Another week, another data point

I’m still regularly collecting data on growth rates in Steatoda triangulosa. Here’s what it looks like on day 39 (dark red line is the mean, I’ve included data for individual spiders in a lighter color to illustrate the variation):

They’re now at about, or over, half the adult body size, and are looking fairly mature. The palps haven’t fully matured, so I can’t sex them very well, but the ones I suspect are male — they just have a bit of a bulge — are on the smaller size. The couple that have really taken off look very female to me so far.

I’m discovering all kinds of complications, though. In particular, size is definitely a function of feeding. I gave them all a mealworm earlier this week, and some of them look hugely rotund right now. Fruit flies are definitely not adequate for the full nutrition of a growing spider, so it looks like I’m going to need to spruce up the mealworm colony soon. I’ve got another S. triangulosa egg sac that has reached the stage of seething darkness, which means I’ll have more babies this week.

Also the pigmentation is distinct and strong, and now it’s obvious that these spiders have white triangles on a dark background, rather than dark stripes on a pale background. This next batch of babies are going to require daily mapping of pigment patterns so I can see exactly what’s going on. I’m about to post a few photos on the Patreon page, if you want to see.

Spider Studio Mk. I

I’ve been struggling to document pigmentation changes in my developing Steatoda triangulosa because they’re annoyingly alive. They’ve got preferences — they like to hang upside down, they will occasionally move, they are not being obliging as far as photography goes. They’re as lovely as a supermodel, but they’re also somewhat diva-ish and uncooperative. When I tell them to pose, or spread those legs, or look at the camera, they just ignore me. It also doesn’t help that I’ve got them living in these rigid containers, and if I shoo them out into a more photogenic location they get agitated and skitter about.

So I thought of a better way to manipulate them. Behold, Spider Studio Mk. I!

As usual, simple is better. All this is is a strip of paper curled into a cylinder, held together with two pieces of tape, sandwiched between the top and bottom of a petri dish. It’s ridiculously simple. The first test was to put a spider in there and see what they thought of it. They liked it! They built a cobweb in there and were hanging there, as always, when I came in this morning. Big bonus: they seem to prefer attaching silk to the paper walls than to the plastic dishes. I simply took away the petri dishes, leaving me with a nice calm undisturbed spider hanging in a paper hoop. I could orient the ring any way I wanted without stressing the spider at all!

I took a few pictures of my test subjects (I’ll put them on my Patreon for anyone who really wants to see them). It was great. I could take a picture of the dorsal side, and then flip the ring and take an equivalent picture of the ventral side.

I still have to make a few refinements. The paper ring is a bit thicker than necessary, and it still gets in the way when oriented to certain angles, so I’ll make thinner ones. I’m also going to stick some paper handles to the outside so I can use these soldering helping hands I’ve got to hold them in place.

There’s nothing I can do to cope with these being living animals. They still like to shuffle around on their web, but minimizing manipulation reduces that.

More progress!

Another week, another data point

The data collection plods on. I’ve added body length measurements for my growing Steatoda triangulosa babies, and they’re coming along nicely. What you’re seeing here is body length in mm vs days after emergence.

They molted on day 22, which accounts for the slower rate between the 2nd and 3rd timepoint — once they shed that constraining cuticle, growth rebounded nicely.

There is some variation in the individual growth rates. The smallest baby is 2.1mm long, the largest is 3.4mm. They’ve also gotten much harder to measure, because they’re more active and get more annoyed at being put under the microscope. I had to drop two of them from this week’s measurement because they wouldn’t cooperate and lie in an appropriate orientation.

I’m experimenting now with an alternative method of keeping the ones I’m recording: I made simple paper strips in a circle, sandwiched between two petri dishes. The plan is to get them to build their cobwebs in that, and then I remove the petri dishes and have the spiders hanging in a ring that I can orient any way I want and get some more standard alignments for comparison. The poor babies hate being shuffled around, but they also like hanging stationary, so it might work — the initial manipulation might get them agitated, but then if I’m patient they’ll settle down and pose for me.

Isn’t it fun to tinker in the lab?

Where’s Alex Jones when you need someone to scream about scary science?

The word is “necrobotics” — using science to reanimate corpses. It’s still necromancy. This one lab is taking advantage of the mechanics of spider limb movements to use their dead bodies as robot hands.

