Wanna see a bag of spiders?

I’m afraid no one will, and that makes me sad. They’re so cute! They’re like a bunch of puppies, all awkward and bumbling, stumbling out of the egg sac to try and figure out this messy ol’ world. So I made a video of Steatoda triangulosa spiderlings that, like my usual spider videos, will flop. I don’t quite know what to do about that — I’ve got to carry out a world-wide campaign to readjust everyone’s attitude towards spiders.

So I made my video into a YouTube premiere. You won’t be able to watch it until 7pm Central tonight, and I think the idea is to build a little anticipation and promote it before it’s available, as if maybe people will tune in expecting something more than 20 minutes of baby spiders.

Surprise. It’s 20 minutes of baby spiders. I simply can’t hide the truth.

Check it out in about 12 hours. They’re lovely and will melt your heart, if you give them a chance.

Still waiting…

Checked on my collection of S. triangulosa egg sacs this morning. The one I’ve been waiting on for 27 days hasn’t yet opened up, but it looks distinctly different — it’s a black mass with little hairy black legs poking up, surrounded by cottony fluff. The spiderlings are making me wait longer. I was tempted to pull out my forceps and extract them by force, but I’m waiting to see what the normal developmental time at 28°C might be, so no shortcuts allowed. Any day now, as I’ve been saying for a week.

Then I checked on their momma. I’ve moved her into a separate, larger container now, and the other day I fed her a big juicy mealworm…which immediately thrashed it’s way out of the web and fell to the container floor. The web was pretty much shredded at that time, and I couldn’t stick the worm into it, so I left it there and figured I’d move it today, when the web was repaired. Usually, Parasteatoda ignores food that doesn’t land in a web, and I figured she’d be the same. They’re rather passive predators.

I was wrong! S. tri is willing to get down and dirty, had dived in snared the mealworm, and then hoisted it about 10cm up. It was dead, dangling, with a black ring in the segment that the spider had bitten and sucked out its juices.

Good work, mom. Then I sought out the spider, who was now nearly spherical again. I’ll spare the arachnophobes that image.

Then, to my surprise, she had spent last night laying another egg sac!

That’s 5 in 4 weeks. I’d wondered how they kept their population up compared to P. tep, since their egg sacs hold a fifth the number of spiderlings. There’s the answer: they make it up in volume.

Pacing about in the waiting room

I was sure today would be the day. As soon as I got out of PT, I rushed over to the lab, confident that finally my Steatoda triangulosa spiderlings would be emerging. Yesterday, I saw that they were getting dark hairs on their legs, although their bodies remain pale, and were making occasional feeble twitches, so I figured they’d be getting on with it shortly.

No such luck. The legs are getting darker, and the movements are much more robust. They’re packed tightly into the egg sac, so when you see one wiggle, there’s a wave of activity all across the sac. Any time now, he says again, as he has for the last several days.

Part of the reason for my eagerness is that I’m used to Parasteatoda — the spiderlings of that species emerge after less than 10 days, while these S. trangulosa eggs/embryos have been sitting there developing for 26 days so far. And P. tepidariorum will hatch out as many as a 100 babies at onces, while this species’ egg sacs will produce maybe 20 spiderlings. No wonder P. tep is the popular model system!

It makes me wonder how they can compete. P. tep is ubiquitous in houses; S. tri I find in houses, but also in ‘wilder’ environments. Maybe they’re simply being outcompeted for the most stable environment, or maybe S. tri spiderlings are better adapted, somehow, for more marginal spaces. I don’t know. I’m going to have to hatch out some P. tep and have them wrestle.

I’m also going to have to get some S. borealis egg sacs for comparison, but they’re turning out to be harder to breed in the lab.

I’m recording some day-by-day videos, and when the whole batch finally pops out, I’ll compile them all together and post them on YouTube…but I’ll be releasing them to my Patreon first.

Spider mating habits can repair ignorant slanders against Darwin

I don’t know about this Salon article, “A microscopic evolutionary arms race is happening between sperm”. It’s OK, but it put me off in the introduction.

