clerck 1757).²

(The photo, BTW, I swiped from the AraGes site.
The photographer is Heiko Bellmann, a masterful portraitist
of creepy-crawlies, to my mind every bit as good as
the Preston-Mafham brothers, and that is high praise indeed.)

M. vatia is a thomisid crab spider. I've written about these before. They are among the spiders that even many inveterate arachnophobes can tolerate, more or less; probably because many thomisids are beautiful, and all spend almost all their time immobile. Many of them, including our Spider of the Year, are specialised ambush-hunters living on flowers. They're out in plain sight, but so well camouflaged that you probably won't see them. Nor (to their great misfortune) do the bees, wasps, flies etc. -- many of them larger than the spiders -- that visit the flowers. M. vatia grabs them with those great raptorial forelimbs and, with her tiny fangs, administers the killing bite; for preference, just behind the head. When she succeeds in biting her prey here, it is instantly immobilised. If she bites a limb or what have you, her venom takes longer to have its effect, and she must hold on tight and try to avoid stingers, jaws etc.

Many spiders have evolved 'teeth', spiky projections on the inside of their chelicerae. The chelicerae are the spider's 'jaws', hinged clawlike things with the fangs at their ends. With these teeth, the spider can crunch and munch her prey as she slurps the liquefied innards into her mouth. Over to the right you'll see a drawing that shows toothed chelicerae, from Pedro Cardoso's sadly dormant aracnis website. The chelicerae are, in origins and evolution, utterly unrelated to your own jaws; but for spiders with cheliceral teeth, they are remarkably similar in function.

Misumena vatia, though, has no 'teeth'. She has access to her prey's insides only through the tiny holes her fangs have punched in its exoskeleton. When a spider eats (how shall I put this delicately? Hmmm.... I can't), she spews digestive fluid into/onto her victim, waits a bit for it to dissolve the prey's insides into a sort of soup, then sucks the fluid up using a very powerful 'sucking stomach'. (Wayne Maddison has an excellent illustration and explanation; though his page is about jumping spiders, this bit applies to them all.) Toothed spiders mash their prey to a pulp in extracting the fluids, but toothless spiders like M. vatia leave their victims externally unharmed, turning them into exquisite hollow shells. Indeed, so effective are these spiders' camouflage that, despite their often brilliant colours, you might be most likely to notice them only indirectly, by the unnaturally immobile bodies of their prey. In his classic of observation, The World of Spiders, WS Bristowe relates a charming anecdote of a field trip he took with an eminent lepidopterist. Bristowe himself was looking, without success, for a crab spider. Then he noticed a beautiful specimen of the butterfly his friend was seeking. Oddly, the insect kept perfectly still for minutes on end. Then it all clicked into place for Bristowe; moments later he had his spider, and the lepidopterist had a perfect, if empty, specimen.

Misumena vatia hasn't much in the way of a common name. Some people call her the Goldenrod spider, though she has no special affinity for the goldenrod; others call her the Variable flower spider. Neither name has really caught on, but the latter at least is accurate: she lives on flowers, and she is variable in colour. Spectacularly so; she may be purest white, bright yellow, or brilliant magenta (or a mix: white with magenta stripes, yellow with dark brown, etc.). A single animal can vary her colour dramatically, but she is no octopus or chameleon -- a full change takes days, not minutes or seconds.

I once found a beautiful specimen on the grounds of a German chemical/pharma concern that I was visiting on business. Having just had lunch, we were taking coffee in the small garden behind the company canteen when I spotted a large, pure white spider on a yellow flower, and instantly whipped out one of the little glass bottles I carry everywhere. (Serve the spider right for choosing the wrong flower for her colour-phase.) I took her home, where she would have taken up permanent if posthumous residence in a bottle of 70% ethanol, but the children found her charming and pleaded for her life so eloquently that I released her into a flower-bed on the balcony. To be honest, I would have been as charmed as the children to have a beautiful crab spider living amongst our flowers; but she swiftly disappeared, the ungrateful creature. I suppose she may well have disappeared down the gullet of a bird; after all, she had already proved herself rubbish at camouflage.

I should note, BTW, that the European Spider of the Year award is also a pleasing illustration of European integration in action. The awards were initiated by my own 'home' society, the German/Austrian/Swiss Arachnologische Gesellschaft eV (AraGes). AraGes were later joined by Belgium's Arachnologische Vereniging/Société Arachnologique (ARABEL); and this year, for the first time, the Spider of the Year was chosen on a pan-European basis under the auspices of the European Society of Arachnology.

¹But then, as somebody once said on the internets, every cowboy film is a gay cowboy film.

² My apologies, for this is an arachnological pun. M. menardi and N. cellulanus live in caves and hence have as much claim to the epithet 'troglodyte' as any red-state Republican.

Having a BLAST

If you do what I tell you and go to the new Pharyngula, you're in for simply hours of good clean fun. PZ links to a somewhat snarky article, and that article tells you how to search the National Center for Biotechnology Information's Basic Local Alignment Search Tool (BLAST) database to learn for which proteins your name forms part of the sequence. On the basis of that protein, you may discover what sort of organism you really are! It's like the proteomic version of the Torah Code.

Here's what to do. Surf over to the BLAST search function for short, nearly-exact protein matches, type your name into the box, and hit BLAST! As every schoolchild (save perhaps those from Kansas) knows, proteins are built of amino acids. There are 20 of these, each corresponding to a letter of the Roman alphabet. (The six unused letters are B, J, O, U, X and Z. If you have such a letter in your name, you might wish to swap it out for an amino-acidically legitimate substitute -- I for J, LI for U, etc. If you don't, the BLAST search will simply ignore the letter.)

It turns out (on the basis of hypothetical protein K07E8.1) that I am the roundworm Caenorhabditis elegans:

(In fact, if you look closely at my right 'shoulder' you'll see a patch of the protein in question.)

As Andrew Brown will tell you, there are few animals as distinguished as C. elegans; so naturally I'm feeling very pleased with myself at the moment.

Pictures at a very old exhibition

If you've been looking for a website focusing on natural-history illustration, you've probably resigned yourself to disappointment.

After all, very few people in our degenerate times have the drawing and painting skills an illustrator needs. Of those few who have mastered the traditional media, fewer still have made the leap into digital technique.

And of that very select group, how many can add to their artistic skills the zoological and palaeontological knowledge a natural-history illustrator needs before he can even think about picking up a brush? I mean, you'd pretty much be limited to Carl Buell, wouldn't you, and Carl doesn't blog.

Until today, that is. Carl celebrates his 60th 59th birthday by unveiling Olduvai George, where you may begin to learn the secrets behind the wonderful animals that live in the upper left-hand corner of Pharyngula. Go wish Carl a happy birthday and enjoy the pictures he's sharing.

Bums, thrown out

The court's decision is still pending in the matter of 'intelligent design' creationists peddling their stuff to innocent schoolchildren in Dover, Pennsylvania. It doesn't look good for the creationists. Their prized tame scientist, Michael Behe, is putting a brave face on it, but he can't be feeling very happy about being forced to admit from the stand that, by the debased standards he must adopt in order to confer the status of 'scientific theory' on ID creationism, astrology is a scientific theory every bit as valid. As I say, the court will have the last word, but I'd be surprised to learn that its last word will please Behe, let alone those less fastidious about draping their creationism in a stolen lab-coat.

Meanwhile, whatever the court decides, the schoolchildren of Dover have already won an important victory. Democratic wins in two big state elections and the defeat of Ahnold's demagogic referenda in California may have grabbed this morning's American headlines. But as The Questionable Authority reports, on that same election day the people of Dover tossed the creationist members of their local schoolboard -- the ones responsible for the entire expensive and embarassing fiasco -- out on their ears. They have been replaced by candidates who insist that science teachers teach children science. Kudos especially to those of the candidates who, as I understand it, normally identify as Republicans but joined with Democrats to oust the troglodytes. It's good to know that not all Republicans are soliders in their party's war on science.

[TQA link via The Panda's Thumb. Cheers lads!]

Spineless, again

The Circus of the Spineless is coming to town once more, this month at Snail's Tales. Though the circus opens today, 31 October, Aydin is a few time zones behind me, so I'll update later with the precise URL. For the moment, you can just click on the link above to reach the front page.

A festival of creepy-crawlies -- what could be more appropriate for Hallowe'en? Or... emm... Reformation Day?

UPDATE: direct URL added.

Small Americans

Even though spiders creep Belle Waring out, she's game enough to link to a wee article in the New York Times about Norm Platnick, the doyen of spider systematics. Platnick is something of a BSD of the wider systematics world, actually: a founder of the Willi Hennig Society and member of the editorial board of Cladistics, he has had the honour of being savaged by Richard Dawkins (in The Blind Watchmaker) for being an insufficiently orthodox neo-Darwinian.

I left a comment at Belle's, of course, but have been told it is 'awaiting moderation', perhaps because I included a sales pitch for herbal viagra. While we wait for a CT moderator to happen along, let me tell you about a very nice book I have just received, the second cool spider-related thing to happen today. This would be Spiders of North America: An Identification Manual, edited by Darrell Ubick et al.

SoNA is a dichotomous key. That is, it helps you to identify an animal by making you walk down a road that forks repeatedly. At each forking, the key asks you whether or not your specimen has a given character. If yes, you branch off and follow further, ever narrower side-roads until you reach your destination, the identity of the animal. If no, you keep along the main road till you hit a forking that takes you off it. If there was a general key to all the spiders of Canada and the continental USA before SoNA, I do not know of it.

To European arachnologists, SoNA will sound (mutatis mutandis) a lot like Heimer & Nentwig's Spinnen Mitteleuropas, which was the standard key in this part of the world before it wandered out of print and into cyberspace (the successor to the old book is entirely online). SoNA offers something analogous to our comrades across the water. Unlike Heimer & Nentwig, alas, SoNA keys down only to generic level (though it does contain an extensive bibliography of guides to specific determination). It is superior to its European cousin in one important way, though. SoNA is chock full of beautiful diagnostic illustrations, most of them by Nadine Dupérré -- you can see a sample here. Unlike what you see in that sample, most of the illustrations in an arachnological key (and certainly the most important ones) are detailed pictures of tiny anatomical featuress (in most cases, not to put too fine a point on it, genitals). The illustrations in Heimer & Nentwig span a broad range of quality, with one end of that range being 'excellent' and the other end being, shall we say, something else. The illustrations in SoNA are uniformly excellent.

SoNA also contains lots of ancillary material. It's worth mentioning two bits specifically: an essay on spider phylogeny and classification by the Smithsonian's Jonathan Coddington, and an etymological guide to spiders' Linnaean binomial nomenclature (a must for these sad decadent times, in which schoolchildren are no longer universally force-fed Latin and Greek).

Spiders of North America will make a fab Christmas present for the arachnologist in your life. You can order it online from its publisher, the American Arachnological Society. Discounts if you belong to the club; you might also be able to cut yourself a good deal if you band together with others for a big mass order. That's what we did, 'we' in this case being people from the Arachnologische Gesellschaft eV (kudos to AraGes's entrepreneurial Martin Kreuels, BTW, for overcoming the collective action problem).

Thus does one refute Behe

'Cog Pseudonymous' of the Abstract Factory suggests some marvelous talking points for debating Intelligent Design creationists. Even better than the dialogue, though, are the props and stage directions.

HT: Steve Labonne in comments at CT, who in turn got it from PZ.

Vertebrae? No thanks!

There'll be no Friday arachnids for you this week, as I shall be swept up in the class struggle in Belgium (see next post). Here's some news that more than makes up for your loss, though: the Circus of the Spineless has pitched its tent and you've all been given free tickets. Ringmaster for the first performance is Tony of milkriverblog. After visiting the Circus, don't forget to have a look at the rest of the site: Tony's interests are highly eclectic (and include lots of lovely eukaryote cheesecake).

The Circus is another blogging 'carnival'. One of its spiritual forebears is, of course, PZ Myers's own child, the Tangled Bank. The Circus has a much more limited scope than the Bank -- it focuses solely on invertebrates. Still, given that the Arthropoda, Mollusca, Annelida & Co. make up the vast bulk of multicelled animals, that limitation shouldn't be too restricting. Step right up, and check your spine at the door.

And if you've written about invertebrates for your own site, or posted some interesting pictures of our non-chordate cousins, think about submitting a link to the Circus.

Friday arachnid blogging: not a spider

Well now we've all seen plenty of these creatures. Sometimes they are busily legging it through the undergrowth. Other times crowds of them are gathered on the shady side of a house, doing nothing much for hours on end.

One thing they aren't, though, is spiders. They are only spider relatives, and not terribly close ones either. They're opiliones, better known as harvestmen or daddy-long-legs; not to be confused with the spider Pholcus, which is also called daddy-long-legs, and certainly not to be confused with the crane fly, an insect that also shares this common name.

There's another, even cooler looking opilione beneath the fold; it's a very big picture, so if you have a slow connection you can make yourself a sandwich while it downloads.

