Spider on a bungee cord

I've been sharing my house with a spider. I'm raising fruit flies for her dinners, shooing away cellar spiders who would like to horn in, making sure her web stays undisturbed. Why? Because she's beautiful, for one. And she's obviously a politer housemate than the cat; she doesn't walk on my keyboard or try to steal my food or trip me up when I'm cooking. Or leave hairs on my furniture. She's just there, building her daily web, eating fruit flies, hanging out ...

Araneus diadematus in my window.

I've been watching her, and I've noticed something that I wouldn't have seen, coming across her web in the woods or strung over my front door. See, she hangs in the centre of her web, head down, without moving. For hours, if no flies touch the web. And then I shake up the fly container and a handful lift off. One, or sometimes a few, will land up on her web. She thinks about it for a minute or two; sometimes a fly will struggle for a couple of seconds and then escape; no sense chasing it. Then once the fly is well tangled, she runs down (or across) the web, grabs the fly, wraps it up, and ...

Then she just lets go, and swings from the dragline she spins everywhere she goes. Swings. Away from the web; she's no longer touching it. And instantly the line contracts, drags her back to her observation post. No effort on her part; no scrambling along the web; just letting go. So sudden is her return that the whole web bounces back and forth.

It's as if she were on a bungee cord.

Here she is with several flies. I've seen her collect up to 5 flies in one collection run.

I started to wonder: is that how it works? The silk thread is elastic? Or does the spinneret retrieve the silk it just spun out? I looked it up. No, silk, once produced, is only recycled when the spider eats it. So how elastic is this silk?

Biologists have been looking into it.

Spider silks are made from proteins, and biologists have just discovered that the secret lies in the silk protein's amino acid content. Spider silks with high proline contents behave like elastic rubber bands, while spider silks with low proline content behave like stretchy springs. ... Araneus (diadematus) silk is relatively rich in the amino acid proline. ... (It) contains 16% proline, found mostly in linker regions between the protein's crystalline structures, which would make the linkers flexible and randomly arranged. ... For the proline-rich Araneus (hydrated) silk the force varied in direct proportion to the temperature, behaving ... like floppy rubber bands. (From the Journal of Experimental Biology. "Spider Silk Can Be Stretchy Like Springs Or Like Rubber." ScienceDaily. ScienceDaily, 5 June 2008.)

So my window must have the right temperature and humidity for silk bungee cords. And the right species of spider, too.

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En casa tengo otra compañera; una araña. Estoy criando moscas de la fruta, Drosophila sp., para darle de comer, y espantándo las arañas fólcidas que tratan de aprovecharse. ¿Porqué? Pues, es hermosa; esa es una de las razones. Y se porta mejor que la gata; no pasa caminando encima del teclado de mi computadora, no trata de robar la comida de mi plato, no me hace tropezar en la cocina. Y no deja pelos en los muebles. Nada más se queda quieta, construyendo su telaraña a diario, comiendo las moscas, esperando ...

Foto: Araneus diadematus en su telaraña en mi ventana.

La he estado observando, y me he dado cuenta de algo que no hubiera visto al encontrarla en su telaraña en el bosque, o extendida enfrente de mi puerta. Se cuelga en su telaraña, con la cabeza para abajo, sin moverse. Hora tras hora, mientras ningún insecto toque su red. Y luego sacudo el botecito donde viven las moscas y algunas se echan al aire. Una, o tal vez algunas, terminan atrapadas. La araña lo piensa unos minutos; a veces una mosca logra escapar y no vale la pena perseguirla. Una vez bien enmarañada la mosca, la araña baja corriendo, agarra la mosca, la envuelve en seda, y ...

... se echa al vacío, colgada solamente del hilo de seda que va formando al caminar. Se cuelga, libre. Suelta la telaraña; deja todo contacto. E instantáneamente el hilo se contrae y la arrastra hasta su base en lo alto de la telaraña. No hace ningún esfuerzo; no toca la seda con las patas; solamente se deja colgar libremente. Y tan repentino es su regreso que toda la telaraña vibra.