As world-enlightening as Darwin’s ideas of natural and sexual selection were, there’s a tiny whiff of failure about him as a scientist. Brilliant as he was, he never realized that natural selection and sexual selection aren’t quite enough to explain evolution.

That’s just wrong. He didn’t get everything right, and he certainly didn’t explain everything about evolution, but he was humbly self-aware of that fact. There is no “tiny whiff of failure” associated with a scientist failing to explain the totality of evolution. If that were the case, every scientist ever would reek of failure. That passage reads more like the author is surprised by new discoveries in the field, and is projecting her own disappointment that a single book from 1859 was not comprehensive.

Also, nothing in the article is a new discovery. Sperm competition has been a known phenomenon for at least as long as I’ve been a biologist. There was a long-running aversion to the whole concept of polyandry, thanks to Darwin’s Victorian heritage, and I’m sure you can find some old relics in universities somewhere who want to think that sexual selection is all about brawny masculinity battering any competition into submission, but that’s just not the way most species work.

The author redeems herself at least in part by discussing spiders.

Perhaps because they’re easy to catch and breed, much of the research about sperm competition has been done on spiders. February 2022 work from biologists at Ludwig Maximilian University in Munich and Aarhus University in Denmark shows the benefit to mating males of long copulations. When a male nursery web spider (species Pisaura mirabilis, found all over Europe) offers a female a “nuptial gift” of a silk-wrapped bug, she allows him to copulate. What’s more, she lets him continue to flood her receptacle with sperm for as long as the proffered meal lasts. In an email, co-investigator Dr. Cristine Tuni explained the logic of this adaptation. The spider’s ejaculate doesn’t arrive as a brief, happy burst and then stop. Rather: “In this species, sperm is transferred continuously over time from his copulatory organ into hers,” Tuni says. “So, the longer a male has his organ coupled to a female organ, the more sperm is transferred. The relationship is basically linear.”

One egg sac can carry hundreds of eggs. Because of this, any male wanting a big bang for his f**k probably intuits that size (of the gift) matters. Pumping as much semen as possible can help send his DNA on its way.

Malabar spiders
The Malabar spider (Nephilengys malabarensis, found in Asian rain forests) wields a far more dramatic sperm competition adaptation. Each male has two genital appendages extending from behind the mouth. As semen pulsates out of one, the spider detaches it and leaves it inside the female’s receptacle. Even severed like that, the genital continues to ejaculate. Meanwhile, it also plugs the receptacle, making it difficult for another male to get a genital in. Ready to fend off anyone who tries, the mating male stays on the web near the female. Unfortunately for him, each female’s semen receptacle has two openings. He has only plugged one. This means that, if a rival approaches, the mating male will have to fight fiercely to keep him at bay. To that end, and while ejaculation from the abandoned genital continues, many males eat their only remaining genital.

Of course, that seems like a counter-intuitive strategy. Why get hungry at that very moment? Why hurt yourself right when you may need all the energy you can muster?

A team of biologists from several institutions in Europe and Asia seem to have an answer. They compared the battle survival rates of spiders who’d severed one genital to those of spiders who’d severed one and eaten the other. Additionally, they tested the battle survival rates of genitally intact males. The name of the team’s paper — “Eunuchs Are Better Fighters” — says a lot about why, under duress, a Malabar spider would eat its only remaining genital.

But what a way to go.

Unfortunately, it doesn’t discuss one of my favorite peculiar spider mating habits. Dark fishing spider (a common species in my area) males, once they succeed in mating to the point where they’ve inserted one palp into the female’s epigyne, spontaneously and abruptly drop dead. The palp is locked in place and the corpse continues to dribble sperm, but the poor guy is totally deceased, and eventually the female will notice the small dead male’s body dangling from her genitals and eat him.

Remember those horrible 80s comedies that were obsessed with teenagers desperate to lose their virginity? I like to imagine the obnoxious male protagonists having all the sexual properties of Dolomedes.