Opiliones do have a rather spider-like habitus, or overall 'look'. Many (but by no means all) have the exaggeratedly long, thin legs that are the source of one of its common names. A few spiders have legs like that, but most don't. The really obvious difference between the two groups is that spiders have two main body sections, the cephalothorax and the abdomen, whilst opiliones appear to have only one. 'Appear', because they actually do have the same body division as spiders. Unlike in spiders, though, their two body sections are joined by a broad, fused connection rather than a dainty petiole, so they look like one big blob. If you look carefully at this one, though, you can see the division:

For all their spider-like appearance, though, opiliones seem to be as unrelated to spiders as one can be within the Arachnida. On the Tree of Life website, David Maddison divides the Arachnida into two basic groups. One contains, among other things, the spiders. Maddison places opiliones basal to the second group, whose most famous members are the scorpions. According to Maddison's cladogramme, opiliones (and scorpions etc.) are even less closely related to spiders than are the Acari (ticks and mites), a group universally accepted as Arachnida but (unlike opiliones) traditionally excluded from the discipline of arachnology. (Acari are simply too large a group, and morphologically/behaviourally too distinct from other arachnids; they get a whole discipline of their own, acarology.)

The other animals in the opiliones' subgroup are fierce indeed. Everybody knows about scorpions and their stings. Then there are the solfugids (wind-spiders or camel-spiders), which lack the venom of spiders or scorpions but have huge jaws that can easily slice into a human finger. Then there are the pseudoscorpions, which are unterrifying (to us) only because they are so tiny. Were we the size of an ant, we would find pseudoscorpions (which inject venom with their fingers and shoot silk out their jaws) significantly less cute.

Opiliones, though, are the pacifists of the Arachnida. 'Pacifist' in relative terms, of course, for the Arachnida are on the whole quite voracious predators. Some opiliones specialise in (for example) devouring snails. Most, though, will take what they can get. That could be something they kill, but it could also be something they scavenge, or even odd bits of decaying plant material. And two things make them outliers among all the Arachnida. They can include in their diet a bit of solid food (most Arachnida can only suck up the goop they have made by spewing digestive fluids onto or into their prey). And male opiliones have something that other arachnid males can only envy: a penis.

You'll find another opilione here No you won't; the 'other opilione' is the one just above there. Thanks to Aidan for the catch. The T6I proofreader who let that one get by is being flayed alive in our dungeons even now.

Friday arachnid (etc.) blogging: multi-legged mambo italiano

Before we get started, here's one jumping spider who has been waiting since May to appear on the web:

The stone railing you're looking at is on the Costiera amalfitana in southern Italy, which gives this post its theme. For the pictures below the fold are our holiday snaps from Italy (albeit farther north and from late August-early September). More than just spiders this time, today's FAB boasts stars from three great phyla, including our own. It's been a long time since I posted any Friday arachnids (as David Duff complains in comments to Tuesday's post), so as compensation you are getting a good many creatures today; those with slow connections might want to wait till they are at a computer with broadband access before going on.

We'll start with a spider, of course.

Now there's a pretty face. She shouldn't be hiding it bashfully behind her hand like that. (BTW, I have altered this photo by flipping it 180°. She's used to hanging upside down. You might not be, and turning the photo round will help you see her 'normally'.) We stared at each other for a while before I snapped the picture. That is, I stared at her; she stared at the tip of my nose, which would have been the bit of me closest to her.

It's an unanswered (and perhaps largely unanswerable) question whether and to what extent animals -- especially animals as little related to us and as relatively simple as spiders and other small arthropods -- are 'conscious'. Certainly they perceive, and some of their senses are so acute as to beggar belief. (Sight is not one of those senses, though, at least not in most spiders.) But do they conceive, and if so how?

If they are conscious at all, though, it's a safe bet spiders are not conscious of us as biological units. We're simply too big. If they are aware of a human, what they are aware of is the fingertip (or, all too often, the rapidly descending shoe sole) moving towards them. When your fingertip is in their range of vision, much of the rest of you is well beyond it. Perhaps it's good their brains are so tiny. Had they humanlike imagination, surely they'd be racked with terror at the thought of us, stupendously huge lumbering dangerous giants that we are. Bear that in mind next time you shrink back at a sudden flurry of tiny legs, shrieking 'Eeek! A spider!'

But all this philosophising is too much for our wee friend, who retires to her hideaway to consume a small moth she'd caught earlier.

This brute, by contrast, is far too big to be a meal for such a very small orbweaver:

He is a stag beetle of the genus Lucanus, a touch over 5cm in length. That's not especially impressive by stag-beetle standards; specimens of L. cervus (which is what I suspect this fellow is) can easily reach 7.5cm. Still, I am sure he is the biggest beetle I have ever picked up.

The beetle's thumping great jaws, by the way, are not for tearing gobbets of flesh from prey. These beetles feed by sipping daintily at tree-sap. The jaws are for males to use in rassling other males to see who gets the girl.

Though both belong to the great Phylum Arthropoda, the jointed-limbed animals, spiders and beetles aren't terribly close relatives. Compared with our next guest, though, they are kissing cousins. For that matter, even we are the beetle's kissing cousins by comparison.

This is a jellyfish, from the Phylum Cnidaria, the 'nettled ones' or, less poetically, stingers. And that is what they do, using nematocysts, specialised cells that are like a microscopic jack-in-the-box, only with a tiny venomous hypodermic harpoon inside instead of an evil-looking clown.

Cnidarians have no brains. Indeed, they have no head to keep one in. They are not bilaterally symmetrical like spiders, beetles and your own good self. Some of them live bizarre communal lives that make ants seem libertarian loners by comparison. Phylum Cnidaria includes animals most people have heard of, even though most will never encounter them: hydras; Portuguese men-of-war; corals; sea anemones; Australia's infamous box jelly, the 'sea wasp', with its unusually well-developed (for such a 'primitive' creature) eyes and its horrific sting. Best known of all cnidarians, though, and the ones you are most like to run across outside the aquarium, are the 'true' jellyfish, the Scyphozoa.

Lots of coasts are plagued by (often seasonal) jellyfish infestations. I have been fishing off Long Island, New York, where the water just below the surface was stuffed with jellies: at least one per cubic metre, each a bit smaller than your hand. I'm told that they don't often go all the way in to the shore, but can at some times of year, where they leave unlucky swimmers with an irritating but not particularly dangerous sting. The Costa degli Etruschi had its own jellyfish plague while we were there, though these stayed well away from the beach (they were at least a couple of hundred metres out, where we saw some swimming a little below the surface while we were kayaking). However, large numbers of dead or dying jellies were washed ashore. I don't know whether this is seasonal or had something to do with the weather. (Though the weather was fine much of the time, we did have some rain and high winds at night, and one enormous two-day storm at the beginning of our stay.) I didn't hear of anybody being stung, and the locals didn't seem concerned at the many meduse, as they are called in Italian.

Indeed I am not sure these jellyfish can sting. They ranged from about 18cm-24cm across the 'bell' and were mostly translucent, but for a dark blue ring round their rim. They look like Rhizostomae, which lack the long hairlike stinging tentacles of other jellies. In any event I accidentally brushed a bare foot against the tentacles of the one in the photo, and felt nothing unpleasant. I have read that all cnidarians have nematocysts; I do not know whether the Rhizostomae have lost theirs secondarily, whether their 'harpoons' are too small to sting a human, or whether the stingers of dead jellyfish simply don't work. (That last is a bit doubtful, actually, as some octopuses reportedly break off jellyfish tentacles to use as weapons.)

But hello, what's this?

There; do you see it? That brief white flash at the jelly's edge... and, quick as a wink, it's gone again.

It'll be back, though. It's a very small crab (crabs are crustaceans, which like insects and arachnids are one of the great arthropod subgroups). And it's nibbling at the dead jellyfish -- one of those 'circle of life' things. The crab was very cautious, and very fast. With its small size, it can obviously treat the saturated sand of the surface as a fluid, 'swimming' in it as easily as you or I would swim in a pool. A quick shear with the claws, and down it plunges, only to resurface a few seconds later for another bite.

It wasn't reckoning with me and my stick, though, and found itself flipped up the beach onto packed dry sand. It tried to scuttle sideways (as one does, if one is a crab) down to the water, so I flipped it again. This time it landed on its back and played dead. Interesting. I flipped it a few more times, and it always did the same: land right-way up, scuttle towards the water; land upside-down, lie still. I picked it up and took it home to the kids, pausing to dunk it in the water every hundred metres or so. My daughter was delighted:

The greenish-greyish mottling of her carapace is very effective camouflage in wet sand. The crab almost never needs this, though. We put it into a large clear plastic cup filled with seawater and some sand at the bottom. Straightaway it buried itself. All one could see (and then only if one knew where to look, and looked very carefully) were two tiny eyes, each like a grain of sand on a stalk.

Let's turn now to a 'crab' of a different sort, a Thomisid crab spider.

She's very tiny - about the size of a lower-case 'o' in this text, assuming you are looking at it in 1024 X 768 resolution. (I write 'she', BTW, though I cannot tell for sure. Given its tiny size, this spider is almost certainly immature. The pedipalp visible in the picture looks like a female's, but for all I know an early-instar male's might look much the same, gaining its characteristic 'boxing-glove' appearance only after further moults.) A crab spider is no more closely related to a true crab than is a great hairy tarantula, of course. But even though the photo can't recreate the spider's scuttling movements, it shows you how apt the popular name of these creatures is. Note how very small her chelicerae ('jaws') are. These are the two bits just beneath her 'face' and next to the visible pedipalp. The fangs at their ends are even tinier. Crab spiders are among those spiders that couldn't bite a human if they wanted to (most spiders never want to anyway). Her chelicerae even lack the jagged 'teeth' along their edges that many spiders' have, meaning she cannot chomp up her prey. She can only sip the liquefied innards out through the minuscule holes made by her fangs, leaving the prey's exoskeleton intact.

Here's another tiny and quite clearly immature spider. She is so young I am not even certain what sort she is.

From the general habitus and markings, though, I'd say she's probably an araneid (orbweaver). In any event, she is certainly... a SPIDER BABY!

Ted:      A spider baby?
Dougal:  It has the body of a spider but it's actually a baby.
Ted:      ... does it wear a nappy?
Dougal:  No...
Ted:      Well, does it have the head of a baby?
Dougal:  No.
Ted:      Then how do you know that it's not actually just a spider?
Dougal:  They keep it in a pram.

Erm... sorry, couldn't resist. At least you were spared the Tunnel of Goats. Anyway, to get an idea of the spider baby's scale, you can look at my daughter's string bracelets, which are the same as in the photo of the crab above (same daughter too, for that matter).

This great bruiser, though, is anything but dainty:

He's a male gnaphosid, or flat-bellied spider. Gnaphosids don't trap their prey in webs. They are hunters, but unlike the sharp-eyed salticids (jumping spiders) are mostly nocturnal, and their sight is hardly better than that of the hopelessly myopic orbweavers. Instead they hunt by feel, sensing vibrations around them and pulling down anything they stumble upon than cannot kill them first. Our specimen might possibly be immature, but if so is closer to maturity than the crab spider above. You can easily see the 'boxing gloves' at the ends of his pedipalps, even though he is not 'aroused'. (When he is, the 'gloves' will swell and expand to their full and, for each species, uniquely baroque shape.) He looks to be closely related to the Balearic gnaphosid who starred in an earlier FAB; perhaps even of the same species. Our lad would be about a centimetre in length, not counting legs or chelicerae, and like many gnaphosids is powerfully built. (The female from the earlier FAB would have made short work of him, though.)

Now here is a story with an unhappy ending (for at least one of the parties, anyway). You've probably seen insects like this one before:

It's an ensiferan, a grasshopper of the sort commonly called a 'katydid' and part of the same group that contains crickets. This one found its way to a table on our balcony. We'd just had coffee; the hopper found a couple of stray grains of sugar and lapped them up greedily. (I'd never heard of grasshoppers eating sugar before, but why not? They'll eat most anything; some of them even eat other grasshoppers.) Here she is scouting round for more. Hmmm, I thought, if she's hungry and has a sweet tooth... So I put her on a small plate and gave her a piece of one of the biscuits we'd been having with our coffee. Sure enough, she began chomping happily away. Then we went out and didn't return till the evening...

... and when we did return, there she was still, standing guard over her treasure-trove of biscuity goodness. She had gnawed away quite a visible chunk of it, too. A strange thing, though: there wasn't a trace of frass (if that is the correct technical term for grasshopper shit) to be seen. What happened the next day suggested an explanation for this curious absence.

That morning my daughter found the grasshopper prostrate on the balcony. She thought it was dead. It wasn't; at least not quite, not yet. She put it on the balcony's railing to have better light. The hopper just lay on its side, an antenna occasionally twitching. And then, after a while, a fat wee maggot emerged from the hopper's body; Alien in miniature. (Clearly the maggot wished to go elsewhere to pupate, as opposed to using the 'mummy' of its victim as a shelter, as may other parasitoids do.) Alas, a stiff breeze carried the maggot away before we could capture it. The same breeze also carried away the now-empty husk that had been the hopper.