Es como si se hubiera saltado con una cuerda de bungee.

Foto: aquí tiene varias moscas. La he visto juntar hasta cinco para una comida.

Me hizo pensar. ¿Cómo funciona eso? ¿Será que la seda es elástica? ¿O es que las hileras vuelven a absorber la seda que han producido? Busqué entre sitios web; no, una vez extraída la seda, solamente se puede reciclar cuando la araña la come. La seda tiene que ser elástica. ¿Pero, tanto como una cuerda de bungee?

Los biólogos lo han estado estudiando.

Las sedas de las arañas están hechas de proteínas, y los biólogos acaban de descubrir que el secreto reside en el contenido de los aminoácidos de la seda. Sedas de araña con contenidos altos de prolina se comportan como bandas de goma elásticas, mientras que sedas de arañas con contenido de prolina bajo actúan como resortes. ... La seda de Araneus (diadematus) es rica en el aminoácido prolina. ... Contiene el 16% de prolina, que se encuentra por la mayor parte en regiones que unen las estructuras cristalinas de la proteína y haría los vinculadores flexibles y organizados al azar ... En la seda ... (hidratada) ... rica en prolina de las Araneus, la fuerza variaba en proporción directa a la temperatura, comportándose ... como bandas de goma flexibles. (Del Journal of Experimental Biology. "Spider Silk Can Be Stretchy Like Springs Or Like Rubber." ScienceDaily. ScienceDaily, 5 June 2008.)

Parece, entonces, que mi ventana ofrece justo la temperatura y la humedad óptimas para cuerdas de bungee de seda. Y que también estoy hospedando la especie correcta de araña.

Greedy, part Three (procrastination edition)

I'm still sorting forgotten photos.

First, the backstory: In September of 2018, I was suffering a plague of fruit flies, come to feast on the apples in my yard. A pretty cross spider had set up her web in a doorway, and I was happy to leave her there; she was helping out with the fruit flies. I named her Patience, because she sat there for days without moving.

I posted her photo at the end of August; she had caught one fly, tied it up, and gone for the second, which she hauled back and tied up with the first before she settled down to eat.

A week later, she caught 6 flies and tied them all up in one bundle.

Then I was busy; school had started, and I had time to take her photo again, but no time to process them. They've been sitting on my hard drive ever since.

So here's the next in the series:

Patience, with a humongous, densely packed ball of fruit flies.

She had abandoned her web in the doorway and moved down, closer to the bowl of apples on my table.

Hauling them off to a corner to eat them.

Close-up of her back

She's called a cross spider because of the pattern towards the front (bottom here), but she could also be a pagoda spider by the rest of the art. In Latin, she's Araneus diadematus: a crown spider.

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Sigo revisando fotos olvidadas.

Primero; la historia. Hace año y medio, en septiembre de 2018, sufría de una plaga de moscas de fruta, porque los manzanos alrededor de mi casa estaban llenos de fruta. Una araña bonita "diadematus" se había instalado en una esquina, con mi aprobación porque ayudaba con el control de las moscas. Le puse el nombre de "Paciencia" porque ahí esperaba, dia tras dia, sin moverse.

Al final de Agosto, le saqué unas fotos: había cazado una mosca, la había atado, y luego fue a cazar la segunda, la cual trajo a amarrar con la primera antes de sentarse a comer.

Una semana más tarde, capturó 6 mosquitas, y las amarró todas juntas en una bola.

Después, yo estaba ocupada; había empezado el año escolar, y aunque saqué unas fotos, no tuve tiempo de procesarlas, y allí han estado olvidadas en la computadora hasta ahora.

Bueno, aquí están, for fin:

Había abandonado su red en la esquina, y se mudó más cerca al plato de manzanas en mi mesa. La encontré con una pelota enorme de muchas moscas de fruta.

La última foto muestra el diseño de su abdomen. Se llama, en inglés, una araña de la cruz, por las marcas hacia el frente (parte de abajo de la foto). Pero también se le podría llamar una araña de la pagoda china, por el diseño completo. En Latín, se le llama Araneus diadematus, o sea, araña de la corona.