We got legs!

I am excited to report that the latest generation of spiders in the colony is developing nicely. Here’s a closeup of a Steatoda triangulosa egg sac, and you can see the adorable little spiderling embryos inside. There are legs! Eight of them! Everything is looking good.

A lot of you don’t like spider photos (cute baby spiders don’t count, right?), but you can see those on Patreon. She’s out of focus in this one, but as soon as I put the optics on that egg sac, she scurried over and maternally embraced it — she’s the loving darkness lurking in the deep blur behind the eggs you see here.

How a spider eats

This video has been online for 9 years, and only has 358 views. That’s sad. Maybe it has something to do with the subject?

If you’ve wondered how spiders eat, they have a pair of chelicerae in front of their face that are used for injecting venom/chopping up prey, but they’re not for ingestion at all. They have mouthparts behind the chelicerae, which they then use for sucking up fluids and spitting up more saliva. The video is a closeup of a prey animal with a rather translucent exoskeleton, so you can actually see the juices sloshing around inside and being sucked out. This is cool; fruit flies don’t show much, there is only a small amount of bug goo inside, but I have seen mealworms get their guts literally drained out of the exoskeleton, leaving nothing but a hollow shell when the spider is done.

I can guess why this is an unpopular video, so I’ll hide it below the fold.

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Yay! Egg sac!

If you’re on my Patreon, you already knew about my little catastrophe: one of my Steatoda triangulosa had produced a beautiful fluffy egg sac, I’d rewarded her by feeding her a mealworm, and in the ensuing struggle, the eggs had been smashed. Mama Triangulate Combfoot had her vengeance, and sucked that mealworm dry, reducing it to an empty husk. But the eggs were demolished.

Well now she’s gone ahead and produced a brand new egg sac. Look at it, it’s beautiful.

These look very different than Parasteatoda egg sacs, which are finished off with a light brown leathery casing, but they’re both the same otherwise — a nice wooly blanket of spider silk suspends and cushions the eggs inside. Now begins the pregnancy watch, with hatching expected probably next week sometime.

The Great Spider Heist

One of my colleague has a lovely compost bin in their back yard. Or should I say, “had”. They’re leaving our fair campus for a new job in the big city of Madison, which caused me some worry — not just for losing a good contributor in the science & math division, but because, as I’ve reported before, their compost bin has a magnificent colony of Steatoda borealis thriving inside it. Nobody ever asks, “what about the spiders?” when they leave.
So Mary and I…ummm…”appropriated” the compost bin. Don’t worry, I asked permission first, and it has now been relocated to our yard. Just outside our door, where I can check on them regularly.
Is it not beautiful?

It was a disruptive process for many of the spiders. The bottom is open, so hoisting it up meant losing much of the compost inside, but we shoveled up much of it and restocked the bin. No doubt we lost some spiders in the move, but they mainly live in the tangle of webbing inside the lid, not in the compost itself. Lots of egg sacs were still there.

And of course, many agitated spiders scurrying about on the lid.

They live on the small insects that emerge from the decaying compost, and survive the winter on the warmth of the fermenting organic matter, so I threw in some old potatoes I’d been saving for this occasion. We’ll also be much more careful to toss food waste in there, to keep the spiders happy.
We’ll also rename the bin the Atkinson Home for Hungry Spiders, in honor of my colleague.
Although, I don’t understand why he didn’t want to pack up such a gorgeous box full of joy to bring to his new home.

This story has also been posted to Patreon, and I’ll post occasional updates on the status of the happy spider family there.

Spider battles a wasp!

I know a lot of people here dislike spider photos, but this is a video, and it’s a battle between a handsome Steatoda and a much larger wasp. Usually wasps win these kinds of fight, but not in this case, which made me happy.

Also, watch the spider pause once the wasp is lethally envenomated, step towards the camera, and preen for a bit before going back to hog-tie the beast. Bravo!

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