Lots of people know that many wasps are parasitoids. And it's true that a great many hymenopterans are parasitoids, and that they account for the largest group of parasitoid insects. (Even bees, those vegetarians of the hymenopteran world, probably had parasitoid ancestors.) What lots of people don't know is that the Diptera -- flies, in other words -- account for most of the other known parasitoid insect species. And I think it was a fly that killed this hopper. There are tachinid flies that parasitise the katydid's cousins, crickets, attracted by their mating call. I shall have to look in Godfray to see whether there any suggestions about what insect killed our grasshopper, but I suppose we'll never know for certain.

Here is another katydid, so far as I know luckier than her relative:

She is running around at night. To my knowledge katydids are diurnal. But our balcony had a strange feature -- a large, bright light that could not be turned off. The light attracted many night insects (and things looking to eat them). But it also confused a lot of day insects caught in its glare come nightfall. This is likely what happened to the katydid in the picture.

They are very pretty, this species -- bright green with tiny red flecks; red eyes with, as you can see if you look closely, subtle brown stripes. Those black dots on the eyes aren't pupils, by the way. They're an optical illusion. The black dot you think you see is the patch of lenses on the insect's compound eye that you are looking straight down at. Those lenses you are seeing at an angle have their 'normal' appearance. As you shift the angle at which you view the insect, the black dot naturally shifts as well, creating an eerily pupil-like effect. This doesn't happen with all insects, but it does with many hoppers as well as with mantises.

While we're at it, let's have a closer look at the insect's face:

Do those mouth-parts remind you of little legs? They should, because that's more or less what they are. When we speak of an insect's or spider's mouth or jaws, we speak with perfect precision if we are thinking in terms of function. These bits do exactly the same job for a katydid or black widow that they do for us. But if we are thinking in terms of structure and origin, to speak of an insect's 'mouth' or a spider's 'jaws' is but broad analogy. Our jaws evolved from gill arches. Arthropod 'jaws' evolved from limbs. The postulated common ancestor of all arthropods was a segmented, wormlike creature whose segments bore appendages. As its descendants developed and diverged, some of these segments became legs, while others became 'mouth' parts. Still others became antennae or pedipalps or spinnerets or what have you. (To further complicate matters, other sorts of appendages served as 'gills' and, in lots of arthropods, still do.)

Our first arthropod today was a spider. Our last is a spider's worst nightmare:

It's a wasp, of course. And I am pretty sure she is a pompilid. (No idea what she is beyond that; those white bands on her antennae might be a clue for those who know more about hymenoptera than I do.) Pompilids are a group of wasps that hunt spiders. The pompilids include Pepsis, the famous 'tarantula hawk', an astoundingly big wasp of the American southwest that hunts even bigger tarantulas. (Pepsis, BTW, is reputed to have the most agonising sting of any insect. How do they get volunteers for those studies, I wonder?) Her cousin (as I suppose her to be) in the photo is much smaller, about 2.5cm in body length. I know little about wasps, but am guessing she is a pompilid based on general appearance, including her curly antennae and those long hind legs. I'm also guessing it based on this:

Here she is, invading a spider's (empty) sheltering-web. She didn't just stumble into it. She was walking around, seemingly purposefully, waving her antennae ('sniffing', as it were) and acted as though she knew just what she was doing. Alas for the wasp (but lucky for the owner of that sheltering-web), she was, like the katydid, the victim of our balcony-light. Being a pompilid wasp would seem to be a daylight job; her intended prey works nights, and was out on the job when she called.

The spider should be grateful for that. A pompilid paralyses a spider with a sting, then carries it off to provision the nest she digs for her larva. Sometimes she'll snip off the spider's legs first (the spider won't be using them anymore). Then she puts the spider into the nest and lays an egg on it. The larva hatches and slowly eats the spider alive. The spider is unable to move and can do nothing to escape its fate. I wondered up above whether spiders are conscious. Perhaps it is for the best if they are not.

Mind you, this wasp might be a sphecid rather than a pompilid. Not all sphecids hunt spiders, though this one (if sphecid she be) seems to. If she is a sphecid, her spider victims might have the consolation of being entombed alive in very prettily proportioned wee mudpots to await their doom, for the sphecids include the 'potter' wasps.

Our final animal is a member of Phylum Chordata, just like you. She's a toad, and though she is not a gorgeous jewel like some tropical rainforest frogs, by toad standards she is rather pretty.

She also has an interesting defence mechanism. When (for example) picked up by an excited child and held up for a parent to look at, the toad pisses. Pisses voluminously -- more piss than one would have thought a toad that size could ever possibly contain -- and all over the place, especially on the parent's feet, as any parent who happened to be wearing very flimsy open sandals at the time would be in a position to report.

So much for our Italian arachnids (etc.), then. I'm sure you'll agree with me that they are (like most things Italian) admirably attractive and stylish. I shall try to be a bit more regular in posting instalments of FAB but, for the time being, it's going to have to be the dour and stolid arachnids (etc.) of Germany.

Hearing they hear not, neither do they understand

Most Christians have no more problem with evolution than they do with gravity. Committed atheist PZ Myers frequently wishes more of them would take their literalist-fundamentalist coreligionists to task for turning the bible into a sort of poor man's kabbalah. Fred Clark must have heard PZ's heartfelt prayer.

(Be sure to read the comments as well -- there's even a cephalopod down there!)

ID: support from an unlikely quarter

From time to time I stop by Amitai Etzioni's website. And I generally find it most refreshing. Not that I am prepared to sign on to the Communitarian Manifesto, mind you (assuming there is such a thing). I would be hesitant to give Prof. Etzioni free rein to make laws. But I would be very pleased to have him as a neighbour, and even more pleased if a critical mass of people who share his values also lived in the neighbourhood.

But lately I've noticed a disturbing theme. Prof. Etzioni has taken to defending the teaching of 'intelligent design theory' in school science lessons.

UPDATE: In a new post, Prof. Etzioni takes a more nuanced view of ID in the schoolroom. (No permalinks; just go the main page.) He was replying primarily to an, emm, somewhat sharply-phrased post by PZ Myers (who does not suffer fools, or even those who give the appearance of possible foolishness, gladly). As Etzioni now puts it:

I asked why not use the comparison between evolution and intelligent design, in science classes, to show students the difference between a theory supported by scientific facts and those that are not? ... Students should be exposed to theories of both evolution and Intelligent Design and shown which one is scientifically supported. [Emph. supplied.]

That does put rather a different face on things. There's something to be said for showing the tykes the difference between good science and bad science (non-science, really). It's a pity Prof. Etzioni didn't make that clearer in his earlier posts. Still, I think he's wrong. When we teach children about astronomy, it doesn't hurt to mention in passing that people once thought the sun circled the earth. But given the amount of stuff to teach and the limited time in which to teach it, we probably shouldn't spend half the course on a detailed explication of heliogeocentrism [Doh!] before we proceed to dismantle it. One thing, though, is certain: Phillip Johnson, Michael Behe, William Dembski et al. are not going to very happy with including ID material in a school curriculum for the express purpose of its serving as the 'Don't' example. (It occurs to me that, should some American school district succeed in mandating 'equal time' for IDism, a clever teacher could use the lessons to immunise her charges against this and similar pseudoscience. But as I said, the time would better be spent teaching the children some real biology.)

[Original post continues under the fold.]

That's odd, because Prof. Etzioni is not a Christian at all, let alone a fundamentalist protestant or Roman Catholic. The former are traditionally the torchbearers of creationism. They have of late been joined by a number of conservative RCs -- which is strange, given that the RC church has not historically had big problems with the notion of evolution (and its current head has given evolutionary theory about as ringing an endorsement as one may fairly expect from a religious leader). Prof. Etzioni, though, is Jewish. I have no idea whether he is a particularly religious Jew, although the strapline of his website banner does suggest that he is at least more-or-less shomer shabbat. Still, Jews (religious or not) don't usually go in much for creationism. For creationism is the bastard child of literalist biblical fundamentalism, and that is a primarily Christian aberration.

I cannot tell whether Prof. Etzioni himself sees in creation the hand of an Intelligent Designer. Maybe not: to a large extent, his stance in favour of teaching ID seems a matter of wrongheaded fairmindedness: 'teach the controversy', etc. And, at first glance, that does indeed seem fair. After all, if there are two competing scientific ideas about why living things developed as they have done, should we not teach both ideas?

Certainly we should. ID, however, is not a competing scientific theory. It tries very hard to achieve a superficially sciency look-and-feel, but it is not science. I suppose we could call it a philosophical perspective. It rests on two broad principles: the Argument from Design (unsurprisingly enough) and the Argument from Personal Incredulity. The first of these found its classical expression in the work of William Paley, who gave us the evocative image of the Watchmaker. And (as arch-Darwinian Richard Dawkins once noted) it was a cogent argument in Paley's day; but alas for Paley, Darwin's subsequent proposals sapped it of its strength. The second argument essentially says: 'Something must be X, for I cannot for the life of me see how it could be other than X'. And this stance is fundamentally ascientific, indeed antiscientific. When a scientist cannot for the life of him see how something could be, he needs to tell himself, 'Well, I obviously have more work to do.' The IDist simply gives up.

Paley's argument from design has suffered from more than just the arrival of a new and better argument. Even if we leave evolution out of it, as we have learned more about various organisms we are faced with the stark fact that the Designer (assuming arguendo that there be one) is simply not very good at designing things. For evidence, you need look no farther than the nearest mirror. Indeed, you really don't even need a mirror. Especially if you are of a certain age, your back will speak to you eloquently of your imperfect design. Our spines, you see, do an adequate job of supporting our upright stance; but they are not well designed for this. If one accept the ID viewpoint, then one must give the Designer very low marks. But it makes perfect sense from an evolutionary perspective. When our remote ancestors decided it was time to stop dragging their knuckles and walk like men, natural selection had only their existing spines to work with; spines that had, till then, been honed over countless generations to do something other than walk upright. (Perhaps, when we have been around for a much, much longer time than we have been to date, our backs will finally have adapted to our lifestyle, and chiropractors and masseurs will be out of business. Until then, we must make do.) And there are more telling examples than our backaches, which are a rather trivial matter in the grand scheme of things. As I've noted before, Ken Miller calls the elephants and their relatives as witnesses against the Designer. These animals demonstrate pretty clearly that the Designer, if he exists, is extraordinarily fickle (and incompetent to boot).

The Argument from Personal Incredulity doesn't fare better. One of its champions is Michael Behe, a working scientist (at least, he used to be a working scientist) who accepts much of evolutionary theory, including the common descent of apes and humans. But he trips up against the notion of 'irreducible complexity'. There are some characters that are complex; if you knock out any of their component elements, they don't do what they are supposed to do. They are, as Behe would have it, 'irreducibly complex' and thus cannot have been shaped by evolution. (And, in a very narrow sense, he's right. Natural selection can't lay in a supply of characters that do nothing -- or are even deleterious -- against the off chance that they may combine with other characters to be evolved at some future date in order to do something worthwhile.) The problem for Behe's argument is that, even if he can't for the life of him see how complex biological characters can have evolved, others can. Once again, Ken Miller had a lot of fun at Behe's expense pointing out how the evolution of one of Behe's purportedly 'irreducibly complex' systems -- the clotting of blood in vertebrates -- was being successfully reduced in complexity even as Behe's book was in galley-proofs. Complexity isn't as irreducible as Behe thinks, it turns out. Let's say an important biological system has ten components, and won't function in the absence of any one of these ten. It's true that natural selection cannot 'plan in advance'. But it doesn't need to. If an organism has nine, or five, or even one of those components and that component does some other important job, it can be selected for. And if, a myriad generations later, another component crops up that can combine with the first to do a new important job, you can end up with a complexity of the sort that Behe cannot explain, but only gawp at in amazement, insisting it must be the work of the Designer. An important lesson of biology is that natural selection is conservative. It doesn't invent a dramatic macromutation where a bit of fine-tuning and jury-rigging will do. And it can only work with the materials that are to hand, so will often come up with new, complex characters that function adequately enough, even if (as your aching back will tell you) sometimes less than ideally.

Up to this point, we have been considering ID merely as an alternative explanation for the development of organisms. We haven't been considering it for what it really is: creationism dressed up in a lab coat. Prof. Etzioni asserts that ID is not creationism. He's wrong. It's true that IDism is nearly as incompatible with biblical-literalist 'young earth' creationism as is evolutionary theory. But if ID's proponents are relatively openminded creationists, they are creationists all the same. Prof. Etzioni might wish to have a look at Forrest & Gross's Creationism's Trojan Horse for a detailed examination of what the ID movement is really about. It is an attempt to inject religious instruction into the science classroom. In the United States, creationists learned long ago that teaching the biblical creation story in state schools as a 'religious truth' is impermissible. So they tarted it up as 'creation science' and started demanding equal time in science lessons. That didn't work either; ID is simply the latest attempt to repackage religious instruction as something else. (And it is interesting to note that this is a heavily American phenomenon. There is very little effort, even by religious conservatives, to see ID taught in European school science lessons. Of course, in many European countries, religious instruction is offered even in state schools. Perhaps European religious conservatives feel that this obviates the need to dilute the science taught in other lessons.)

