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.

Friday arachnid blogging: Say no to drugs!

If you've spent any time at all learning about spiders, it's a safe bet you'll have heard of Peter Witt's famous 'drug web' experiments¹. Witt administered a variety of drugs to orb-weaver spiders, who normally make those beautifully symmetrical 'classical' webs we have all admired. Then he and his assistants sat back and observed how the drugs influenced the structure of the webs. (By the way, Rainer Foelix, the Swiss arachnologist whose Biology of Spiders is the standard modern reference, got his start working in Witt's lab.)

For obvious reasons, it's more interesting to see this sort of thing directly than to read about it. Here's something I came across that dramatically illustrates how drugs can interfere with natural functions:

1) See, for example, 'Drugs alter web-building of spiders: A review and evaluation', Behav. Sci. 16 (1971)

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.

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.

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'.

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.

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.

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.

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.

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.

Friday arachnid blogging, and what's in a name

After last week's grand-guignol, here's a more pastoral scene altogether:

The orangey spider tucked in among the purple petals is one of the 'running spiders' or, more properly, philodromid crab spiders. She is very likely Philodromus rufus though, as she is a juvenile, it is extremely difficult to identify her precisely.

The name 'running spider' might seem odd. After all, most spiders (at least those that do not spend their entire lives on a web) run. But in this case the popular name derives from the Linnaean name Philodromus, 'one who loves to run', and they are quick little things indeed. What is really interesting here is the term 'philodromid crab spider'. They are so called to distinguish them from the thomisid crab spiders. Remember that terminal -d, by the way, because it's going to be important.

If you've gone to look at the thomisids on Ed Nieuwenhuys's excellent website and compared them to my young philodromid, you'll probably have noted that they look very much alike, save for one detail. The thomisids have stubby little hind legs (pairs 3 and 4) while their two forward pairs of legs, especially the first pair, reach heroically Popeye-like proportions. The forward legs of the philodromids are very similar, but their hind legs aren't nearly as stubby; in fact they look more or less 'normal'.

Now, before we contemplate drawing any conclusions about the degree of relation between thomisids and philodromids, we can explain the difference in leg pattern by the respective lifestyles of the two sorts of spider. Philodromids chase down their prey. Thomisids sit stock-still on a plant, often in the middle of a flower, and wait until an insect walks into the grasp of their prodigious forearms; then wham and it's lunchtime.

People used to say 'Well, we have crab spiders; clearly this one sort are different to the other sort, so we'll give them different names, but they're essentially part of the same group'. And so we had all of these spiders in the family Thomisidae, with the short-rear-legged lot called Thomisinae and the longer-rear-legged lot called Philodrominae. The -idae ending denotes a family (one level up from genus in the classical hierarchy), while -inae denotes a subfamily.

What you need to know about taxonomists (people who classify organisms) is that they fall into one two big groups, the lumpers and the splitters. As the names suggest, lumpers are inclined to shove disparate organisms into a single group if they have any shared characteristics; whilst splitters are, shall we say, much given to celebrating diversity.

As far as the crab spiders go, the splitters have tentatively won the day. Today one no longer speaks of Philodromines but of Philodromids. The d makes all the difference; the spider in the picture above is not part of a sub-goup of Thomisidae but rather member of an independent family in its own right, the Philodromidae.

This might strike you as so much hair-splitting, but it isn't. Almost all taxonomists these days have adopted a cladistic worldview. Cladistic systematics is notorious for rigidly dogmatic insistence on an essentially Martian terminology, but brush aside the bizarre words and it's pretty intuitive and (I think) sound: if you want to divide up the world's organisms, the terms you use should reflect the actual evolutionary history of those organisms.

