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.

Silk spinner

If it weren't for cold, rainy days, my computer files would be a complete mess. Good thing it rains here a lot!

Sorting last year's photos today, I looked at two spider photos from Oyster Bay last October. And I noticed something I didn't see at the time: in one of the photos, the spider mama is showing off her spinnerets!

Spider, egg case, sowbugs on the bottom of a log.

I had turned over this log to see what was hiding. And besides the usual sowbugs, there was a large spider's egg case, with the mother standing guard. But she decided I was too big to challenge, and ran away. I got her photo as she left.

See the spinnerets? Tiny, hair-like tubes protruding from her rear.

Spiders produce their silk from these spinnerets; according to the species, they may have from two to four pairs, each producing its own specialized silks. From this photo, I think Ma here has either two or three pairs of spinnerets.

Spider silk has many uses, and each variety of silk has its own special qualities. Even for the common orb web, the spider 

"... pieces together a minimum of four types of silk, each having a different form and function. One silk provides strength, another flexibility, and still another a scaffold to aid the spider during construction." (from "Spider Silk: Evolution and 400 Million Years of Spinning, Waiting, Snagging, and Mating"

But there are more things to do with silk, it makes a warm blanket for spider eggs and spiderlings. It serves as bungee cords, waterproofing, rappelling rope, wind catchers for ballooning spiderlings, cords for snagging, trapping, wrapping, toting prey. Den liners and trap doors, bubbles for underwater living, distant warning systems, gift wrapping ... the uses are endless.

And do the spiders make art? Do they know the beauty of a dew-laden orb web? Does a cross spider sit back and look at her web and feel a justified pride? Who's to tell?

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Si no fuera por los dias de lluvia, los archivos de mi computadors estarían una maraña imposible de desenredar. ¡Un beneficio de este clima!

Hoy, mientras llovía encima de la nieve de anoche, revisé fotos del año pasado. Viendo fotos de octubre, tomadas en Oyster Bay, me di cuenta de algo que no había notado en ese momento. En una de las fotos, una araña madre nos enseña sus hileras.

Fotos: primero, la araña como la encontré cuando volteé un tronco en el suelo; la araña, su saco de huevos, y un grupo de cochinillas.

Había volteado el tronco para ver que manera de cosas escondía y sorprendí esta madre cuidando sus huevos. No se sintió capaz de enfrentarme, y se escapó, no sin que le sacara la foto desde atrás.

Segunda foto; ¿Ves las hileras? Son tubitos miniaturos que se abren desde el final de su abdomen..

Las arañas producen su seda a partir de estas hileras; según la especie, pueden tener de dos a cuatro pares de hileras, y cada uno produce sus sedas especializadas.

Esta seda tiene muchos usos diferentes, y cada variedad tiene sus aplicaciones especiales. Hasta para la telaraña en espiral, la araña ...

"teje juntos un mínimo de cuatro tipos de seda, cada de las cuales tiene forma y función diferentes. Una seda provee fuerza, otra flexibilidad, y otra se usa como andamio para ayudar durante la construcción. (Del libro "Spider Silk: Evolution and 400 Million Years of Spinning, Waiting, Snagging, and Mating")

Pero hay más. La seda puede formar una cobija calientita para los huevos y las hijas arañitas. Sirve como cuerda de bungee, impermeabilización, cuerdas para montañismo (en miniatura), atrapavientos para arañitas que van volando para encontrar un nuevo hogar, cuerdas para cazar, capturar, envolver, cargar su presa. Recubrimiento para las paredes de su cueva o túnel, puertas escondidas, sistemas de burbujas para vivir bajo el agua, sistemas de alerta distante, envoltura para regalos ... Hay mil y un usos.

¿Y será que las arañas producen arte? ¿Conocen la belleza de una telaraña en espiral llena de joyas del rocío del amanecer? ¿Será posible que una araña Diadematus se echa para atrás para mirar su telaraña, sintiendo un orgullo bien justificado? ¿Quién puede saber?

Arachtober 9: the reader

I've been following this little jumper around with the camera for days. When I took this, he was visiting my bedside table; now he's on my dresser.

He's tipped back, gluing a tracking webline to the book.

Jumpers are not cobweb builders, but they do travel at the end of a silk line, which enables them to drop and dangle off a "cliff" or the edge of my bedside table, in this case. They also make themselves safe spaces, silk shelters under leaves or the loose bark of a tree. One (not the bookworm) has build himself a hammock in the corner of my ceiling today and appears to be resting there.

#Arachtober

Hanging by a thread

10:30 at night. I went to draw my curtains, and found a small moth sleeping on the outside of the window. Grabbed the camera, dragged over a chair, climbed up, got one shot of the moth.

Lucky shot. Because there was only one.

And the cat scrambled through the window, disturbing the moth, who fluttered directly into a spider web. Instantly, the spider appeared from nowhere, pouncing on the struggling moth.

Happy cross spider, unfortunate moth.

And in a couple of minutes, the moth was quiet, and the spider was covered head to toes in moth feathers.

She hangs from two threads; one paid out from her spinnerets, and another she's holding with one rear foot.

Zooming in on the spinnerets. The silk turns out to be a bundle of very fine threads.

Web and wall

At the fish ladder on Woodhus Creek, a spider takes advantage of the summer drought to build her web.

Cement, rocks, and fine silk, catching the sunlight. The spider is there in the centre, dazzling white in the afternoon sun.

So fragile, that web; I can brush it away with a finger; a frantic wasp can tear a great hole in it. And yet pound for pound, it's stronger than the rocks beneath, stronger than the heavy concrete wall.

And at the end of the day, the spider will eat it, and reprocess it for tomorrow's web.