Prof. Etzioni has, alas, also been taken in by some standard tropes of creationism. The evidence for evolution, he thinks, is 'weak'. On the contrary; evolution is, as a scientific theory, remarkably robust and creative. (And that's 'evolution', BTW, not 'Darwinism', as creationists like to call it. Darwin was a great scientist, but of course he got things wrong, and even missed a huge piece of the evolutionary puzzle. His contribution was great, but all he did was start the ball rolling. He is not a standard of orthodoxy against which all evolutionary theory must be measured; The Origin is not scripture. It is as contentious, and as wrong, to label evolutionary theory 'Darwinism' as it would be to call quantum physics 'Schrödingerism' or astronomy 'Keplerism'.) Etzioni thinks that 'no fact about evolution is the result of an experiment'. I think that by this he means, 'No hypothesis about evolution has been strengthened by experimentation', but even that is wrong. It's true that evolutionary biology is an historical science. We can't replay the Cambrian explosion under slightly altered circumstances to see how things would then turn out. But biologists can, and do, observe the historical record, draw inferences from it and make predictions accordingly. And those predictions can be checked, whether they be that whales once walked on land or that a moth would be found with a very strange proboscis that fits a certain orchid. What's more, given organisms with a sufficiently rapid reproductive cycle, scientists can (and do) run evolutionary experiments in the lab.

It's hard to fault the impulse of fairness that seems to motivate Prof. Etzioni's desire to see both ID and real biology taught in the schoolroom. But his fairness is misplaced. ID simply is not a 'competing scientific explanation'. There'd certainly be a place to consider ID in, say, a course on the history of biology, as an example of one of many wrong roads taken, together with (for example) Lamarckianism. (Of course, Lamarck was a much better and more important scientist than are the ID proponents, who have to date produced no actual scientific work.) But the place for that is not in the basic secondary-school science classroom. And schoolchildren should certainly not be presented with evolution and ID as equally plausible and meritorious theories and then invited to choose for themselves. If we're going to do that, we might as well also invite them to decide for themselves whether two and two make four, or rather five.

If Prof. Etzioni's schedule allows, he might wish to spend some time at The Panda's Thumb. He certainly should learn a bit more about IDism and the political programme of the ID movement before lending it the weight of his name.

Ernst Mayr RIP

I have just heard, through an arachnological mailing list, that the great biologist Ernst Mayr has died, aged 100.

It's sad that he has left us. But we may take some consolation in reflecting that he had a very long life, and a very long and fruitful career. Few of us can look back on such achievement.

And we may take some consolation in what he has left us. If, like me, you are not a specialist, you could spend a long time looking for a general introduction to evolutionary theory as good as Mayr's What Evolution Is, written at an age when most of us are dead and most of those who aren't are in their dotage. And if you find that whets your appetite, have a look at his earlier, seminal, Systematics and the Origin of Species From the Viewpoint of a Zoologist.

UPDATE: Down in the comments box, Sennoma has kindly provided a link to Michael Ruse's eloquent eulogy of Mayr. You've probably already read it, but if you haven't, go and do so -- and be sure to read the comments as well. (Cheers, Sennoma!)

Friday arachnid blogging (outsourced version)

Today I'll let somebody else do the FABing for a change. Dinesh's Spiderblog links to a page about the tetragnathid spider Pachygnatha zappa Bosmans & Bosselaers 1994. (The linked page, it appears, is part of a site devoted to organisms named for the late musician Frank Zappa.)

The names of Robert Bosmans and Jan Bosselaers are familiar to anybody in Europe (and probably far beyond) with an interest in arachnology. If you were wondering why they settled on Zappa as a namesake for this spider, they explain that it's not just that they happened to be listening to Gregory Peccary when they collected their specimen. No, they urge us; find yourself a female, flip her over and have a look at her belly. There you will see two dark markings that, together, look remarkably like Frank's moustache and soul-patch. (Are the spiders at all common, I wonder? The markings are clearly a miraculous sign, like Our Lady of the Grilled Cheese; but if anybody can scoop up a handful of these creatures in his garden, there's little chance of fetching a decent price on eBay.)

The page is well worth a visit. Not the same thing as reading the original description, of course. You'll find that in Zoologica Scripta 23(4), though this number is from long enough ago that it is not archived online, so you will not have the chance to pay Blackwell's lots of money for it and will have to go to the library instead (assuming you are one of those few benighted souls who do not maintain a full bound set of the Scripta at home). Still, the page does tell you a bit about the spider and has a couple of wonderfully clear drawings by Jan Bosselaers.

The second of these shows the underside of the female's belly. Go on, you'll see: B&B are right about that moustache.

Of even more interest is the first drawing, which shows the male of the species. You can tell he's a male by his pedipalps. As a faithful reader of FAB, you already know that these are (among other things) his organs of generation and normally look, to the naked eye, like tiny boxing gloves at the palps' ends. What you might not have known is that male spiders, like some men, are capable of 'getting wood'. When the spider is in the mood, the tips of his palps swell and distend. You don't really see it when the boxing gloves are in storage mode, but they comprise a number of sclerotised plates as well as erectile tissue. When expanded, the plates form a sort of complicated key that fits into the 'lock' of the female's epigynum. If you have never before had a close-up look at a randy spider, here is your chance.

And just abaft the palps you will notice the jaws (it would be hard to miss them). Technically, they're called chelicerae. These are the first in a series of paired appendages that develop in the larval spider. In the original chelicerates (the group to which the spiders belong), they were pincers, rather like a hand with a thumb and one finger. If you are ever lucky enough to find a horsehoe crab (not a crab at all but rather a large and 'primitive' marine chelicerate that turns up annually on beaches in, I believe, three parts of the world, including the northeastern seaboard of the United States), flip it over. (They might look fearsome, but they won't hurt you.) The first pair of appendages are chelicerae pretty much in the original form. If you live in the desert, maybe you've seen a solpugid (sun spider, camel spider). These are not spiders but their relatives, and they too have something like the 'original model' chelicerae, as you may see in this picture from Phillip Glogoza's solpugid website. Unlike spiders, they have no venom, but their jaws are large and very strong, so handle with care; they can give you quite a nasty nip if they feel threatened.

In spiders, by contrast, the chelicerae have been highly modified from the ancestral form. The chelicera is no longer a box-like 'hand' with two opposed pincers sticking out. One of the pincers has been lost altogether, and the other is bent back (often fitting into a groove in the cheliceral base, or what's left of the 'hand'). The derived pincer is now a fang; a hypodermic syringe, really, for injecting prey with venom. In some spiders, the fang is also used to 'chew' the prey by mashing it up against the base of the chelicera, which may even have spiny 'teeth' for better mashing.

P. zappa and its pachygnathid relatives are, emphatically, spiders of this sort. Their jaws are ridiculously enlarged. They tend not to be as long as those of some of their fellow Tetragnathidae, but they are much stouter. And hence their generic name, 'Pachygnatha', from the Greek for 'thick-jawed'.

An ID proponent with an intelligent designer?

Via Pharyngula comes this wee gem from the letters page of the Centre Daily, a newspaper of State College, Pennsylvania (home of Penn State University).

The letter-writer, one Richard S. Brown, purports to be a 'manufacturer and part-time tree farmer'. His manufacturing and tree-farming, though, apparently leave him time to pen ill-informed screeds against 'naturalist evolution'. Brown's letter is even more incomprehensible than the usual run of IDist stuff. So much so, in fact, that PZ Myers suspects 'Brown' might really be Michael Bérubé having a bit of a leg-pull.

In the end, PZ concludes that this probably isn't Bérubé. Maybe he's right. After all, Brown's letter is a game effort, but undoubtedly real IDists can be even funnier. For instance, check out this boffo piece by Phyllis Schlafly. Schlafly understands almost nothing about the evolutionary theory she attacks. That's not unusual. But it's clear that she also understands almost nothing about the ID theory she supports. (She seems to think that 'design' is meant in the aesthetic sense.) Steve Reuland deftly gutted Ms Schlafly at The Panda's Thumb, BTW, but really, her own hand was quite enough for the job.

Brown's letter can't quite match Schlafly. But still, as these things go, it's pretty good. If Bérubé really is behind it, he is worthy to be mentioned in the same breath with 'Albert Simpson', letter-writer extraordinaire to the John O'Groat Journal (an obscure master of the letter-writing art, concededly, but a master nonpareil for all that).

Christmas Eve arachnid blogging (and for once it's not a spider)

It is spiders that give the class Arachnida its name (and spiders in turn got their Greek name from Arachne, whose skill at weaving was, alas, matched by her insolence). But there's more to arachnids than just spiders. We've all heard of scorpions, we've all seen harvestmen (though some people mistakenly think them a sort of spider). But there are also orders in the class that relatively few people know. As a special gift, we'll have a look at one of them today.

Meet Allochernes wideri, a pseudoscorpion:

As their name suggests, pseudoscorpions are a lot like real scorpions, only more pseudo. Also, they're tiny. The A. wideri above is just a hair over 2mm. Some pseudoscorpions hitch rides by clinging to the knees of flies.

Pseudoscorpions are known for living in old books, and perhaps you have seen one while perusing your incunabula. I don't own any incunabula myself, and anyway books are not where most of these animals live. If you want to find one, you'd be better off scouring a bird's nest, or some leaf litter, or (in the case of A. wideri) looking beneath the bark of a fallen tree.

These are fascinating creatures, and it is invidious to describe them merely as miniature scorpions devoid of a scorpion's venomous sting. (It is true, though, that within the class Arachnida they are pretty closely related to scorpions, whilst only distantly related to spiders.) For one thing, pseudoscorpions do have venom. They inject it with those alarming-looking claws. You needn't worry about a pseudoscorpion's venom, though; they are far too small to harm you. I have never heard of a pseudoscorpion managing successfully to envenomate a human, much less of a human reacting to the venom. The claws are obviously homologous with the claws of scorpions, and less obviously with the pedipalps of spiders. (The palps are 'mini-legs' just in front of a spider's foremost 'real' legs. Spiders use their palps like hands; males also use them to inseminate their mates.) Like spiders, pseudoscorpions use silk. Unlike spiders, whose silk glands are at the back end, pseudoscorpions emit silk through their 'jaws' (chelicerae, which are in origin the first pair of appendages). They don't make webs like a spider's, but they do weave little tents and sleeping-bags.

Some pseudoscorpions are social. That is, they live in cooperating groups. They are not what zoologists call 'eusocial', like ants and some wasps and bees. In eusocial organisms, the members of an entire nest (or what the Germans charmingly call a Volk, or 'people') subordinate their own reproduction to that of their queen. No, pseudoscorpions have managed to attain only the same level of sociality that, for example, we humans have. (Among mammals, naked mole-rats are the sole known true eusocials). In the first volume of William Hamilton's collected papers, there is a not very high-quality but nonetheless exciting photo of a group of pseudoscorpions hunting an ant. They nip in to paralyse their large and dangerous prey by pinching its extremities; when the ant is subdued, the pseudoscorpions' young will be the first to feed.

Here's another glimpse of our wee friend:

Now, if you'd like to see some truly excellent photos of pseudoscorpions by somebody who (unlike me) has top-grade equipment and knows how to use it, drop in at the American Arachnological Society and have a look at Hans Henderickx's pictures.

Friday arachnid blogging; or, The Body of an American

While in America last summer I saw a number of spiders, many of them unfamiliar to me. One of them was this impressive jumping spider:

Her jumping days, alas, are over. I killed her with kindness, and I bitterly regret it. Now, I've killed a lot of spiders in my day, and don't regret doing so at all. When I collect a spider, I kill it quickly in alcohol (which is also what the specimens are stored in; you cannot pin a spider to a card as you would an insect). I don't much like the fact that they die, but I do not feel bad about killing them so that I can later study them.

But my daughter was with me the day we found this spider (in New York, BTW). She loves nature in general and spiders in particular, but is unhappy to see them dropped into alcohol, and she successfully pleaded for this one's life. Okay, I thought, I'll just immobilise her for a bit (the spider, not my daughter) so I can take some close-up photos, then set her on her merry jumping way. Spiders being cold-blooded creatures, you can make them groggy by making them cold. So I put her into a freezer for a few minutes. Then out into to the sunlight for the photo op, and I fully expected that, as she warmed up, she'd stretch her legs, yawn, and scuttle off. It was not to be; she was fated to hold that pose forever. As I said, it doesn't bother me to kill a spider that I mean to collect; but it bothers me quite a bit to have killed through stupidity one that I meant to release. Next time I'll use the refrigerator instead.

But there remained the question: what sort of jumping spider was she? I had never seen anything like her.

For one thing, she was (by jumping spider standards) huge. Most are tiny to midrange, but she was immense. (Relatively speaking; she could still sit comfortably on your thumbnail.) And, though she was for the most part dark and dull, look at those amazing metallic chelicerae!

When you want to identify a spider (or other animal) you've never seen before, what you do is sit down with a dichotomous key. If you've never seen one of these, they work a bit like those 'Choose Your Own Adventure!' books. Only, instead of working your way towards an ending, happy or otherwise, you are working your way towards the taxon to which your specimen belongs. Here's a simplified example:

   Eight legs, two main body parts, fangs ......... 1
   Other................................................. 2

If you go to 1, you will be presented with another series of dichotomies that you can follow, ideally, all the way down to Spiderus ickyus, or whatever. (Or, if your specimen didn't match the description for 1, you'd go to 2, and follow the chain of dichotomies there, until you eventually learn that your specimen is a vampire bat, or a sea-slug, or a blue whale.)

