First thing I found: a cross orbweaver, Araneus diadematus. We haven’t found any of these where we live in Minnesota.
These are the common spiders both my wife and I remember from our childhoods.
Spiderlings are cute.
I just got my hands on Biology of Spiders by Rainer Foelix, and it’s very, very good…but beware, it’s an academic text, so the prices swing widely with the source and the edition, with some sources seeming to expect you’re sitting on a half million dollar grant so you’re not concerned with the cost. That’s not me, so I was happy to find a copy for $12 at Half-Price Books. Hooray for used book stores!
Anyway, I spent a pleasant morning starting to dig into this book. It’s technical and gets into a tremendous amount of detail on anatomy & physiology & behavior, and I was genuinely happy to see that it doesn’t get bogged down in the taxonomy wars. Only the last chapter is on Phylogeny and Systematics, and it’s short, and begins with a warning.
Now a book on biology is hardly the place to insert a chapter on classification.
W.S. Bristow, 1938
Despite Bristow’s warning, it seems necessary to cover the descent and classification of spiders briefly. I must admit, however, that our real knowledge of the phylogeny of spiders is very scanty, and hence to present any reliable pedigree is quite impossible.
Yes! My kind of biology text!
It saves the lengthy discussions for the good stuff, like this.
…only about 20-30 of the 34,000 species of spiders are dangerously poisonous to man (Schmidt, 1973; Maretic, 1975).
The prime example is certainly the black widow spider, Latrodectus mactans, from the family Theridiidae. The bite itself is not particularly painful and often is not even noticed (Maretic, 1983, 1987). The first real pain is felt after 10-60 minutes in the regions of the lymph nodes, from where it spreads to the muscles. Strong muscle cramps develop and the abdominal muscles become very rigid (this is an important diagnostic feature!).Another typical symptom is a contorted facial expression, called facies latrodectismi, which revers to a flushed, sweat-covered face, swollen eyelids, inflamed lips, and contracted masseter muscles. If the breathing muscles of the thorax become affected, this can eventually lead to death. Besides the strong muscle pain, black widow spider venom (BWSV) also elicits psychological symptoms, which range from anxiety feelings to actual fear of death. Apparently the toxin can pass the blood-brain barrier and directly attack the central nervous system.
Without any treatment the symptoms will last for about 5 days and a complete recovery may take weeks. About 50 years ago, lethality was 5% in the USA (Thorp and Woodson, 1945), but is now less than 1% (Zahl, 1971). The best treatment against a bite from a black widow is a combination of calcium gluconate and antivenin (e.g., Lyovac; McCrone and Netzloff, 1965) injected intraveously. Calcium causes the pain to subside quickly and the antidote binds to the toxin. The patient feels relieved within 10-20 minutes and will completely recover in a few hours.
The poison (BWVS) is a neurotoxin that affects the neuromuscular endplates, but also synapses in the CNS. The synaptic vesicles become completely depleted, causing a permanent blockage of the synapse (Clark et al., 1972; Griffiths and Smyth, 1973; Tzeng and Siekevitz, 1978; Wanke et al., 1986). One component of the poison (α-Latrotoxin) binds to a presynaptic receptor of cholinergic synapses (Meldolesi at al., 1986).
Neat-o! This is my kind of biology book, although you can tell from the dates of the references that it’s a bit old — there hasn’t been a death from a black widow bite since 1983, but I won’t mention that on any of the signage around my house.
I’ve been away this weekend. I walked back into the lab a short while ago, and here’s what I found.
A Parasteatoda egg sac had hatched out.
A second Parasteatoda egg sac hatched.
And another black widow produced a third egg sac.
Ooof. I know what I’m doing tomorrow.
It’s been quiet here on the blog over the weekend because Mary & I took off on a short road trip. Obviously the purpose of the whole drive was to find more crab spiders.
Also, the grass spiders have arrived! You can find their silk platforms in the morning, callecting dew.
See? That’s all it takes to draw me away for a few days.
Yay!
Soon enough, I’m going to be up to my ass in baby black widows.
We were strolling in the garden, and noticed that the place was full of horny pollinators. If they weren’t eating, they were fornicating.
It was like hanging out with teenagers. And I thought, if this was a 70s teen horror movie, what should I see next? And I was right.
If I were a spider, I’d want to just hang out in flowers and wait for those obnoxious teenagers to stop by. It’s the perfect place to find distracted prey.
Look what’s lurking in your flowers.
I got some crickets today, and it’s clear that that’s what black widows prefer to eat. Here’s the view one minute after tossing a cricket into their lair.
Yes, I have a skull in the container. For drama.
It was a quick death. The cricket bumbled about, bumping into the thicket of silk strands throughout the space, and the spider scuttled down, gave it one quick bite, and the battle was over. The spider is near the top center of the photo, with the motionless belly of the dead cricket below it, in the jungle of moss. It tried to hide, a futile effort given the tangle of silk everywhere and the potency of the venom.
I didn’t expect it, but wow, black widows are incredibly lazy. They find a corner and park their large butts there and don’t move at all, all day long. I know they wander about at night stringing silk all over the place, but otherwise, they’re like sulking teenagers who don’t wanna do nothin’ whenever you look at them. Boring!
Or are they?
I think maybe I haven’t been feeding them right. Yesterday, I caught a small grasshopper in our garden, and I tossed it into the black widow container. It bounced off a couple of strands of silk, and the effect was electric: the widow leapt out of her corner and stood poised in the center, suspended on its web, looking extraordinarily alert. She wasn’t looking directly at the hopper, but was delicately touching multiple lines — you could tell she was poised to sense any motion in her trap.
The moment was tense and dramatic.
The hopper moved. The widow instantly charged at it, tried to use her hind legs to tangle it up, and failed, so she retreated back to her central lookout. The hopper was terrified, and remained motionless for at least 5 minutes, while the spider was also motionless, but alert.
Finally, the hopper took a small step, and the widow surged forward and snared it with more silk. The hopper was kicking frantically, trying to leap away, but was hampered by the strong sticky silk, and every leap tangled it further in all that silk. So much silk. Finally, the black widow gave it one little kiss, and the hopper was almost instantly dead. Then she dragged her prey up to her calm quiet corner and ate.
I’ve been feeding her mealworms all this time. Maybe it’s not the spider that’s boring, but the food I’ve been giving her. The next feeding day is Tuesday, I think I’m going to have to buy a box of crickets.