Unlike mammals, which move their limbs by extending and contracting opposing muscles, spiders move their legs via hydraulic pressure. More specifically, they have a “prosoma chamber” located near their head which sends blood into the legs as it contracts – this causes the legs to extend. When the pressure is released, the legs close back in.

You can see where this is going. All we have to do is apply a little pressure and the limbs will extend, so you can just slide a needle into the chamber and presto, you can make the dead spider dance like a puppet. One thing that surprises me is how easy it is, using just a hand-held syringe to pump up the limbs.

It’s a rather gimmicky approach, and I don’t believe for a moment that it will ever have any practical applications. You’d have to murder a lot of spiders, and it sounds like they’re only going to have limited utility. It’s the same reason we can’t use zombies as Amazon warehouse workers — sure, they’d be cheap, wouldn’t unionize, and you could work them nonstop, but after a few days to a week their arms would rot and fall off.

Jeff Bezos has probably already done the analysis.

Happiness is a pocket full of maggots and spider eggs

Our compost bin is thriving! We found some new egg sacs inside it, like this one:

It’s strange. It’s orange. We suspect it might be Mimetus, the pirate spider, but time will tell. I took it into the lab and will have to wait for it to hatch out.
The other compost development is that it is full of squirmy busy maggots. I’m talking dense sheets of a multitude of swarming maggots. I scooped up some and brought them in to see if the spiders would eat them. They liked it! (The spiders, not the larvae.) This will be an alternate food source, at least over the summer. I think it’ll slow down a lot once the temperature drops below freezing.
In other news, I’ve been doing weekly measurements of the growth of my Steatoda triangulosa babies. They’re all (except one, sort of) growing well. Here’s a table of the mean dimensions of the young spiders.

I know, not exactly exciting, and I have to plod through more weeks of measurements. Note the big surge in length this week! That’s because they all molted on Day 22, and shedding that exoskeleton gave them more room to stretch.
I mentioned one spider was an exception. Spider #5 is looking a bit odd. Still growing, but suddenly their limbs and palps have gone pale…I’m hoping they’re not sick.

An important lesson

Do not make your observatory look like a giant pill bug.

That’s how you get giant spiders, you know.

Noooo! Too slow!

I’ve been tracking the growth of individuals in my Steatoda triangulosa colony, and finally have a whole 3 time points so I can estimate the spider growth rate. Behold, the first preliminary chart!

The line is a linear fit, which is not likely to be what I see in the end, but it’s optimistic, and I can’t really make many assumptions with so little data. But OK, if aiming to raise these spiders to a length of 1 meter, that’ll only take, with that assumption, about…a century? Yikes.

That rate is perfectly appropriate if they max out at 10mm long, like their mommy, but it’s going to be hard to take over the world with tiny little spiders like that. I guess I’ll have to go for numbers.

First I’ve ever heard of a food company wanting to use a spider for PR

There is a spider, Araneus mitificus, AKA the Kidney Garden spider, that sort of vaguely resembles the mascot (?) of Pringles potato chips. Surprisingly, the Kellog company, which markets Pringles, has embraced this idea and want to make the name “Pringles Spider” official.

There’s a petition and a website. If the name change is approved, which they think they can do by persuading “the decision maker” with enough signatures, the first 1500 signatories get one free can of potato chips. Who is the “decision maker”? They don’t know.

Pringles has added a petition to Change.org with the hopes that the International Society of Arachnology, the American Arachnological Society, and other organizations will “do what’s right and recognize this very real spider as the Pringles Spider.”

How awkward. The American Arachnological Society does not determine nomenclature, neither does International Society of Arachnology. You can send all the requests you want to them, and they’re just going to give you the side-eye and block you as spam. There is an International Commission on Zoological Nomenclature, but they have very strict rules about the assignment of binomial nomenclature, you aren’t going to change that. Common names are vague and often lazily defined by usage; you can call it the “Pringles spider” if you want, but it has no official weight.

There is absolutely nothing preventing Pringles from putting a photo of Araneus mitificus on all of their packaging and happily calling it the Pringles Spider. They could also make commercials with a smiling anthropomorphized spider touting their product, and get rid of the mustachioed cartoon man altogether. They don’t need a petition for any of that!

Go ahead, Pringles. I dare you. I double-dog dare you.