Now, determining a jumping spider can be a daunting thing. The Salticidae, as they are formally known, are a species-rich family. Indeed, there is none richer in the spider world. At last count (according to Norman Platnick's World Spider Catalog) there were 5,001 species of salticids, in 544 genera. Still, given my spider's large size and gleaming 'jaws', I'd hoped the narrowing-down would go quickly.

It didn't. In fact, it didn't go anywhere at all. The key I usually use, Spinnen Mitteleuropas, is excellent (there's even an online version). 'Mitteleuropa' means something different in spidering terms than it does politically, but still, it's a reasonably big swath of land. And nowhere in it, it seems, does my spider exist. A somewhat less systematically rigourous web search (looking for references like 'metallic fangs' and 'big') soon suggested, though, that my spider belongs to the salticid genus Phidippus. And a look at some salticid websites soon turned up pictures that confirmed as much. (P. audax seems a likely candidate.)

Here's the thing, though: Phidippus is an American spider genus. According to Platnick, its species are found in North and South America, with the overwhelming majority north of the Panama canal; indeed, most are in the United States. (Platnick also lists a few species on the Indian subcontinent, but notes that these are probably misplaced in the genus.)

Wayne Maddison, who contributed the salticid bits of the Tree of Life web project (which is where you'll find the photos of P. audax I linked to above), places Phidippus among the Dendryphantinae, salticids that are phylogenetically distant from the ancestral form. Most of these are New World spiders; Eris and Dendryphantes are the only two genera I've heard of in my insular European world. (Incidentally, you shouldn't assume that Dendryphantes is ancestral to the clade. Maddison's cladogramme shows where the Dendryphantinae fit in among the salticids, but not how the dendryphantines relate to each other. That the genus gave the subfamily its name may simply reflect the fact that European naturalists described the local members before anybody described their New World cousins.) I'd be very interested to learn more about what systematists think of dendryphantine phylogeny, and why lots of species of a couple of genera ended up in the Old World while most of their relatives are in the New.

Maddison, BTW, has an extremely impressive jumping spider website. By its title, it deals only with American salticids from north of Mexico, but don't let that fool you. Be sure to visit the gallery, which includes a virtual tour through a jumping spider. This is an excellent introduction to spider anatomy in general and to salticids in particular. Don't miss the chapter on their eyes, a part of the jumping spider that (rightly) so fascinates everybody who takes a look at these charming little animals.

Friday arachnid blogging: Spot the gnaphosid

To warm you up on these cold wintry days, here is a spider from the sunny Mediterranean. She is Poecilochroa, probably P. variana.
 

Members of this genus can be found in most of Europe, bar the northernmost bits and the British Isles. The two commonest species are P. variana and P. conspicua. If you're a real pro, you'll tell them apart by peering at their genitals through a microscope. The females of most spiders have something called an epigynum. This is a sclerotised plate covering the female genital opening. It corresponds to the complicated tips of the male's pedipalps, and together they work like lock-and-key. P. variana's epigynum is flat and very lightly sclerotised, not much more than a slit; by contrast, P. conspicua's is heavy and arrow-shaped. If you're at all thrilled by the thought of spider genitalia, you can see drawings of Poecilochroa epigyna and palpal tips at the Spinnen Mitteleuropas website (the upper reaches of this site exist in an English version, but when you get down to species level, some pages, including this one, haven't yet been translated from the original German).

I'm not a real pro, though, and I don't have a decent microscope. (My dream model, from Zeiss, costs over €20,000 with all bells and whistles, and even a decent used binocular dissecting scope from the old East German Zeiss would likely set me back nearly a thousand.) What I do have is a 'microscope' that looks like a fat fountain pen. Its magnifying powers are adequate for looking at most bits of all but very small spiders, but it's extremely hard to use. So I spared my spider the embarassment of a genital examination, and instead decided she is P. variana because she has that white spot at the end of her opisthosoma (abdomen); P. conspicua doesn't.

That's a quick and dirty method of determination, of course, and it could well be wrong. Though P. variana and P. conspicua are common and widespread in Europe, Fauna Ibérica records four other species of Poecilochroa in Spain. I don't know which of these live in the Balears (the spider above is from Formentera), but P. albomaculata, at least, is recorded in Corsica as well as Spain so it's reasonable to think you can find them on an island in between. And the white spot on the prosoma (i.e., the front bit, sometimes called the 'cephalothorax'; the white spot covers the 'head' bit, distinguishing it from the 'thorax' bit) does look like the sort of thing that might have prompted the epithet 'albomaculata'. But I have access to neither pictures nor diagnostic drawings of P. albomaculata (or, for that matter, the other Poecilochroa spp. recorded in Spain), so I am going to have to go with variana as a tentative best guess. (Though I'd welcome correction from any Iberian arachnologists who might happen upon this post).

But maybe you're not so interested in spiders that you care which species of Poecilochroa this is. Even so, when a spider crosses your path, you've probably found yourself wondering what kind it is. Focusing on the slightly bigger picture, the spider above is a gnaphosid. The Gnaphosidae are a family of medium-sized to fairly biggish spiders. They are hunters, not web-spinners. They tend to be solidly built, with heavy armour on their prosoma and legs; and, though our Poecilochroa is attractively patterned, many gnaphosids are drab. (An earlier edition of FAB showed a typical representative of the family.) Drab or not, though, there's an easy way to tell whether what you are looking at is a gnaphosid. And you won't even need a microscope (though with smaller examples you might want a magnifying glass). And that way is to look at their bums.

A spider's silk comes out of little nozzle-like things called spinnerets. Originally, these were appendages much like legs. Just as evolution has modified appendages up front into the spider's 'jaws' (and its pedipalps, whose derivation is plain to see), it has modified appendages just behind the legs into spinnerets. (In most spiders, these appendages have migrated bumwards, but in a few 'primitive' sorts you'll still find them at the bottom of the belly just behind the legs.) And the number, position and/or shape of the spinnerets can be an important clue for determining spiders at taxa above species.

A gnaphosid's spinnerets are large and cylindrical. Here, let's have a look:

And here's an even closer look. I must apologise for the fuzziness of the image, but this is a tiny piece cropped from a much larger photo, and we are running up hard against the limits of 72 pixels/inch resolution. Squint a bit, if that helps. (And try to avoid thinking that you could squeeze silk from them as you'd squeeze milk from a cow's similar-looking teats. Your hands are much too big; and if they weren't, well -- gnaphosids are less docile than cows.) Now, what's so important about those cylindrical spinnerets? Well, there is another large family of similarly-sized, similarly-shaped, ground-dwelling, mostly drab hunting spiders called the Clubionidae. The quickest way to tell gnaphosids from clubionids is to look at the spinnerets. Whilst the gnaphosid's are cylindrical, the clubionid's are long tapering cones. There are other visual clues that differentiate the two families -- e.g., the eye pattern and the look of the chelicerae ('fangs') -- but none is quicker, easier or as sure as the shape of the spinnerets.

Two questions for scientists

I have nothing to tell you at the moment. But I do have something to ask you, if you happen to have the scientific knowledge to answer my questions. The first question involves physics and arises from cookery. The second involves entomology and arises solely from my morbid curiosity.

1. The Case of the Catastrophically Collapsing Alioli

A few weeks ago I was cooking for guests. Spanish and Catalan dishes were on the menu, so of course I thought to serve alioli among the starters. If you don't know what this is, it is a garlic mayonnaise; the southern French make something very similar with an almost identical name. Indeed, I was cheating: the recipe I followed was for the Provençal aïoli rather than the Iberian alioli. You will find a recipe (not the one I used) here.

I followed the recipe precisely. I made the stuff in a mixer. This is no shoddy 1970s Soviet mixer either; it is a muscular and aggressive KitchenAid machine from America. I very slowly poured a thin stream of olive oil through the hole at the top. The alioli thickened nicely; so much so that the machine's motor began to struggle audibly. But just as I had poured in almost all the oil the recipe demands, the alioli collapsed. Literally: it fell in on itself, all thickness gone. It had, in the space of a moment, become a liquid only as thick as the oil itself had been.

As a a would-be alioli maker, I was deeply annoyed. (It was only a minor annoyance; the jamón pata negra and olives, not to mention a pretty good manzanilla, kept the beasts peaceful until the second course.) As an objective observer, though, I was fascinated. This was the coolest Strange Food Phenomenon I had seen since that one time I opened a very cold bottle of Coke only to watch it freeze visibly, as though caught in that awful ice storm from The Day After Tomorrow. (In that case, I presume the sudden release of pressure upon opening the bottle was sufficient to make the liquid's temperature drop below freezing.) But as for the collapsing alioli: what food physicist can tell me why this happened?

2. Alien vs. Caterpillar

We've all seen caterpillars that look as though they've been festooned with rice. (If you haven't, look here.)

That's not rice. These caterpillars have been parasitised by braconid wasps. Braconids are koinobiont endoparasitoids. Parasitoids are insects -- mostly wasps; a surprising number of flies; and a few representatives of other groups -- that develop in or on other arthropods, usually other insects (though spiders are often victims as well). Unlike parasites proper, parasitoids almost invariably kill their hosts. The hosts of koinobionts continue to live and develop for a time after parasitisation. (Idiobionts, by contrast, permanently paralyse their victims when the egg is laid.) Endoparasitoids develop inside the bodies of their hosts (ectoparasitoids, obviously, do so on the outside, with a bit stuck into their host for feeding). The aggressive creatures in the Alien series, in other words, are classic koinobiont endoparasitoids, as HCJ Godfray points out in his magisterial Parasitoids.

Now you are no doubt cocking a sceptical brow and thinking, If braconids are endoparasitoids, what's with the rice-like stuff? Well, those are cocoons, and that brings me to my question. Braconids develop inside the caterpillar, drinking its haemolymph ('blood', more or less). They avoid doing fatal damage, because this would be fatal to them as well. When they have done growing as larvae, they emerge through their host's skin (not a pretty sight), spin cocoons and pupate. The caterpillar goes on munching leaves, seemingly none the worse for wear.

It is, though. In fact, it is doomed. When the imagines (adult wasps) are ready to emerge, the caterpillar stops eating, goes off some place quiet so its killers can eclose in peace, and dies shortly thereafter. What bothers me is that I can't for the life of me figure out why.

Some parasitoids, just before emerging, go ahead and devour all the vital organs they have hitherto been careful to spare. So far as I know, though, braconids just drink haemolymph. And at the time they stop doing so, their host is still healthy, at least to outward appearance. I am not aware that the wasps continue to feed while in pupal form. I could understand that, when they have opened their cocoons and flown off, the holes from which they exited the host might be exposed, subjecting the caterpillar to dessication or infection -- but from that I'd expect a death rate that, while perhaps high, was not 100%. And yet they always die. Why? What is it that kills them, seeing that the parasitoids' feeding activities themselves apparently do not?

Friday arachnid blogging; or, Had we but web enough, and time

Are you a shy man? Can't bring yourself to chat up that hot babe at the bar? If so, take comfort in the thought that you are not alone. Even among your very distant spider cousins there are those who cannot screw their courage to the sticking point.

Late one August night in New York I saw a female spider sitting in the middle of her large orb web. She looked like a member of the genus Araneus, but apparently of a North American species (A. cavaticus, perhaps?) that is not familiar to me.

She wasn't doing much. She was just sitting there, as araneids are wont to do when there is no prey on their web. But another spider was doing something.

It was a male, cautiously inching his way down one of the structural lines supporting the web. So far as I know araneids do not attack their conspecifics on their webs; he can only have been after one thing. Down he crawled, until he reached the outermost of the web's spiral lines. Here he paused. Then, carefully, he began gently plucking the strand. He'd pluck a few times, then wait; pluck, and wait. He was acting sensibly. Most spiders are solitary, and aggressive. In many cases, a close encounter between two spiders, even of the same species, ends with a single well-fed spider. And this male, as is often the case in the spider world, was significantly smaller than his belle. Like insects, spiders are believed to use pheromones in their mating behaviour; that's probably how he identified the female's web when he happened across its anchoring line in the tree above. But as the lovers move to their tryst, visual or (in the case of the weak-eyed araneids) tactile signals take over. By making stereotyped plucking movements at the edge of the web, the male was saying, 'Honey, I'm home! And not for dinner!'

His plucking did not seem to elicit much response from the female, though. I thought I saw her, very occasionally, make a very slight movement with her first and second left legs. Was she sending a signal back? Her movements were so faint that I cannot be sure she was, but if so, the message was apparently not 'come hither'. After a few minutes, the male turned round and shimmied back up the line to the tree. After about twenty minutes he returned and began the process again. The slow descent down the web's structural line; the plucking at the outer edge of the spiral; and then the retreat to the tree. I watched him do this five times over the course of two hours. ('Have you nothing better to do with your time?' you are no doubt asking. In fact at that moment I had not. My camera is not at its best under those circumstances, as you can see readily enough from the photos, but I was prepared to invest a bit of time on the chance I'd capture some Spider Porn.)

