Our spiders are very quiet during the day, but we noticed that every morning their cages were full of fresh cobwebs. We knew they were sneaking around at night, and we resolved to catch them at it. A student, Ade Atolani, and I put together a gadget so we could watch.
We got a Raspberry Pi with a NoIR camera, drilled a hole in a plastic cage, and mounted it above a spider. I had no idea if this would work adequately at all — would we have enough resolution to even see the spider? How effective was this camera at seeing in the dark anyway? — so we just slapped together a quick trial run. We turned everything on late one afternoon, told the Raspberry Pi to take a picture every 60 seconds, and let’s see what we get. Miraculously, it all worked, first try.
What you’ll see in the video is a rectangular wooden frame in a cage, and we’re looking down on it. There’s a nice velvety dark cloth on the bottom, to minimize glare and reflections. At the beginning, there’s diffuse light from the window, so the infrared camera isn’t kicking in yet, but when it gets dark enough, the IR lamps automatically switch on, and the purplish black cloth looks pink. The important thing is that we can see the spider all night long, as it goes through bursts of activity. Awesome.
It looks like we’re going to have to sample at a higher rate, because the behavior is very bursty. We’ll enclose the whole set up in a light-proof box to get rid of the extraneous light. I also want to try some side illumination with an IR lamp to see if we can resolve the webbing as it goes up. This was just a pilot experiment, but it’s very promising.