Knees up, Mother Brown

I've spent several hours over the last three days just trying to take a photo of one spider. She's set up her web in an antique cabinet on my wall, where I can reach her easily. But she's too smart for me.

Cellar spider, Pholcus phalangoides. More legs than spider.

These spiders spin long, fragile, almost invisible lines of silk, in no particular pattern, stretching far from their resting place. I see patches where they have caught prey here and there, but most of the lines seem to be a warning system. So the problem with taking her photo was that as soon as I got anywhere near, she went into hiding. Even cautiously positioning my flash attachment a foot away, with no other movement, made her leave.

When the flash hits her directly, she looks grey. In normal light, she's pale brown.

Or maybe she decides not to run away. She has another strategy: a touch on her web, far away from where she waits, and she begins to dance. She vibrates and spins rapidly, too fast even for my old eyes, let alone the camera.

... And whirling round and round. Whirling round and round. Whirling, whirling, never twirling. Whirling round and round. (From children's version of "Knees up, Mother Brown".)

Setting the camera on autofocus sometimes works, if the background is right. Otherwise, since the spider is so pale, the camera decides I want the wood grain, or the leftover bits of web. With manual focus, I have to get close enough to see what I'm getting, and by then, she's gone. She's in cahoots with the camera.

This afternoon she moved to a spot where I could insert the camera and one hand, but couldn't see my screen. And the flash was already set up aiming sort of that way. So I set the camera on manual focus and took almost 100 blind shots; something would work, I hoped.

I got knees.

Knees up, Mother Brown

And hairy legs.

And shiny eyes.

It seems that the patterns on her abdomen are not on the surface, but the internal structures, seen through a traslucent skin. I'll have to find another one and take more photos to confirm this.

Greedy, Take Two. Or Six.

A week ago I posted the story of a spider and her fruit fly dinner. She had dashed from one end of her web to the other within seconds to catch two flies at once. I wondered then, what would happen if I gave her three flies.

Last night, I took the lid off the fruit fly trap beside her web, and this time a half-dozen flies were caught.

The spider leapt into action, took two steps and stood there, frozen, confused maybe by the signals coming from all sides. She thought about it for a few minutes, then went slowly over to the nearest fly, grabbed it and wrapped it up.

Then she left her dinner hanging, and went for the next, brought it back and wrapped it with the first. Rinse and repeat: she caught all 6 fruit flies and bundled them together before she settled down to eat.

Big meal. The red colouring is fruit fly eyes; 12 of them.

So that question is answered.

Greedy!

The apples on the tree outside my bedroom window are ripe and dropping on the ground. I've collected several bowlfuls for eating, made a batch of applesauce, and baked a few with oatmeal crumbles. The compost bin is full of apple cores, and the house is full of fruit flies.

I've trapped many, but there are always more. And now my corners are full of tiny spiders getting fat on fruit flies. I appreciate their help.

Fruit fly on the kitchen wall.

A few of the apples, with the few fruit flies that didn't leave when I approached.

Fruit flies on a blemish on an apple.

A small cross spider, Araneus diadematus, has built herself a web in a handy location (for me) just at eye level by the kitchen entrance, and seems to be a bit bigger every day. I caught her two days ago with a mouthful of fruit fly:

She's so handy I can even measure her without disturbing her. She's 7 mm long today.

 I've set up a fruit fly trap, which did reduce the airborne population a bit, but then I decided to feed my friendly cross spider. I took off the lid an inch away from her web, and two fruit flies hit the web immediately. Instantly, half a second or less later, Little Miss Patience, here, had dashed across the web and caught one of the flies. As expected.

What surprised me was that now, with her fangs full of fruit fly, she dashed to the other end of the web and grabbed the second fly, then returned to the centre carrying both of them. Which she tied up in one little bundle and settled down to eat.

A veritable feast; a two-fruit-fly taco!