But two hours was time enough, and eventually I went off to bed. I do not know whether the female's suitor eventually persuaded her to give it up. The sad fact, though, is that it wouldn't have mattered if he had. Spiders of this sort spend their days in a hiding place. The female in question, as it turns out, had chosen a secluded spot under the rim of an outdoor gas grill. The next day, alas, saw things grilled. The spider was not consumed in the flames (she was well away from them), but the heat was sufficient to kill her. The grill's a fine and private place, but none, I think, do there embrace.

Flesh of my (or perhaps somebody else's) flesh

Harry Brighouse notes that we tend to accept as axiomatic that people have an interest in having children to whom they are biologically related. He wonders, though: do we really, when you come right down to it? Can one meaningfully say (or deny) that people have an interest in rearing those biologically related to them?

I suppose it depends on what you mean by 'interest'. Are you asking, do people have some underlying right to raise biologically-related children (assuming they manage to produce some) and that, under normal circumstances, the state should not force them to raise other people's children, or cart their children away to be raised by somebody else? They have that sort of 'interest' if the law says they have it. If, on the other hand, by 'interest' you mean that they most people have more or less strong feelings on the matter, then I think one is not jumping off a terribly high bridge in asserting as much.

Pace Daniel Davies's exhortation of a Dawkinsian off-fucking in the comments thread, on one level people clearly do have an interest in biologically-related children. This is, however, merely the level at which we are lumbering robots etc. etc. etc. (to stick with Dawkins), the level at which one would would lay down one's life for two siblings or four cousins. Our genes, should one wish to work with Dawkins's metaphor of genes as 'selfish', clearly do have an interest in our expending effort and resources only on offspring that have, in fact, really sprung off from us.

We are not our genes, though. Still, and slag off EvPsych as much as you like (and a good deal of the slagging may be justified), it shouldn't be surprising that behaviours catering to this interest of our genes would be fruitful and multiply. Sexual jealousy; social codes that frown on adultery; the fact that biological fathers are statistically less likely to murder their children than stepfathers -- it would be overly reductionist to say that these are 'all in the genes', but at the same time, one can see how genes encouraging that sort of thing would have an advantage over genes that don't. And that doesn't go only for humans. Cuckoos and their hosts are locked in an evolutionary arms race, and for obvious reasons. That most people would have a strong preference to raise biologically-related children is eminently understandable. And EvPsych offers, I think, some valuable insight into that understanding.

Genes don't really have 'interests', though; people do. But what do we mean by saying somebody has an 'interest' in rearing a biologically-related child? Perhaps no more than this: it's important to them, and one can see why. Doubtless there are evolutionary factors at play in this, but surely it's crude to say 'People's interest in raising their own children is nothing more than the selfish genes at work.'

In the same way, there are many parents who adopt children. At one level, it's justifiable to postulate that 'our genes' inculcate in us a desire for children, and adopting children allows (often, but not always) childless people to respond to that desire. Very true as far as it goes; but it's crude to reduce the generosity of adoptive parents to the work of a different set of selfish genes.

The insights of evolutionary biology can be very true and very informative, but they should not be made to do duty they were never intended for. On a trivial level, it's precisely true to state that adoptive children (at least, of otherwise fertile parents) are nest parasites. But that doesn't tell us anything worth knowing; and if one proceeds from that statement to the conclusion that adoption is 'about' nest-parasitism, it's not merely trivial but grotesque, absurd and obscene.

Having duly noted evolutionary insights, we can pretty much dismiss them from consideration in this discussion. They can go a fair way to explaining why most people want to raise their own biological children, and why many people are happy to raise somebody's else. But they don't tell us what these interests mean. But nor do I think we need much in the way of extensive research to get comfortable asserting that people have such interests (or desires, if you prefer that term).

Friday arachnid blogging: hidden beauty

As I mentioned last week, here is a spider my daughter found and brought to me for photographing. She made me set it free after our session, though, so the spider escaped the fate of so many of its fellows. But that, of course, meant that I couldn't identify it by patiently walking down the bifurcating lanes of a dichotomous key.

What I could do was make some guesses as to what she might be, do a Google image search and see whether I got anything likely-looking. And I did; the spider is of the genus Leucauge, the orchard spiders, from the family of Tetragnathidae, the big-jawed orb-weavers. I was rather excited to learn this, as to the best of my knowledge there are no Leucauge where I live. At any rate I had never seen one before, and she was a nice little reward for visiting America. And I'm glad I wasn't allowed to keep her. She was very small, and I didn't notice how pretty she was until I saw the blown-up photo on my monitor. Look at her bright green legs, her flashes of black and yellow, and the glittering silver-white of her abdomen. All that would doubtless have faded in alcohol. It is usually obscure bodily structures that distinguish one group of spiders from their relatives -- with Leucauge, it is the presence of certain hairs on the leg -- rather than colours or patterns. But it is those patterns and colours that make some spiders so beautiful.

It's rare that one can make a good species identification on the basis of a photograph. (The process of determining down to species level usually requires a microscope and is highly embarassing to the spider.) On top of that the spider in the picture is a juvenile. As one normally identifies species on the basis of the adult genitals¹, this spider is then not even in principle identifiable to species level. Certainly the American Museum of Natural History won't venture below genus in identifying this very similar spider. For all that, though, there is some chance the spider is L. venusta, as that seems to be the most common Leucauge in those parts.

¹ You might be surprised, though, at what constitutes 'genitals' if you are a spider. For females, it's something like the lock on a chastity belt. For males, it's the hands.

Friday arachnid blogging: sometimes natura does facit saltum...

...just not in the way Richard Goldschmidt meant. Here is a Salticid, or jumping spider, about to do just that.

I will tell you freely that I do not know what she is, other than that she is a jumping spider. I photographed her prowling on a window ledge in Long Island, New York, and didn't capture her to key her out. And I am not very familiar with jumping spiders; I can't tell her genus at a glance as some people could. (For some reason I rarely see jumping spiders where I live, other than the ubiquitous Salticus scenicus or zebra spider.) I encourage anybody who can make an educated guess as to her genus to let me know in the comments or by email; species identification is almost always too much to hope for from a photo.

Many people, even those who generally dislike spiders, find jumping spiders rather charming. It's easy to see why. Most of them are small and not remotely threatening. Many are brilliantly, beautifully coloured. And, most important of all, they have big 'foreheads', stubby limbs and a great huge round pair of eyes. That's right, they have roughly the same proportions compared with other spiders that human babies have compared with adults. It sounds ludicrous, but I truly believe that jumping spiders can trigger the same feelings (though in a much fainter way) that the neotenous features of babies produce in most of us. It's not that anybody is going to feel an urge to chuck a Salticid under the 'chin' and say gitchy-gitchy-goo, but they are certainly the cuddliness champion of the spider race.

Quite apart from that, they are fascinating animals. They're impressive jumpers (as you'd guess from their name). Unlike most other spiders, they have keen eyesight (as you'd guess from a look at their eyes). And they are very clever as spiders go. One jumping spider, the bizarre Portia that specialises in attacking other spiders (even in their own webs), has demonstrated levels of technical adaptability, spatial memory and problem-solving ability impressive in an animal whose 'brain' is the size of a pinhead.

Over the next couple of weeks I'll show you some other spiders I found the same day and can't very readily identify. One my daughter caught and let me photograph, but she made me release it after that. Another was a second Salticid, but this one was (by Salticid standards) a mambo-jambo whopper of a spider -- most jumping spiders are small. I wanted to release that one as well (I must have been feeling soft-hearted that day) but fate intervened. In order to make her quiescent for some close-up photography I put her in the freezer for a few minutes. It must have been a few minutes too many, for she did not revive when I warmed her in the sun. (I'll try the refrigerator next time.) I truly felt bad about that. I have killed many a spider in my time in order to collect them; but I dislike the thought of killing a spider unintentionally and, let's be honest, through stupidity. But at least I now have her in a bottle of alcohol and can try to run her through a dichotomous key. It's quite likely her species isn't found in the region covered by the key, but by the time I put up her picture I hope to have at least her genus pegged.

Oh, and I'll also show you another example of sexual frustration in the arachnid world.

An inordinate fondness for your garden plants

You might be used to seeing spiders on this site, but I thought for once I'd show something with rather fewer legs. Here, then, is Popillia japonica, the Japanese beetle. Though I didn't find this one in Japan, I did find it in the Orient -- in the original sense of the word: the east (or, in the word's literal sense, land of the rising sun). That it is the east of the United States I refer to is a mere quibble.

Pretty though she is, she is also a menace. As an adult, she chomps plants insatiably (as she is doing in the picture). As a grub, she damages plants' roots. And in the United States, she's hard to stop. Back in Japan she had any number of natural enemies, but America isn't the land of golden opportunities for Homo sapiens alone.

I have no real reasons for posting this picture, beyond these:

1) Go on, admit it: she is beautiful, isn't she?

2) She's a classic example of an invasive species: an organism that is transported outside its natural range (usually through human ineptitude) to a new place where it can wreak havoc. So this gives me the opportunity to link to Jennifer Forman Orth's Invasive Species Weblog. If you are at all interested in ecology and want to learn about a fascinating but serious problem, this is the place to go.

Mysteries of the web

Fellow AFOEer Nick Barlow has decided to reap the vast financial rewards of blogging by selling ad space to Google on What You Can Get Away With. As we have all heard, it is Google's fiendishly clever algorithms that optimise the results of its searches and have made the firm worth an estimated 750 squintillion gazillion dollars. But what algorithms can they possibly be using for their ads?

The Google ads column on Nick's site, you see, begins today with not one but two ads for traps that catch the dread brown recluse spider. (The traps are also good, we're told, for the hobo spider and the black widow, though as widows don't wander round much I have to question that last claim.) Whilst I am sure that this company's fine product is just the thing for ridding one's house of the bloodthirsty and lethal recluse, I confess puzzlement at the advertising strategy. I visit Nick's site often, and so too should you, and there you will find all manner of wonderful things -- but not, unless I have missed it, much about Loxosceles reclusa. What's more, Nick tends to focus on Britain; the recluse (not to mention the black widow and the hobo spider) lives in a place that once was British but hasn't been for more than two centuries.¹ But if Google's magic formulae decree that Nick's site is swamped daily by arachnophobic midwestern Americans then it must be so, and the spider-trap manufacturer is getting good value for money. (Before clicking through to the ad site, you should know that it contains some grisly pictures of what a recluse bite can do. Scroll right down to the bottom!)

UPDATE: I have just noticed that the first of these two ads is not for a spider trap but for a 'herbal paste' to treat necrotic wounds from recluse bites. This is pernicious nonsense. There's not much one can do about a necrotic bite, beyond trying to keep it clean and free from superinfection. (Attempts have been made to speed up healing using dapsone and hyperbaric oxygen therapy, but the reviews are lukewarm.) This product will almost certainly do nothing to heal a necrotic wound (though it could possibly have a mild antiseptic effect, which might help discourage superinfection). If it seems to make 'necrotic recluse bites' heal faster, those were probably never recluse bites to begin with. Such bites are massively misdiagnosed in the US, by laymen and physicians alike, as you will learn from the links on Rick Vetter's recluse page. (One of the testimonials in the Google ad, for example, is from a woman who lives where the recluse does not.) The ad claims the product works by drawing out the venom 'that kills the cells and causes such gruesome and painful sores'. If that statement indicates the company's knowledge of recluse toxology, they have no business selling remedies to anybody. The 'gruesome, painful sores' are caused by the victim's own immune system, thrown out of whack by a component in the spider's venom. By the time an initial wound is visible, the venom has done its work (if it has done so at all; recluse bites only sometimes cause a necrotic wound) and it is too late for the paste to do what its sellers claim. I doubt Nick has any control over the ads that appear in the Google column, but this 'herbal remedy' is at best useless -- and potentially harmful, if it keeps you from seeking treatment for conditions, like Lyme disease, whose symptoms are frequently misdiagnosed as recluse bites. The spider traps, at least, could serve as a conversation piece on your coffee table.

¹ Arachnological pedantry, for those who care about this sort of thing. The brown recluse, L. reclusa, is endemic in the lower part of the American midwest, as you will see on this map from Rick Vetter's page. (And I mean really endemic; they infest the place. That medically significant bites are so rare in relation to the spiders' high numbers suggests that they are not terribly interested in biting people. If you live where recluses live, you should be aware of their potential danger, but the rational response falls far short of screaming in panic. If you want lots of info about the recluse in a very user-friendly form, visit this site run by the University of Kansas's recluse guru Jamel Sandidge.) There are other Loxosceles species in the USA, but only the brown recluse is synanthrope (i.e., likes living in people's houses). Some of the others presumably have bites potentially dangerous to humans, but these live in remote corners of the western desert. (In Los Angeles, however, there is a small colony of L. laeta, a non-native species introduced from South America, where it is considered dangerous in much the same way the brown recluse is in the US midwest.) There is one species in Europe, L. rufescens, but it is limited to the Mediterranean region and is in any case probably too small to bite you.

