“It would be cool to map the appearance of a pigment pattern,” I said. “Just photograph spider abdomens over development,” I said. “It’ll be easy,” I said. “Just do it!” I said.
So I took these Steatoda triangulosa embryos that emerged from their egg sac yesterday, and I sat down at my microscope and configured my camera to a useful and consistent setting (with a little tinkering, I found I could get decent photos at f/4, 1/80th of a second, ISO 3200 (!), at 64x on my Wild dissecting scope), lined up the containers with the spiderlings next to me, and thought I’d just march through and snap photos of the dorsal surface of the abdomen. Then I’d repeat this procedure every couple of days, and at the end of it all I’d have photographic series of pigmentation changes over time in a developing set of spiders. Simple! Except…reality intrudes.
First problem: spiderlings don’t sit still. They’ve got busy lives to lead, and because this is a longitudinal study, I can’t just kill them to make them stop movie (also, I’ve got this weird thing where I dislike killing animals). This is why I’ve got short exposures, too, because anything longer produces nothing but a blur.
Second problem: I’m trying to do three things at once, but I only have two arms. I’m moving the specimen container in the focal plane to follow the spiderling, I’m adjusting the focus to follow them in the vertical plane, and then I’ve got to click the shutter button at some point. That’s three. I’ve got a remote trigger, but it has to be aimed at a sensor on the camera, which meant it was kind of useless. I’m thinking of two possible solutions: a camera trigger I can activate with my mouth, or getting an additional limb grafted on. The latter is most appealing, former might be more practical.
Just to give you a taste, this is what a few seconds of my photo stream looks like when I’m done.
Third problem: That wide-open aperture means I get enough light, but the plane of focus is really narrow. What with all the running around, I’m really lucky if I get the plane of interest, which is the dorsal cuticle, in good focus. So I take lots of photos. It’s pure chance when I get the abdomen in the field of view, focused on the right surface. I’m going to have to compromise on the camera settings, I think.
Fourth problem: They’re only two days post-emergence, but they’re spiders! They’ve already filled their containers with crazy web lines running everywhere. When I’m lucky, they’re scurrying along the surface of their container, and I can sort of predict where they’ll be over a short period of time, but then suddenly they launch themselves upward, downward, at some cockamamie angle. Three dimensional travel over time is a pain. It also means they have no regard for your conventional orientations, so you may want to take a well-defined image from above looking down on their dorsal surface, but often these spiders are more comfortable upside down, or canted in some weird perspective. Those annoying photos above? Doubly annoying because that spider was constantly inverted, so you’re seeing the ventral side.
It was all far more difficult than I expected, but I should have known. This is how science always goes. You struggle endlessly to get stuff to work, you flail about tinkering and trying to develop the necessary skills, and then after you do it a hundred times, you might find it becomes routine and you can start gathering lots of data. You hope. And then sometimes you get preliminary data that tells you to rethink everything.
Like this.
In particular, look at the first abdomen at the top. This animal is just 2 days from leaving the egg sac, and you can already see the zig-zaggy S. triangulosa pattern in the abdomen, lightly. I’m too late to catch the emergence of the initial pigment pattern! I can still try to watch it progress and darken in the juvenile, but I’d really hoped to catch the pre-pattern gradually swimming into view.
That just means, though, that this is a different problem requiring a different protocol. I’m going to have to extract embryos from the egg sac earlier, and culture them in halocarbon oil while observing them on the microscope. The good news about that is that I’ll have to work on them before they’re capable of movement. Which is good, because I was ready to slap a spooder silly to stop them from scuttling about this morning.
I’ve got one acronym for you, poopyhead: TARDIS.
For your 3 hands issue, maybe you could invest in a sound activated trigger ?
Should not be too costly
Maybe hook a cable up to a wah-wah pedal (…grad student…whatever…) and trigger the shutter with your foot?
Would an LED gooseneck-type point light source work well enough to let you reduce your aperture?
