Some pond creatures, large and small

I collected some water from an artificial pond in the campus. Despite finding itself in the middle of an urban area, in springtime you can hear frogs calling all around. Now it’s winter and the pond is silent, full of rotting leaves fallen from the trees surrounding it.

I went there looking for a pond water sample to test my new foldscope. I walked all around the pond hoping to so see some sign of life, but there was nothing apparent. Maybe some algae growing in the middle of it, but out of my reach. I anyway scooped some debris from the bottom, in a random place and brought it home.

When I examined the glass jar against the light, to my surprise I noticed some little critter zipping around. The creature was too small to see its features by naked eye, but I also new that it would have been too big for the foldscope 140X lens. So I strapped the 10X lens of the LED module to my phone and took a video. I’m no expert, but to me this looks like a copepod!

But it wasn’t all, I noticed that one of the debris on the bottom, a pretty large one, was actually moving. Then it climbed the glass wall and I could see that this black blob was a worm, probably a flat worm. Here is another video of me trying to follow it around, I find it very fascinating how it seems to move around without any effort or contraction.

So after all there was quite some life in this random sample of an apparently dead pond.
I went to our local makerspace, where our DIYbio community regularly meets (www.biotop-heidelberg.de), to prepare some wet mounts. I put some water and spun down the debris with a centrifuge in the hope of collecting all microorganisms on the bottom. I removed the water from the tube, leaving the debris, which I loaded on the PVC well slide supplied with the Foldscope kit.

In winter there isn’t that much life around, but if you keep searching you will find something for sure. Here is what I think is an Urocentrum Turbo a little ciliate, that spins on its axis, you can also see that it has some kind of tail on the back, which it used to hold itself.

Not bad, but it was pretty small, I was hoping to see something larger… And after insisting a little more, my effort was prized and in the end I saw this: a bell animacule, probably Campanella or Vorticella. Another ciliate, much larger than Urocentrum and very fascinating to see. The cilia movement creates a vortex that pushes all the debris, and food, in the mouth (called cytostome). Ciliates apparently have their own preferences in terms of food, and in the video I took, you can see how a little green cell (probably an algae) gets caught in the vortex and ends up in the mouth. However, the bell animacule doesn’t like it and spits it out.

That’s it for the moment 🙂

I hope I gave you a nice overview of how many different sizes are there even in the microscopic world. The flatworm was 3 times larger than the copepod, which was 10 times larger than the bell animacule, which was 5 times larger than the urocentrum. I have also learned an important lesson: life is everywhere around us, even where you can’t see or hear anything. And the more microscopic it is, the more there is of it!

One Comment Add yours

  1. laksiyer says:

    Gorgeous, absolutely gorgeous videos. Love the details one can see in the vorticelloid. Thank you made my day. If you can put the flatworm under the foldcsope, might see something interesting in it.

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