To use a concrete example: as we've all heard, 'birds are really dinosaurs'. This might strike you as odd, given that (i) dinosaurs, as every shoolchild knows, became extinct a squillion years ago and (ii) that thing on your plate is a chicken, for chrissake, not a dinosaur. But to a cladist (and we are all cladists now), the point is that no taxonomic group is 'real' unless it contains all the organisms descended from a single common ancestor, and no organisms not descended from that ancestor. Birds as we know them today arose within one particular group of reptiles; that group was the dinosaurs. So a Tyrannosaurus and a chicken are more closely related to each other than either is to a lizard or snake. They are each members of a single clade, descended from a common ancestor not shared with lizards or snakes. Under the conventions of cladism, therefore, the term 'dinosaur' is only legitimate if it includes the birds. If it does not, then it fails to contain all the descendants of a single common ancestor. If you wish to refer only to the sort of dinosaur that looks like Godzilla and is extinct, cladists would insist that you say 'non-avian dinosaur', which is ideologically pure but, if I may speak frankly, a bit clunky for use in any but a technical context. Birds, lizards, dinosaurs and snakes, of course, are all descended from a more remote common ancestor, so they all legitimately belong to a larger clade than that of the dinosaurs (and birds). Clades fit within clades, a bit like those Russian matrioshka dolls we've all seen. (BTW, cladists wince at the term 'reptile' itself, for the reasons described above. They'd let you say 'reptile' so long as you were willing to include yourself in that group. Otherwise, if you mean what we all mean when we say 'reptile', you had better say 'non-mammalian, non-avian amniote' when you are talking with a cladist.)

When the Philodromines became Philodromids, then, a lot more was going on than the mere swapping out of a couple of letters. The assertion was being made that a biggish group of animals was not a single group at all; that they did not all share a single common ancestor. (Of course the running spiders and thomisid crab spiders do share a common ancestor in any case; but that ancestor was being pushed back at least one level.)

This might all seem very rarified and academic to you, but think of an example a bit closer to home. Are you a chimpanzee? You might be tempted to answer indignantly that you are not. And, in a tightly focused context, you may legitimately distinguish yourself from chimpanzees - today's chimps and bonobos share a common ancestor that we don't have. Yet if you broaden your focus just a little a bit and wish to distinguish yourself from a gorilla, you are going to have to take our chimpanzee cousins along for the ride. For we and they descend from a shared common ancestor that arose after our lineage split from the lineage leading to gorillas. It's understandable, perhaps, that we instinctively divide the primates into two great groups - ourselves and all the others. But there is no systematically legitimate way to hive humans off from other primates unless we take the chimpanzees with us. They are no more closely related to gorillas than we are. Indeed, since the ancestors of (chimps + bonobos) split off from a common lineage after the ancestors of ((chimps + bonobos) + humans) did, from a cladistic perspective it's not so much that humans are a sort of chimpanzee as that chimpanzees are a sort of human.

Friday arachnid blogging (finally, something gets eaten!)

Sometime visitor to my comments box Albert Law complained that I never show spiders doing anything. (Fair point, though then again for most spiders, life consists mostly of hanging around motionless.) Albert asked whether I might not show a spider eating something. I live to serve:

The spider is Araneus diadematus, the very common garden spider. She's known in German as the Kreuzspinne, and no prizes for guessing why. (I do have a plate from a very old English book on spiders that calls her, under the earlier form of her Linnaean name Aranea diadema, the 'white cross spider'; but I do not believe she is generally called this in English today.) Her meal is the common wasp, Vespula vulgaris.

Normally I shouldn't think that A. diadematus would eat many wasps. They're big and strong enough to break out of her web quite quickly (though it's true that orb-web spiders are very fast in getting to their prey once the latter hits the net); and they're armed and dangerous. But this was in early autumn, when the vespan hordes that torment us all summer long begin to die away and those still alive are slow and stupid (and hence prone to losing their lives, as the unfortunate subject of the photo has done).

The spider's method of processing the wasp was interesting in itself. Many of the more 'advanced' orb-weavers carry out a quick assessment of their prey to decide how to deal with it. Smallish captives may be dispatched directly with a bite. Bigger and more dangerous captives are first wrapped carefully in silk from a discreet distance. The spider may then bite the immobilised prey in perfect safety. You may have seen the big yellow-and-black orb-weaver Argiope doing this with grasshoppers, perhaps in life, perhaps in the amazing film Microcosmos. (BTW, it might strike you as odd to think of a grasshopper as 'dangerous'. He is certainly not dangerous to you, but he can shear off a spider's legs quick as a wink. There are even carnivorous grasshoppers, and extremely aggressive little things they are too. Argiope is a big spider, but she's wise to take precautions.) But this A. diadematus took a sort of via media. She did wrap the wasp, flinging sheets of wrapping-silk over its body. But she didn't wrap it at all thoroughly; you can easily see the body through the strands of silk, whereas wrapped insects are usually completely, heavily swathed.