PZ — Perhaps you could get them to sign a contract. Offer them residuals, a chance to meet other stars at the Academy Awards ceremony. Things that a spider with a burgeoning film career can appreciate.
Sound might be difficult if other people work in the lab. Closing a door might trigger a shot. Perhaps a foot controller?
A standard way of slowing subjects is to chill them. You might also find that they are rugged enough to drop a cover slip on them without damage. Maybe plastic cover slips are lighter, or a portion of a cover slip.
I’m calling it now. This is the start of PZ’s supervillain origin story.
https://images-na.ssl-images-amazon.com/images/I/81XAG9xFt4L.SX425.jpg
Can you collaborate with people who have fancy cameras made to capture objects in slow motion? I’d watch an episode of the Slo Mo Guys that showed spiders eating stuff or spinning webs in slow motion.
Hmm. Broken linky.
https://vignette.wikia.nocookie.net/villains/images/0/04/Octopus2HD.jpg/revision/latest?cb=20170803155054
@ Cinnamon #7
I’m with you on that. I saw this recently, and it was fascinating.
If you cooled them down would they slow down? (or would that introduce other problems). I remember this was the technique a guy who did the original Field Guide to NA Reptiles did with snakes, who just wouldn’t hold still (he was painting, if I remember correctly).
You want a foot pedal, not a mouth-activated switch.
Disclaimer: my brother is in the business of making and selling foot pedals as airturn.com
cool learning stuff already! so the pattern shows up far earlier than 2 days post hatching.
that’s what amazing about investigation you may have some idea where it will lead when you start out but you follow the evidence where ever it leads and learn stuff.
would just ordinary speed recorded video be good enough to extract still images with enough detail for the study? maybe HD video?
uncle frogy
The last one looks like an adorable little half-scrotum
I imagine you’ve already looked into it, but there has been a fair amount of research regarding the abdominal patterns on the Hawaiian happy-face spider Theridion grallator by Rosemary Gillespie.
It’s been quite a while since I’ve read any of it, and I’m going off of memory now, but I believe in the spiders she was studying, and some others I was looking into, their was sorta like defined blocks on the abdomen that would take different pigments, so that there was a set of possible color patterns. Also, I believe some of the pigments were byproducts of the spider’s diet/metabolism, so might not show until the spider has had sufficient feedings?
Anyways, I know a lot of people complain about your spider posts, and I really don’t like finding spiders near me, but I do think these are interesting.
I believe you have a bunch of those at your disposal. They’re called “students”. You say “Now!”; the student triggers the camera. You could offer extra credit as an incentive, if you were feeling generous.
You could even devise some sub-experiments to figure out which of them has the best reflexes.
Another option, besides cooling, is to anesthetize them with ether.
When John Lennon and Yoko Ono made ‘Fly’ they anesthetized flies with CO2 to slow them down enough to film.
What about a foot pedal trigger?
Can you do video and then just save one image from the video?
As knut7777 notes, CO2 is routinely used for Drosophila and other insect work, so a good chance it will work on spiders, too. A CO2 tank (with regulator), tubing, and a diffuser are needed. You can also test it out more cheaply with pellets that produce CO2 from Carolina Biological Supply.
Could you put them in a test tube and then be able to manipulate the tube to orient the spider?
Use a foot switch.
Many cameras have a 2.5mm jack socket for a remote control, in addition to the IR receiver. The simplest remote control is simply two switches, one connecting ring and sleeve to focus and measure exposure (same as a half-press on the shutter release), the other connecting tip and sleeve to release the shutter. My camera also releases the shutter with just the second switch — it just takes a little longer because it still does the autofocus and TTL flash metering. With manual focus and flash off, though, the shutter release is instant. So if your camera has a remote control port, all you need is a switch (like a foot pedal) and a cable with a 2.5mm jack at one end. Older phone headsets in the US have those jacks (e.g. a headset for a cordless phone, for a desk phone, or for a very old cell phone).