'Black widow' is a loose term for various spiders of the genus Latrodectus. Many of the American variants display the famous 'red hourglass' on their underside. They live in many places in the USA, and have cousins with somewhat different markings called (for example) the button spider in South Africa or the redback in Australia. There is also a European species, L. tredecimgutattus, a handsome beast with, as its name implies, a number of bright red spots on its shiny black body. Like L. rufescens, it lives in the warm climes of southern Europe. The French call it the malmignatte; to the Russians (it is found on the shores of the Black Sea) it is the karakurt. But to my knowledge it does not live in Britain or anywhere near it.

The hobo spider, Tegenaria agrestis, is a funnel-web spider. That is to say, it is an Agelenid, closely related to the enormous and scary-looking (but harmless) T. duellica and T. atrica you have probably seen in your cellar. (It is not related to Australia's highly venomous Sydney funnel-web spider, Atrax robustus.) These spiders live in the American northwest, where they are synanthropes. Curiously, they are also found (unlike Loxosceles and Latrodectus) throughout the temperate zones of Europe (including in Britain, where they were first recorded in 1949). Indeed Europe is where they come from; they are immigrants to America, brought over inadvertently in a shipment of lumber. What is curious is that they are not considered a medical threat in Europe. So far as I know there have been no recorded bites of medical importance over here, and it is only the most recent (and now online) edition of the key to central European spiders that I use that has begun to note parenthetically that T. agrestis has caused problems across the sea. The difference, perhaps, lies in the fact that in Europe these spiders are rarely synanthrope, being found instead among stones in fields and meadows. There is a useful site about the hobo spider here, founded by Darwin Vest, the gifted amateur arachnologist who vanished mysteriously in 1999. Vest was instrumental in convincing a sceptical US medical establishment that a spider was responsible for a number of puzzling cases of necrotic wounds in the northwest (and that the spider in question was not the recluse).

In any event, those of you in Britain have little to fear from spiders. There are a few (a very few) species there that could give you a painful nip, but none that will do real damage; and you are very unlikely to have a dramatic encounter with them. So save your money; you may sleep easy even if you do not own a spider trap.

Friday arachnid blogging; or, nomen non est omen

This intermittent series of Friday arachnids has not gone over to an all-crab-spider format, I promise you. It's sheer coincidence that this is the third crab spider in a row. Ah well, she is at least a Philodromid rather than a Thomisid--a spider from the genus Tibellus. At first glance, though, you might not think her a crab spider at all:

She hasn't the typical crab-spider habitus at all (though the shape of her prosoma is very crab-spiderish). In fact what she really resembles, at first glance, is a kind of spider known as Tetragnatha. Now, there's a bit of controversy over where to place the Tetragnathids, systematically speaking; but all the possible places for them can be described as 'not close to the crab spiders'. Yet Tibellus looks like a Tetragnathid, and even acts like one: if you see her in the wild, it will likely be in her characteristic pose, stretched out along a blade of grass.

(A closer glance, of course, and the resemblance begins to dissipate. Most obviously, Tibellus has the tiny 'jaws' (chelicerae) typical of crab spiders. Tetragnatha, by contrast, has enormous hinged jaws that give the family its name ('four jaws'). And Tetragnathids, unlike crab spiders, build webs. (One genus within the family, however--Pachygnatha; stockier beasts than Tetragnatha--gives up web-building when it becomes an adult, going instead on the hunt, like Tibellus).

I found this Tibellus in the wild, but not in her usual stomping-grounds. She was stowed away on a ferry from Formentera to Eivissa. If you look very carefully in the photo, you might see a pair of black dots at the back end of her abdomen. This marks her as Tibellus oblongus. Had the black dots extended in two parallel rows all along her abdomen, she'd have been Tibellus maritimus--and wouldn't that have been so much more appropriate?

Friday arachnid blogging, with the sexy bits left out

Last Friday's spider, Xysticus, was of plain if pleasing appearance. This week, let's have a look at her more glamourous cousin, Thomisus onustus, whose genus gives the family Thomisidae its name:

Our spider is brilliant yellow, but the species comes in a broad run of bright colours. Some are white with yellow or pink stripes. Some have a prosoma (head/thorax) and legs of deep, nearly blackish purple, and a pink abdomen dappled with white flecks.

It's what I can't show you that makes me sorry. What makes me even sorrier is that I didn't get to see it myself. I found this spider on a flower (where else?) outside Sant Ferran on Formentera. It was a very windy day; stormy, really. On the next flower over was another T. onustus: the darker, much smaller male.

It would be a treat to watch him court the female. Many of the Thomisid crab spiders, you should know, have a taste for S&M. Before mating, the male binds the female to their flower-bed with cords of silk. Would T. onustus do the same?

This bondage is all play-acting, by the way; when the male is finished, the female easily shrugs off the cords. But the act of binding somehow puts her into a docile, receptive state, and she is unlikely to make a meal of her mate (as some spiders do, but fewer than you might think).

Alas, I would never find out whether T. onustus shares the kinkiness of some of its cousins. Just as the male was trying to climb over onto the female's flower, whoosh, a strong gust of wind sent him sailing away, far in the opposite direction. Frustrating for me, and doubtless more so for him.

Friday arachnid blogging: back once more

... and, my word, it has been a while, hasn't it?

No digressions today on the metaphysics of taxonomy or anything like that. Instead, I'd just like to show you a pretty spider. And here she is, Xysticus sp. (X. cristatus in all likelihood, to judge by the dark-tipped triangle stretching back from behind her eyes; but she could possibly be X. audax instead. Both species are very commonly found in middle Europe.)

Pretty, did I say? Well; jolie-laide more like, perhaps. She is nothing to compare with the real beauties of the Thomisid crab spider family, the living jewels of the genera Thomisus and Misumenops and so on. And yet, as the great arachnologist WS Bristowe wrote of the less gorgeous Thomisids, 'there is something very attractive about even the plainest ones, similar in some respects to the plainness of a toad.'

There's a reason why Xysticus doesn't come in the gorgeous flower-like colours of some of her cousins, and that's because, unlike them, she doesn't hang around on flowers. Her revier is the world of leaves and twigs and stalks and stems. But she catches her prey in the same way. Stock-still she sits, for hours if need be, till some unfortunate insect passes within reach of those Popeye-like forearms. And then whammo, and bon appetit.

Formentera's other lizards

A couple of months ago I wrote about the ubiquitous lizards of Formentera. I mentioned that Formentera has another lizard, a shy and nocturnal gecko. In a recent comment to that post, a Mr or Ms Lagarto of the Lacerta web project (English version here) corrects me; Formentera has two species of gecko (both immigrants, by the way), Tarentola mauretanica and Hemidactylus turcicus.

Here's a piccie of the only gecko I ever managed to catch on Formentera (and only the second I'd ever seen there):

I've no idea whether this is T. mauretanica or H. turcicus. Our correspondent notes that the latter is even shyer than the former; so perhaps it is the Tarentola. Shy though the gecko in the picture was, it made a number of tactical errors that led inexorably to its being in my hand; had it been the other sort, perhaps I'd never even have seen it.

The other gecko I saw on a wall late at night on an earlier visit to the island. It was feasting on insects attracted by a light. Rather larger than the gecko I caught (who might, though, be a juvenile), it was a thing of ethereal beauty: ghostly pale, dappled with pastel peach, pink and purple. I moved with the care of a hunter to get my camera, but that was enough to spook her. I have seen very few things as beautiful.

Do check out the Lacerta site, by the way; more lizards than you can shake a stick at, and some of them very good-looking indeed.

More strange sea creatures from Monterey Bay

Francis Crick has died, I learned today. His achievements will ensure that his memory lives on. But is it not fitting that, as a man who did so much to unlock the secrets of life for us takes his leave, a new and wonderful living thing enters our world?

Well; the bizarre marine worms of the genus Osedax are not really new, though as AP reports they are new to our knowledge. Like the four-armed jellyfish Stellamedusa ventana, they have been found in the waters of Monterey Bay off California.

This is Osedax frankpressi. Like her cousins O. rubiplumus she lives on the skeletons of dead whales at the ocean floor. She lacks a stomach, but that's all right because she harbours bacteria within her that digest fats from the whale bones. She's a few cm long but her husbands--of whom she may have hundreds--are much smaller and live inside her, reduced to little more than sperm factories for her eggs.

DNA analysis suggests that Osedax number among the Siboglinidae, related to those worms--whose pictures we've all seen--that live in the unbelievably hot and sulphurous waters round hydrothermal vents. Like Osedax, the vent worms have harnassed bacteria for a living, albeit in a very different way.

A big tip o' the T6I tam-o-shanter to GW Rouse, SK Goffredi and RC Vrijenhoek for bringing Osedax to the world's attention. You'll find the abstract of their paper in Science here, though I'm afraid you'll need to register to see even that, and pay lots of money to read the paper itself. Or, you can stroll on down to the library with the citation in hand:

Osedax: Bone-Eating Marine Worms with Dwarf Males
G. W. Rouse et al.
Science, Vol 305, Issue 5684, 668-671 , 30 July 2004

Happy reading!

Would Rosaceae by any other name smell as sweet?

The Panda's Thumb spends most of its time swatting down creationism, especially in its shiny new guise of 'Intelligent Design Theory'. But the truly interesting stuff is real biology, and the Thumb takes time to discuss this as well.

The other day I talked in a very simple way about some of the implication of naming a species. Today, TPT's John Wilkins goes a lot farther, recounting the history of Linnaean classification and talking about a proposed replacement, Phylocode, that would cleave far more closely to phylogenetic history. It's all fascinating stuff, and highly illuminating in pondering whether our classifications of organisms relect some kind of 'reality', or are simply so many names.

More blogs about spiders and webs

If lizards as a substitute for spiders just don't do it for you, or if you simply can't get enough of the little beasts, check out Dinesh Rao's Spiderblog. It's like having an aggregator of all things spidery.

Saturday lizard blogging; or, Woah, oh, what I want to know is, are you (the same) kind?

Those of you who stopped by yesterday for your usual Friday spider fix will have been disappointed, I fear. The curse of earning my bread kept me from my customary spider blogging, for which I am (if possible) even sorrier than you are. But then lizards are in so many ways so very nearly indistinguishable from spiders (eukaryotic; bilaterally symmetrical; really cool) that they may readily serve in the same role. And Saturday is Friday in the base-6 calendar system, or something. So this week it is Saturday Lizard Blogging you shall have.

As I hinted in my first post after returning from Formentera, you can't spend much time on the island before you notice that it is home to a lot of lizards. And I mean a lot. These things are all over the place. By 'these things', I mean Podarcis pityusenis, and here is one of them:

The Formentera lizard has become practically a trademark of the island, and rightly so. Not only ubiquitous, they are attractive, and cheeky as sparrows. Those who live near the open-air beach restaurants will dart under your table to gather crumbs, and with a few minutes' patience you can coax even those living in the parts of the island rarely visited by humans to eat out of your hand (a small piece of apple or banana will do nicely).

But I don't merely want to show you a picture of a good-looking lizard. The Formentera lizard also gives us a good excuse for thinking about something most of us never give much thought to. That is, what do we mean when we say 'species'?

Most of us, I think, would say that 'species' is the scientific term for any particular kind of organism. (And indeed, 'species' is merely the Latin word for 'kind'. ) Thus Felis domesticus is our friend the cat, and we ourselves are Homo sapiens.

(You'll have noticed, of course, that to refer to a species we actually need to use two names, one for the species and one for the genus that contains it. In the Linnaean tradition of 'binomial nomenclature', the first, capitalised name identifies the genus; the second, the species. The rules dictate that each generic name must be unique (within the zoological world; botany has its own set of rules); specific names may be used over and over, though of course only one time in each genus. Thus you can't name the species without naming the genus at the same time.)

Now that all seems pretty clear-cut, doesn't it? So why does Podarcis pityusensis raise questions about what seems nothing more than a convention for assigning names?

Well, within this species we find two kinds of animals that look rather different to each other. As the scientific name implies, the lizard is native to the Pityusan Islands, the western subset of the Balearic Islands off the eastern coast of Spain that comprises Eivissa (as it's properly called, though most of us know it by its Castilian name of Ibiza) and Formentera. Though the lizard has been artifically introduced to Mallorca (and doubtless smuggled home by any number of tourists), it occurs naturally only in the Pityusans. And its common name is the Ibiza Wall Lizard.

The only problem is that you won't find any lizards on Eivissa that look like the ones in this post. You might well see many lizards if you go there, but they are a drab yellowish-brown. The lizards of Formentera, by contrast, show gorgeous hues of emerald, turquoise and jade:

I try not to spend any more time on Eivissa than is needed to get from the airport to the Formentera ferry so I haven't a picture of any lizards from the larger island. But if you go here you'll see the two islands' lizards compared; the one on the bottom is from Eivissa.

Obviously the two sorts of lizard are quite similar, but just as obviously there is a dramatic difference in colouration. Are they different species?

They are not. The brightly coloured version is known technically as Podarcis pityusensis formenterae. That second name after the generic name identifies P. p. formenterae as a subspecies of P. pityusensis.

'A subspecies?', you say. Isn't this just so much category-mongering? The two animals look different and live in different places. Why can't we call them two different species?