When I came back a few hours later, there was no sign of the flies. The web was clean and repaired, and LMP was sitting in the centre, waiting again.

And the rest of the flies from my trap were loose; they're even perching on my computer screen as I work.

I wonder; if I gave her three flies, would she catch all three together?

Unequal match

The sad story of Fang, Part II

Recap: I found Fang in the kitchen, took his photo, and sent him to play outside.

Why I named him Fang. He's about 3 inches across, toe to toe.

These warm days, I do a "bug run" every day just outside my door, finding mostly spiders; house spiders, cross spiders, crab spiders, and the occasional wanderer, like Fang. (Usually much smaller, though.)

Cross spider in her web. 10 PM; these ones work night and day.

Yesterday evening, there was a new one, a pinhead-sized white spider. I had to set up the tripod to get a photo; the web was dancing with every tiny breeze, and there was no leeway for an additional shaking hand. I had to move a few plant pots to set up the tripod, and Fang came running out from under one of them. I shooed him off, away from where I would be standing.

Tiny

I got my photo, and was heading back inside, carrying the camera still attached to the tripod, when I saw Fang on the wall, below the web of one of the fat web spiders I've been watching. He was facing the proprietress of the web; she was darting in towards him, then backing off in a hurry.

And his fangs were as long as her entire body! This was not going to end well.

In the few minutes that I took to re-position the tripod, the situation had changed. Fang was sitting quietly, while Ma G. (for Gordita) was poking at his legs.

He's still threatening her with those big fangs.

She'd found his weak spot; she went around and around him, systematically stinging the joints in his legs, where he has a flexible membrane, rather than the hard exoskeleton.

Spiders extend their legs using hydraulics, rather than muscles, as we do. To run, they increase the pressure in the cephalothorax (the head/upper body section), sending blood down the legs. Small muscles then return the liquid to the body, returning the legs to the relaxed position. So a shot of paralyzing poison to the legs soon invades the whole body.

Biting his knee. He's settling down, now.

Once he was still, she started to work on tying him up, starting at the legs, then running over and under the body, until he would be unable to move even if the poison stopped working. She paused, a couple of times, now that he was immobile, to sting the underside of his belly, another weak spot.

He has extruded what I presume is a blob of silk from the spinnerets, in his death throes.

Once that was done, she returned to her usual spot at the top of her web, and slowly winched him up until she could anchor him in her dining room. It was slow going; he was heavy and ungainly. It was getting dark, and I left before she'd finished.

I came back just before dawn to see what was going on. She was busy eating.

She's used a lot of silk, tying up those long legs. She'll eat it again, when she cuts him loose. Spiders recycle!

The lure of plastic

A male Philodromus dispar spider moved into my spider house while it sat outside with the lid open, airing out. I closed it up and brought it in, but after a couple of days, the spider was unhappy with the arrangement. He kept running and running and running, never stopping, for hours. Looking for a mate, I guessed, and opened the top for him. He scampered up and out; I let him go.

On my desk, there's a plastic bottle of aerated water that I use to spray critters that need to be kept damp. When next I saw "Philo", he was climbing up the bottle. When he got to the top, he stopped abruptly, put his pedipalps down against the plastic, his rear in the air, not a customary pose for these active spiders. And then he just stayed put there, as though his pedipalps had been glued down. I shooed him along, and he moved an inch or two and repeated the pose, pedipalps to the plastic.

"Interesting stuff! Smells like ..."

He's a mature male, shown by the large "boxing glove" ends on his pedipalps*; he uses these to transport sperm to the female's genital pore. But why does he want to make contact with this particular plastic? Is there some chemical in the plastic that reminds him of a female's pheromones?

Now that I think of it, was it the smell of the plastic, just outside his house, that drove him frantic in the first place?

Questions, questions. I haven't found an answer.

After a bit, since he wouldn't leave the top of the bottle on his own, I shook him off by the outside door. In the morning, I found him on a vinyl chair in the kitchen.

*Alex Webb has an astounding photo of a male black widow's pedipalps; go take a look!