When they milk spiders for venom or for silk, they stun them with CO2, which paralyzes them without harming them. It wears off in a few minutes but it keeps them still for the milking. You might try that with the spiderlings.
#22 – Yes – a foot switch that smartly ‘clicks’ a circuit impulse. You don’t want a foot pedal, which doesn’t.
Like anot on said, ether or maybe acetone.
I used an acetone-soaked cotton ball in killing jar for my eighth grade insect collection. I put my first fifteen specimens in there until they stopped moving, then pinned them to styrofoam in a covered shirt box and set it aside. I lifted the cover the next day and to my horror they were all flapping, writhing and crawling in midair on their pins!
yeah, I guess it goes without saying that you don’t want to do anything that could fry your camera…
I guess you can’t knock them out briefly with something like ether or chloroform? That’s what they do with fruit flies when they want to count hairs, paint little advertising logos or the like. Gentle with the tweezers. Do your science. Then let them wake up at their leisure.
Maybe try a plenoptic (light field) camera, so it doesn’t frigging matter where the focal plane is? Lytro is no more, but if you can’t find any used merras for a decent price, apparently Raytrix is alive and well.
I can press my camera remote trigger with my incisors, but I felt that the button did not stick out enough to do that. So I modified it by using tape to wrap a bump-shaped rubber thingy onto the button. The button now effectively sticks out more, and the tape keeps my spit from getting to the electrics. Not a thing I tell many people.
If you are photographing pre-hatchlings, then its back to the microscope with ‘ya, in any case.
I hope I don’t come across as condescending, but does your university have a photography department? Could you ask them for help? I’m sure that it should be possible to mitigate a lot of these issues with your photography setup. Off the top of my head I’d be looking at:
Setting up a strobe or high-powered continuous light source so that you can open up your aperture (and drop your ISO), increasing depth of field and making the focus issue much more forgiving.
Using a camera that can do time-lapse. It takes a picture every second (or whatever you set it to) and you just focus on manipulating the container. You’ll end up with a lot of surplus, unusable images, but the good ones will be taken automatically, without you needing to trigger it.
Use a camera with good subject-tracking AF. You shouldn’t need to worry about focus if you have this combined with a wider depth of field.
When I was on the Rainbow Fish forum, some of the guys there used a little thin box made of clear acrylic, which was either put right in the tank or was in another nearby tank. The purpose was to photograph the fry. The rainbow fry could swim freely up and down but not really turn away from the camera. Some of those guys get amazing photographs that way. They did not have to worry about focus as they could do that ahead of time and just had to worry about tripping the shutter.
PZ
It seems to that you need a simple way to slow or freeze the spiderlings without injuring them. A gas, an electric field, other?
jack16
Many commentators suggest slowing down (to varying degrees) the spider. Others suggest various pieces of kit, such as pedals, switches, and students. The mildly deranged penguin points out an alternative is to speed up poopyhead. However, speeding up poopyhead would require some drastic revisions to rather fundamental laws of physics, so as long as that approach is on the table, she suggests other not quite normal spider–man physics.
One possibility is a pin-point modification of gravity to hold the spider in one place. Main problem here is that if not aimed properly, it might hold poopyhead in place.
Another possibility is to move the container about so the spider, to the outside observer such as poopyhead, remains in the same place. She suggests hyper-accelerating the evil cat, reasoning that an FTL cat would have great fun trying to get to the spider.
The obvious — and much simpler (she says) variant — is to hold poopyhead’s spacial position fixed, and move the rest of the Universe around so that, to poopyhead, the spider also stays fixed. The FTL evil cat can be employed to move the camera kit about so that, to poopyhead, it also seems to fixed in position, making it perhaps easier to use that if it was zooming about with the rest f the Universe.
Bendy light is another possibility, light which follows the spider whilst staying in focus. I point out the light is being reflected by the spider into the camera, not the other way around… she eats my cheese…!
Despite this cheese setback, it is clear altering physics provides possible solutions.