Maya’s experiment

I was not looking forward to today — we have these swarms of spiders hatching out, and we have to do something with them all. They’re in cramped little petri dishes, an entire clutch together, which is fine early on, since they naturally aggregate after first emerging from the egg sac, and then a few days later start ballooning and dispersing by wafting away on the wind. “Wafting away on the wind” isn’t a great strategy for maintaining a laboratory colony, though. Last year I would pluck them out one by one and put them in tiny individual containers, which is ridiculously labor intensive, and then feed them flies individually, even worse, and that wasn’t going to work at all with the numbers we’re dealing with. Especially since fall term starts way too soon, and students are going to be occupied with mere classes.

So my student Maya is doing a simple experiment to see the effects of population density on juvenile mortality. We didn’t put the spiderlings in individual containers, but in two different sizes of containers in different numbers. We opened up the petri dishes of spiderlings and counted out individuals into larger containers.

It was amusing and different. The spiders, as soon as the lid was off, saw freedom awaiting them and would put out a thread to start ballooning. We’d gently sweep in with a paintbrush and snag them, move the brush over their new container, and give a little shake — sometimes they’d oblige by neatly rappelling down, sometimes they’d jump off, sometimes they’d get obstinate and you’d have to dab the brush against the container to convince them to move. Meanwhile, while you were distracted, more spiderlings were launching themselves skyward. More than a few escaped. More than a few, I’m sure, snugged themselves down in our clothing. It’s all good.

(Oops, just found one in my shirt sleeve. Now my office has some new residents.)

The end result is that we now have a known number of spiders in known volumes of space. We’ll track survival every few days to see how they fare. Once they get larger, we’ll spread them out a little more, but currently we find that the adults coexist nicely with two in a 5.7L container, so we’re hoping that the babies won’t fight and cannibalize each other at a somewhat higher density.

(Just found another baby under my shirt collar.)


  1. Rich Woods says

    A spider took up residence in one of the lower corners of my bathroom windowsill four or five weeks ago. It was tiny at first, barely 2mm long (excluding legs). It span a horizontal net about 12cm by 4cm with several dozen support strands and some traplines between them, in all about 15cm high. Within a few days some aphid corpses appeared on the net (I’m usually able to keep the top window open for about five months over the summer) and the drained husks later fell (or were moved off the net) to the windowsill. There are about 20 insect corpses now, and I think the spider has moulted twice (it hides right down in the corner for a day or so). It’s now about 4mm long and I don’t need to fetch my glasses to be able to see its legs.

    Yesterday morning the nighttime temperature was a lot colder here than it has been of late, so when I had a shower the vapour condensed on the webbing for the first time. The supports and traplines now extend about 45cm up the window frame! This tiny little creature has built a trap structure with a volume of maybe eight litres. No wonder it’s doing so well at keeping the greenfly out of my house.

  2. jrkrideau says

    Visiting PZ’s office could be interesting for the arachnophobes.

    Dr. Myers is holding a job interview. Screams of terror and the candidate is seen charging out of the building and trying to get a flight to Saudi Arabia.

  3. Pierce R. Butler says

    “The Literature™” has no manuals of applied arachnidoculture?

    (Apologies for yet another Greek-Latin mashup…)

  4. bcwebb says

    This article:

    says that spiders will avoid ballooning takeoff if the windspeed is too high (>3m/s ~ 6mph.) I wonder if you could put a fan in the enclosure and see if you can scare them into staying put. I’m curious how long the inhibition continues – maybe a good burst of breeze could get them to stay put even after you turn off the fan and want to open the lid. The article explores excitation of ballooning but not inhibition by higher winds.

    I suppose another route would be to chill them a bit.

    Can you smoke them like bees?

    So many possible experiments…

  5. Pierce R. Butler says

    bcwebb @ # 4: Can you smoke them like bees?

    Yeah man, but you just don’t get the same buzz…

  6. Wrath Panda says

    My first thought was that you should also manufacture tiny little gladatorial weapons for them. Make the experiment more interesting (and potentially lucrative from ticket sales!)

    My second thought is that the prof is clearly running some kind of survival of the fittest programme. He’s going to train the survivors of this “experiment” to be the vanguard of his occupation force and will mutate them using Science in to 8 foot tall killing machines.

  7. GerrardOfTitanServer - formerly EnlightenmentLiberal says

    Friendly reminder that many leading climate scientists like James Hansen, Kerry Emanuel, and others say that it’s the Greens, not the climate change deniers, who are the biggest stumbling block to fixing climate change, because of their opposition to nuclear power. James Hansen in particular notes that fossil fuels, especially natural gas, are a major funder of Green orgs because they’re useful for attacking the only real competition, nuclear.

  8. GerrardOfTitanServer - formerly EnlightenmentLiberal says

    Crap. How did I get the wrong thread? I even read mangy of the comments and everything