Life in a liter of Pond water — Euplotes– Day 1

In the little town I grew up in India, one of my favorite pastimes was pond watching. A little depression near our school would fill up during the monsoons, and life would spring out as though spontaneously. We (friends and I) would count whatever we could see and marvel at the great struggle (or dance, depending on your view) of life. The ecosystems would change from time to time and then there would be a whole new community of inhabitants, providing endless entertainment. Many decades later, when I had access to a compound microscope, I realized I could “bring the pond home” and enjoy the dance of life under a lens. Now with a foldscope and with winter rearing its ugly head early in the year in the North earth of US, and the floral landscape all but gone, I am planning on bringing the pond home with am aim to identify as many life forms as possible (Another table perhaps).

Near my residence there is this aptly named Inspiration lake besides which there is an un-named pond. A nice green sheen of duckweed had grown on it recently and since I hadn’t foldscoped the duckweed, I took a liter or so of the pond water with a few duckweed in an old spice bottle and have kept the open bottle out in the balcony. My goal is to identify as many species as I possibly can, and with a lot of help from friends and foldscopers, for as long as I can. I will try to keep it systematic and where possible record physical parameters.pondinabottle

For all these observation, I am using a cavity slide. I take a drop of water, put it on a coverslip, add vaseline to the sides, invert the cavity slide over the coverslip such that the drop is in the cavity and invert again (Will put up pics soon). Sometimes the drop hangs (and hence this is called the hanging drop), at other times, it fills up the cavity, which is fine too. This way the foldscope doesnt get wet in my hands. You can make your own cavity slide too, and I think I have seen @Manu and @Matt do that.

Day 1 began with a bang with a plant, a ciliate, a flagellate, an animal and a bacterium. The pH of the water sample was ~6

1, Plant: Lemna (duckweed). Taxonomy: Plantae->…Monocot ->Araceae -> Lemnoideae. This is actually a flowering plant related to the jack in the pulpit and makes a tiny flower, although this far I haven’t seen the flower under the foldscope. It also reproduces asexually by budding and I caught one such in the middle of the process. I am hoping the lemmas flower someday.

2. The Ciliate: Euplotes. Taxonomy. Alveolate->Ciliophora->Spirotrichae The star of the day, what a character. Whenever I see a ciliate like Euplotes it reminds me of the morphological and functional landscape that a single cell can explore. When on a solid surface, euplotes literally walks with its cilia. These cilia are actually fused to form conical structures called cirri. At other times they swim very efficiently. You can see ciliary motion in its prominent oral apparatus and at times you can see the waves of water current. As compared to this one-man-show, are the multicellular life forms with different cells for different functions. In the video below, you will see a single-celled euplotes (~100 microns) next to a multicellular rotifer (~200-250 microns) to get an idea of scale. I have observed single cell ciliates consume multicellular rotifers! Also note the euplotes with intracellular particles (a full meal?) and an occasional contractile vacuole. Excerpts follow:

3. Rotifer. Metazoa->Protostomes–> Lophotrochozoans—> Currently phylogenetics places them in the Lophotrochozoans  along withe annelids and molluscs, but phylogenetics is a data-dependent field and these relationships might change with more data. Also known as the wheeled-animalcule. Busily grazing on the duckweed frond. About 200-250 microns in size. You can see that the foot is used to anchor to substrates by the toe. A clear eye spot is visible as also the stomach and corona.

4. Flagellate. Dont know this genus, but it has a tumbling way about it.

5. Bacterium. Perhaps Nostoc (Bacteria->Cyanobacteria). A cyanobacterium that divides by breaking off. I counted ~40 bacteria in one chain and each is about 10 microns long– Pretty large for a bacterium.


More to come in the future.

6 Comments Add yours

  1. Saad Bhamla says:

    @laks: Incredible post!!

    The ciliates video is a david meet goliath image. You captured it beautifully : )
    It is very interesting how the rotifer anchors itself – its beautifully leveraging its body around the leg.

    What is also striking is their transparent bodies, with just the dark eye-spots. I can only imagine they look spectacular under dark-field!


  2. laksiyer says:

    Yes @Saad, Dark field would be perfect for these and I cant wait.

    @Manu @Saad, @Jim @Tom I have been thinking about this for long, but perhaps it might be better to think aloud. Why are we so constrained by the sample volume of the slide? Can we not have say a flat thin transparent polythene tube where the sample can flow continuously and then we stop where we want to when we come to a good view?

    A thin polythene tube neatly fitting into the foldscope slots, gravity for the flow and clips for constraining, is all I can conceive. I know you guys can come up with something really smart.

  3. Matt.Rossi says:

    @Laksiyer I love the idea of the polythene tube, as well, for viewing liquid samples in the foldscope. I’ve had good luck viewing larger critters using well slides (though you never see the many videos in which I accidentally pick them up with my lens), but smaller creatures, I have a hard time focusing on.

    Your shots of these microbes are incredible, Laks…something to work toward.

  4. Manu Prakash says:

    Oh my – @Laks: what an incredible jungle – you captured the beauty of this so well. I will say a lot more about things I found in the video; but a comment about liquid samples first.

    Fantastic idea to use a tubing for continuous explorations of the ecosystem. That way – it all lives in the landscape as well and is confined on one axis too. One could also use a flat tip pipette with reservoir on one end and slide on the other – all in one single piece.

    Finally, many months ago; I had made a infinite field of view slide where I wanted not to be constrained by the size of the slide. The idea worked; by coupling light source and lens magnetically – since everything is so small. I just realized; the current focus locking scope also uses a similar magnetic coupling – I will upload the photos for the same. What this would do us exactly what you said but in both X and Y dimensions.

    Also, for really big things that live in water; I often use zip lock bags and just insert the corner of the bag in the microscope; keeping the animal both confined and bathed in water. This has worked very well for me. Conference batch cover does the same.


  5. laksiyer says:

    @Manu the infinite field of view sounds like looking at stars!! We can now do a perfect equivalent of the Kepler project where a camera just captures moving microflora and then we can either crowd source the identification or do it oneself. I am going to use the ziplock bag and yes the badge covers too, great ideas.

  6. Manu Prakash says:

    @laks: I will upload some pictures of how to configure the “infinite field of view scanning” using the second pair of magnets in the packet. The analogy with the night sky is apt 🙂


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