Day 31: A colonial vorticella: First explorations with fixed focus and dark field

Day 31: 11. Vorticella (Alveolate->Ciliophora->Oligohymenophorea->Peritrichia->->->Vorticella)

Ever since the first days of collecting the pond water sample (Day 1), I have been observing this feathery object floating around. I always thought it was a  feather fragment until today when I saw the object moving upwards and then in other directions almost with intention. I put it on a watch glass and looked at it under a low power microscope (40x). It was a pretty striking Vorticella colony. Here is a view at low power (40x) view. I wonder if you have read this wonderful post by Manu on the speed of the Vorticella spasmonemes.

Left. Vorticella at 40x. Right. The same on a watchglass.

As you can see the Vorticellae are all connected like leaves to branches in a tree. The stalk is like the tree trunk and each Vorticella beats its cilia and the net movement is the result of the propeller-like action of all these vorticellae–Like a flying object with many propellers. Wonder if there is a signaling system between members of this colony (there has got to be one), that decides where to move. Normally we are taught that Vorticella have a motile phase where individuals move around and a sessile phase where they cluster together are are fixed. But here is an example of sessile Vorticella that move around as a group. I even took a movie of the same at low power. Manu, we need a 40x lens on the foldscope some day 🙂

However the most exciting thing was to use the newly rigged foldscope with dark field and fixed focus. This takes the cake (Thank you so much Foldscope team).

First foldscoping without all the new additions with my normal setup. This time I put a tape over the LED light source causing the light source to be more uniform. I really like the view.

Now Foldscoping with fixed focus and dark field. The dark field needs some adjusting, but be assured in due course this will mature. You can see the beating patterns of the cilia more clearly in this. I filled up my phone with videos, so here are some excerpts  (apologies for length, but I couldn’t contain myself). Fixed focus allows you to take movies or snapshots for as long as you want.

As you can see the Vorticella colony had broken up being squeezed by a water bubble in my slide(not shown) into the individuals (telotrochs?). I am still trying to figure out the optimal way of making slides for the foldscope with liquid samples. The most optimal one is that which can take a sizeable volume and not leak from the sides of the coverslip. Am going to try playing with coverslips separated by broken coverslips glass pieces. Also, a coverslip that can cover the whole slide would be more entertaining— working on all these.

Previous posts with this pond water sample: Day 1, Day 6, Day 17, Day 27

11 Comments Add yours

  1. Manu Prakash says:

    @Laks: Beautiful post. I have seen many vorticella colonies attached in this branchibg pattern (mostly on other substrates – never just by themselves).. So that’s a really novel observation; in the end – if the colony is large enough; why not just attach to your own clonal type.

    That brings me to point number 2; which you hinted In your post. Vorticella generate large vale feeding current (compared to the size of the organism; roughly 5-10 body lengths). But when structured in this pattern; the flow fields are all coupled. I wonder if a branchibg pattern can enhance to bring even more food as compared to just the addition of the flow field. That would be an incredible example of 1+1 > 2 – of you see what I mean.

    I will try to do a flow field measurement for a colony and report back. I have consistently found vorticella on dead insect debri; but don’t know how to look for one which is a colony by itself.

    Glad you have a DarkField working. Now to point number 3; what are they ejecting from the inside. It looked like organelles at first glance. Too large to be a waste vesicles; but they probably eat big algae as well.


    1. laksiyer says:

      @Manu. Now that I know how they look, these can be spotted in pond water bottles like a whiff moving about purposefully. They are pretty delicate though. I should have captured their macroscopic movement in the bottle. I am sure I will find one soon. I like the idea of when 1+1>2 and also the idea that more food can come in and perhaps this is why they are clonal. flow field measurement sounds exciting.

  2. Manu says:

    @laks: I have been looking for something small (5 microns) that is not too dense compared to water and is found in the kitchen – as a tracer for fluid flow. This is how I did the “Atta” post actually; since I wanted to find a flow tracer. Keep your eyes open for a particle like that; I am thinking of coffee, ink particles, paint etc etc.. needs to be something non-toxic, 5 microns and available in every home 🙂

    I am already imagining how beautiful the collective flow field is going to look like. Can’t wait.


  3. laksiyer says:

    Hmm. will test a few items and see. It would be great to see the flow field.

  4. Marie Herring says:

    Maybe you’ve already tried this, and it’s not exactly a household item, but rice starch is in the right size regime (3-8 microns). There’s waxy rice starch as well, though that might not wet out appropriately.

  5. Manu says:

    @Marie: How do I get waxy starch? Is this a food item?

  6. Paul Joseph says:

    @laks, how did you fix the focus on your foldscope ?

  7. laksiyer says:

    There are two ways to do it.

    1. Up unti now, after affixing the foldscope to the phone, one uses a stack of papers (I used to use these glossy advertisement cards, a pack of nice cards would do too) to lift up the foldscope till the focus is fixed. The phone is attached on one end using tape and is on a higher surface. With this you can achieve a really decent focus.

    2. More recently, the Foldscope team has just released a new feature by which the top flap which holds the slide is lifted using a paper wedge. Manu tells me that this is can also be done with the v1 foldscopes with some modifications. Like an upgrade. I am sure you will hear from him soon on this.

  8. Manu Prakash says:

    @Paul: Yes; we will soon be announcing an “upgrade” you can install in v1 Foldscope. Also; phase two (which will be significantly bigger) will already include focus locking. It’s a feature we have been working for a long while; just ironing out some wrinkles.

    To give you a clear picture of what @Laks just described above: read my post here:

    Using this, a foldscope user imaged “brownian motion” – which is a very cool post.


  9. Paul Joseph says:

    Thanks for sharing @Laks !

  10. Paul Joseph says:

    @manu, What is a pending comment? You replied to my earlier query on the focus locking foldscope but it shows up under my “pending” comments and I am unable to reply to it.

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