The answer is that 'species' has two subtly different meanings. In one sense it is a mere unit of taxonomy (the discipline of classifying organisms into multilevel categories and assigning names to reflect that categorisation). In that sense, there's nothing to prevent us from giving the Formentera lizard its own species name to distinguish it from its drab Eivissan counterpart. For that matter, there's nothing to prevent us from setting up a system of Linnaean categories to classify houses or items of clothing. 'Species' in this sense is a name and nothing more.

But in another sense, 'species' is a 'real' category. A specific name identifies an organism as belonging to a unique group that stands apart from all other groups on the basis of some objective standard (and we will talk in a moment about what that standard might be) other than mere naming.

Classically, a plant or animal would be assigned to a species according to how closely it conformed to 'type'. Species were defined on the basis of a type specimen, which became the yardstick for species membership. (And if some organism didn't seem to conform to any known and defined type, it would probably become the type specimen for a newly-defined species.) If 'species' in the first sense was pure nominalism, 'species' in this second sense was Platonism: the type specimen was the (admittedly rather arbitrarily chosen) Essence, all other species members emanations therefrom.

Then along came Ernst Mayr and decided that this simply wouldn't do. (In fact he wasn't the only one or even the first to complain, but his Systematics and the Origin of Species from the Viewpoint of a Zoologist - a work intended primarily for scientists but eminently readable for laymen - is the classic exposition of what is now known as the biological species concept.)

Early in the course of his long and extremely distinguished career, Mayr went to the South Seas to study birds. Now birds perhaps more than other groups of animals have been a battlefield between 'lumpers' and 'splitters'. Mayr found that his birds had in many cases been split among a bewildering number of species; numbers that he thought unjustified when he began to think about what 'species' means. He found that there could be a very broad morphological variation among birds that bred as a community. (That is, birds would mate and produce offpring with different-looking birds.) Though morphological differences would tend to follow geography (e.g., average size, colouration or shape of tail would vary predictably as one went from island to island in an archipelago), breeding populations could nonetheless merge imperceptibly into one another as one made one's way across the geographic range.

Mayr decided that, if anything showed membership in a common species, it was the ability to interbreed successfully. If two animals did that, they were conspecifics, no matter how different they might appear to each other. And if that was the case, then the old Platonic 'typological' species concept was starting to look very shaky.

And indeed, the typological concept has given way to the biological species concept. (There are other species concepts; and, as we shall see, the biological concept is not without problems of its own. But the typological concept is pretty much history now.) Taxonomists still preserve type specimens, but nobody sees them as Platonic ideals anymore.

Under the biological concept, a species is a group of reproductively isolated organisms. This does not mean geographic isolation; it does not mean differing appearance. Two populations of organisms may be separated from each other by geography or appearance. The Formenteran and Eivissan populations of P. pityusensis are separated by both. But if you put members of both population together, they can and will mate, and their offspring are fertile. Hence they are members of the same species.

(Conversely, there are animals that are morphologically indistinguishable that live side by side yet do not interbreed. In fact, this is a pretty common phenomenon. Under the old typological species concept, they'd have been lumped in together. Today, they are recognised as separate species. Mayr translated a word from his native German to give us English-speakers the term 'sibling species' to describe such related yet biologically distinct groups.)

In thinking about all this it is important to remember that species classification is a snapshot. When we say that the long-tailed birds of island A and the short-tailed birds of island B (or the lizards of Formentera and Eivissa) are members of the same species, we contemplate them frozen in a single moment of evolutionary time (and in evolutionary time, a moment may be very long indeed). Given enough time, it is of course entirely possible (though by no means necessary) that the two groups will come to differ enough, whether in body chemistry, behaviour or what have you, that they would no longer be able to interbreed even if they were reunited. Thus every subspecies within a species is, at least potentially, a new species in the making. This thought is at the heart of the concept of allopatric speciation, the process by which most biologists think that independent species usually (though not always) arise. But speciation is not a snapshot, it is a movie. At any given moment in time, a species is a group of organisms united with each other at least potentially, and divided from all other organisms, by reproduction.

Now, the biological species concept makes eminent sense and represents a major conceptual achievement in systematics. But there's probably a vague uneasiness gnawing away at you as you think of it. That uneasiness takes form when you ask yourself, 'What about organisms that don't reproduce sexually?' And there are a lot of these (billions of them are swarming in your guts as you read these words). Even among multicellular animals there are many asexuals. Most of the time these are relatively isolated groups tucked in among a larger group of sexually reproducing animals; the odd lizard, the occasional harvestman. Yet within the class Rotatoria there is an entire order (that's a pretty high-level taxon; by comparison, within the class of insects beetles make up one order), the Bdelloidea, that is entirely asexual - not a male in the lot. Under the biological concept, what does 'species' mean for such animals? Can we call each individual bdelloid rotifer a species? Can we call all clones tracing their ancestry to that individual a species? The answer is, yes, I suppose we could, except that in that case the term 'species' would cease to have any use. You will recall from way up above, though, that 'species' has two senses. It is a biological concept; but it is also a purely taxonomic unit. Faced with asexuals we may certainly assign them a standard Linnaean name as a convenience, an indicator that they are more like each other than they are like anything else. And, in such cases, I would imagine that typology continues to hold sway. Awkward, I grant you, but at least here we find Platonism and nominalism united in unexpected harmony.

But P. pityusensis does not present us with the vexing issue of asexuality. And the fact that it doesn't explains why we cannot accord the lizards of Formentera, beautiful though they may be, the dignity of their own species. They are beautiful, though, so here's one last look:

A young H. sapiens holds a young P. pityusenis formenterae; neither was harmed in the making of this post.

A stroll along the Tangled Bank

Another of PZ Myers's splendid ideas has come to fruition. He has innaugurated The Tangled Bank. The Bank is... well, why don't I just quote Prof. Myers:

In cooperation with several other of us geeky science types, I am pleased to announce our own version of the "Carnival of the Vanities". A Carnival is a weekly showcase of good weblog writing, selected by the authors themselves (that's the vanity part). Each week, one of our crew will highlight a collection of interesting weblog articles in one convenient place, making it easy for everyone to find the good stuff.

Two things will distinguish us from the original "Carnival of the Vanities": 1) we are specifically restricting ourselves to articles in the field of science and medicine, very broadly defined, and 2) we've got a different name.

Tangled Bank is not so much a blog as a sort of floating metablog, a collection of commented links to posts contributors have made on their own blogs. The idea is that the reader will find, conveniently collected in one easy-to-use place, a variety of articles on all manner of things, united only by that very broad definition (and its breadth is important!) of 'science- or medicine-related'.

There is, nonetheless, a Tangled Bank mother-ship website. There you will learn more about the project, including how to contribute; you'll also find an index of who's hosting the Bank when, with links to their websites.

Full disclosure: Prof. Myers was kind enough to include one of my spider posts in the first round. I say this not to blow my own horn (though I am dead chuffed) but to underscore the ethos of the project. You needn't be a professional scientist to participate. Certainly there are pros taking part; but even then, what they post is not the passive-voice-only stuff you'd find in a peer-reviewed journal. As it says on the 'home' website:

Anyone can submit an entry. Even if you don't routinely write about medicine or biology, if you just happen to have written about your gall bladder surgery that week or the pileated woodpecker that has taken to waking you every morning, if you think you've said something interesting and insightful, send it in.

Friday arachnid blogging in absentia; or, Early Monday morning is losing its appeal

As you read this I will be finishing packing up. We are taking the brood off for two weeks' holiday in the Illes Baleares. Specifically, we are headed to Formentera, a small island just south of Ibiza but virtually devoid of the discos etc. that make Ibiza so nice a place to get off a plane and onto a ferry.

So there'll be no posting, and therefore no Friday arachnids, till after the middle of April. Now I know there are millions of you who turn faithfully to this site every Friday for your spider fix. To keep you from jonesing too badly, I've stuck not one but two spiders below the fold; and a couple of pictures of each. Both are spiders I collected on Formentera in 2001; both are a bit unusual.

We'll start with Loxosceles rufescens. This is the Mediterranean cousin to the infamous American brown recluse, L. reclusa. Here he is while he still walked among the living:

You'll note that he has but six eyes, arranged in three pairs or dyads, like past Friday Arachnid S. thoracica. In fact, these two spiders are from closely related families. You'll also note from the swollen tips of his pedipalps that he is a sexually mature male. The simple structure of these 'manual genitals' marks L. rufescens as a member of the Haplogynae, a relatively small and 'primitive' group within the araneomorph spiders (i.e., the main branch; more on this below).

Here's a close-up of his prosoma. You can see the 'violin-shaped' marking that gives his American cousin the nickname 'fiddleback spider'.

If you look closely, you can also see the fine-pointed ends of his emboli, the turkey baster-like thingies at the ends of his palps. These he fills with sperm, later to be squirted into his mate.

Judging by this specimen, fully grown at 5 mm in body length, I'd say that L. rufescens is a bit smaller than L. reclusa (of which there is a picture here). Presumably they have similar venom. It's nasty stuff altogether. The bite itself, so I've read, is not painful, indeed most victims don't feel it. And most victims never know they've been bitten because the venom has no effect. But in a significant minority an ugly, slow-healing necrotic wound develops at the site of the bite (a much smaller minority will have a dangerous and potentially lethal systemic reaction.) An interesting and little-known fact about L. reclusa, recently reported by Jamel Sandidge in Nature, is that this spider, unlike almost all others, is a scavenger: it prefers dead prey to living. I could not begin to say whether L. rufescens has the same habits, but I will keep a cold eye on any dead flies I may note on the windowsill.

Now we'll turn to another spider that is a bit of an outlier. This is Nemesia sp. Again, we'll start with a picture of her still alive, in a little glass phial:

Nemesia is a mygalomorph spider. That is, she is part of a discrete group considered more 'primitive' (closer to the ancestral state) than the araneomorphs, or 'true' spiders. Mygalomorphs as a general rule are bigger and longer-lived than araneomorphs. They include those huge hairy dinner-plate sized things we all call 'tarantulas', though this is a misnomer - the real tarantula is an araneomorph, a Mediterranean wolf spider that, though quite large, isn't nearly as big as the mygalomorph 'tarantulas'. But the mygalomorphs also include quite tiny creatures, including a minuscule (and endangered) American sort that lives in the moss growing on the sides of trees. As for our Nemesia, she is 17 mm long, ignoring her legs.

Mygalomorphs differ from 'true' spiders in a number of ways, some of which we'll look at. The most obvious difference is the orientation of the chelicerae, the 'jaws' bearing fangs at their ends. Mygalomorphs are orthognath; that is, their chelicerae move in parallel, striking downwards. Araneomorphs are labidognath - the chelicerae face each other and the fangs close in a pinching movement. If you want to imitate an araneomorph, you need to put your thumb and index finger in front of your mouth and snap them open and shut. To imitate a mygalomorph, put your index and middle fingers in front of your mouth and move them up and down.

Nemesia is a 'trap-door' spider. She lives in a burrow with a hatch on top, and pops out to nab passing prey. That's about as sophisticated as trapping technology gets among the mygalomorphs. Most wander about and eat whatever they come across and can take down. Some, like Nemesia, build trap-door burrows. A few - the purse-web spiders - extend the burrow outwards with a silken tube, and bite their prey through it. The Australian funnel-web spider, Atrax robustus, builds primitive webs a bit like those of the araneomorph Agelenidae. (Atrax, BTW, is a very dangerous spider, with venom that can be deadly for humans and other primates but not, oddly, for other mammals.) But no mygalomorphs build the marvelous webs most people associate with spiders.

Let's take a closer look at our Nemesia, who is now quite docile, because dead:

Here you can clearly see how her chelicerae jut straight forward. Thery're very big, compared to those of most araneomorphs, but her venom glands are small, being contained within the chelicerae (in araneomorphs, they extend back into and occupy a good bit of the body). Note also the eyes (she has eight of them), crowded together on a tiny hump. Finally, note her spinnerets, two of which extend visibly beyond her tail end.

If we flip her over, here's what we see:

Spiders don't have lungs as we know them, i.e., inflatable bags that are pumped full of air. They have 'book lungs', a sort of internal cavern with a large surface area across which oxygen diffuses. The air gets in through a slit on the belly. Virtualy all araneomorphs have one pair of book lungs. Their ancestors bore a second pair but this has become reduced to a so-called trachaeal slit (most spiders have one, a few have two) that leads to small tubes bringing an extra bit of air to the spider's interior. The mygalomorphs still have both ancestral pairs of book lungs. In the picture above, you can very clearly see the posterior pair (dark slits just in front of the midpoint of the belly). The anterior pair are a bit harder to see, as their slits run right along the epigastric furrow, a sort of trench running from side to side along the front part of the belly, beneath which the genitalia lie.

And, if you're looking at the epigastric furrow, there's something you won't see: an epigynum. This is a sclerotised plate covering the female genital openings. It's only present in the entelygynae, i.e., the 'higher' araneomorph spiders. The absense of an epigynum makes it very hard to idenitify Nemesia specifically. To do so with any precision, you need to catch a sexually mature male, and those are hard to come by. With any luck, I'll find one in the next two weeks.