Friday arachnid blogging

Ask most people how a spider catches her prey, and they will say 'in her web, of course'. True enough for a great many spiders, but then again there are also a great many that go on the hunt and wrestle down whatever they can take. But some spiders have unusual ways of getting their food, and this is one of them:

She is Scytodes thoracica, the spitting spider. And spit she does. Note her high-domed prosoma. It houses very large venom glands, only part of which makes venom. The rest makes glue. As she approaches her prey, she shoots zigzag bands of glue over it, pinning it to the substrate (e.g., your ceiling). Then she comes in cautiously for the bite.

Hard to see in this picture (I must apologise; I really hadn't quite sussed the camera's macro settings when I snapped it), but she has six eyes instead of the usual eight. These are arranged in three dyads, or pairs, at the front of her prosoma. You can see a dot of light reflected on the left side dyad, and the central dyad is in what looks like a little black nose right up at her front. In spiders that have the full complement of eight eyes, the anterior median eyes (the middle two in the front) are very different to the others. When spiders have six eyes, it is the anterior median pair that is missing. The eyes they do have, unlike the anterior medians, are built rather like our own. That is, the light-sensitive part of the retina faces backwards away from the light. Not very efficient, you might think; but we seem to get by well enough, and so does S. thoracica. Even harder to see, she's drinking a drop of water we gave her, holding it to her mouth with her dainty little pedipalps.

I should mention that this particular S. thoracica was collected by my daughter, then five. She found it in our dresser drawer, remarking 'It's the spitting spider!' (I suppose she must have seen one in one of my spider books, most of which are visually rather boring keys or monographs but some of which are full of beautiful photos.) I didn't particularly care for a spider in my dresser drawer, and thought she'd have trouble finding anything worth eating there anyway. So we released her in the kitchen in the hope she'd hunt down any little bugs that might come in the window. We saw her from time to time over the next few weeks, and I hope she enjoyed her stay.

Keep your eyes out and you might well see one yourself, for all that your retina is put in backwards. They're not rare, and I believe they live just about everywhere. Certainly I've seen them in North America as well as in Europe.

Friday arachnid blogging

Now here is a spider that is common enough, at least in Europe, but often overlooked. She is called Nigma walckenaeri, and she looks like this:

You might overlook her, because she tends to be the same colour as the place she lives. And that is usually on a leaf. She chooses a concave leaf and spins her net across its top. When an insect tries to land on the leaf it lands on her net instead, and she is quick to grab it. Bring a light with you some time and have a look in your garden at night; you are likely to find N. walckenaeri.

Her webbing isn't sticky. She is what is known as a cribellate spider. That is, she has among her spinnerets a sort of plate called a cribellum. She exudes silk in myriad extremely fine streams through the cribellum's countless tiny jets. As the silk emerges and hardens in the air, she combs it with a line of spines called the calamistrum into a tangled fluffy mass. Though it is not adhesive, it acts as the loops on a piece of velcro; the little spines on her prey's legs act like the hooks, and so the prey stays still long enough for her to ensure dinner. The picture above was shot through a gauzy film of this webbing.

Incidentally, the beautiful orb nets one usually thinks of when somebody says 'spider's web' were once thought the pinnacle of spider evolution. These are made by ecribellates, that is, spiders without cribella that rely on sticky silk (mostly, anyway; the highly interesting Uloboridae, a spider family that lacks venom, make cribellate orb webs). In fact, it's now thought that the orb web is ancestral to the web-building spiders; that the (superficially) disorganised and amorphous nets of other web-builders are subsequent developments; and that possession of a cribellum is the ancestral state. (And you can just imagine how that shook things up in spider systematics.) This new way of looking at things is based on molecular studies, but if you get an ecribellate, flip her over and have a good look at her backside, you might well see a wee bump called the colulus, the vestigial remnant of the cribellum her ancestors possessed long ago.

Friday arachnid blogging

Last Friday we looked at Ph. phalangioides, a spider so common that one is likely within, say, 10 metres of you as you read these words. Today, let's look at a spider that's probably a lot farther away, unless perhaps you live in the western Mediterranean basin. And the thing is, I can't even tell you exactly what she is.

Ain't she grand nonetheless? Look at her heavily sclerotised prosoma* - armoured like a tank!

What I can tell you is this: she's one of the Gnaphosidae. Had I chosen to spin her round to photograph her bum rather than her face, you'd see the large, cylindrical spinnerets characteristic of that family. I do think that, within this family, she's from one of the genera Gnaphosa or Drassodes, and probably the latter. But I don't have a good key for the Med, and I really can't say. (But hey, if she looks familiar to you, by all means let me know what you think.)

She's dead, I'm sorry to say. She came scuttling up onto the verandah as I sat in front of the bungalow one night in the Illes Balears; to her misfortune, I noticed her and arranged for her to scuttle her way right into a little glass phial. I will be back there in April and hope to see more of her kind, and with any luck to watch them going about their business on the stony fields, not on my verandah.

* I.e., her front part. Sometimes called the 'cephalothorax', meaning head-and-chest. The back bit is called the opisthosoma; again, especially in older texts, it's sometimes called the abdomen.

Friday arachnid blogging

As I mentioned when I introduced P. mirabilis, spiders are not thick on the ground at the moment, with the exception of dependable old Pholcus phalangioides. Although she is often called the 'daddy-long-legs-spider', you should not confuse her with the opilione (another sort of arachnid) or the crane-fly (an insect), each sometimes given the same name. You can tell these apart from the spider quite easily as the former lacks the spider's 'wasp-waist' and the latter has wings.

Ph. phalangioides has grown used to living in and on man's dwellings and by now I suppose you will find them nearly everywhere. There are likely a few in your cellar right now. So, if you want to see something cool, go down and find one. Then stick your finger right into her web. If it would make you less nervous, you may use a pencil, but she cannot and will not bite you. In German this species is sometimes called the Zitterspinne, the 'shivering spider', and now you can see why: she grabs the strands of her webs and vibrates into a blur, becoming virtually invisible.

If you are lucky, you will see a female while she is carrying her eggs. These are a tiny mass of coral-coloured balls that she holds between her 'teeth' in a frail gossamer net, like a little old Russian lady carrying her purchases in an avos'ka. Keep an eye on her and soon enough you will see her carrying a little ball of babies before they disperse.

I told you that Ph. phalangioides cannot bite you, and it is true. Her 'fangs' (chelicerae) are tiny. But look at them under a good microscope if you get the chance; they are fascinating. Much more than those of other spiders, they retain some vestige of the original form of the chelicerae, jointed pincers with a 'thumb' opposed to a 'finger', that you still see on the face of the spiders' cousins the scorpions and solpugids.

Some people think this spider has a particularly dangerous venom, fatal even to humans. This is not so. She may owe her reputation to the fact that she is an amazingly voracious predator of arachnids and other arthropods much bigger and bulkier than she is. She will routinely kill and devour even the hulking house spider Tegenaria atrica if one is so foolish as to come near her. If you read German and can get your hands on the Arachnologische Mitteilungen Nr. 22 of October 2001, you will find in H. Uhlenhaut's 'Beobachtungen zum Beutespektrum von Zitterspinnen (Pholcidae)' a dispassionately observed and chilling account of mass arthropod slaughter by a handful of Ph. phalangioides in a disused jakes in the house of Mr Uhlenhaut's mother-in-law.

By the way, the fellow in the picture above is just that - a fellow. You can tell by the bulby affairs just before his 'face'. These are his pedipalps; if you want to know what he uses them for, see here.

Friday arachnid blogging

As promised, here's another gorgeous creature that you won't find at Calpundit.

This is Pisaura mirabilis, caught as she rested on a leaf in the middle of a bush. That's not a pea she's holding, but her egg sac. This she carries round with her for a couple of weeks before placing it in a silken tent in which her young will hatch.

You might think it odd that P. mirabilis would be lugging her egg sac around at this time of year, and you'd be right. Until spring comes, I'll be showing pictures I've taken at various times in the past. Otherwise Fridays would, for the time being, see little more than the Pholcus phalangioides living in our cellar. Splendid little things they are, to be sure, and deserving to be shown themselves. But not perhaps every week.

A hottie

Just look at those gams! Here is Philodromus sp., whom to our great surprise we found crawling on the ceiling a few weeks ago:

From her size I suspect she was a juvenile (though if so, what on earth was she doing here at this time of year?), which makes it even harder to identify her specifically. To the naked eye she appeared almost black; the photo (taken with my patented Wretchedly Bad Jury-Rigged Macro system) reveals her full colours. She spent a few days with us, then wandered off to wherever spiders wander off to in mid-winter. (I.e., she didn't end up in a little phial of alcohol, something spiders of my acquaintance have a tendency to do.)

From time to time I'll put up snaps of spiders and other wee beasties, if they're good-looking and the photos turn out at all well. Not as cuddly as Kevin Drum's 'Friday Cat Blogging' perhaps; but if it's cuddly you want, you've come to the wrong shop.