Strange Microorganisms in Algae Sample

Noticing the algae covering the sides of the water feeder for our horse, I decided to take a sample and see if I could spot any microorganisms under the foldscope. As it turned out, I was in luck!
I first noticed the creature on the right because of the strange mouth-like appendage at its centre, that looked as if to be biting something, though I’m not sure what. I then thought that the motion reminded me of a heartbeat, though I knew this couldn’t be the case, as the pulses later grew intermittent, and creatures of this size don’t have circulatory systems (at least, to my knowledge, not in the form of those seen in larger organisms).

Zoom out from the most active organism. Notice the second one in the top left as

At first I thought I’d caught a smaller microorganism in a bubble due to my not pressing the PVC coverslip down properly, but I now believe that the bubble is indeed the cell, with the ‘mouth’ located near the centre. I am reaffirmed in this belief by the fact that the less active organism in the top left has a similar shape to this one, and both have a slighly yellow-orange colour to them that differs to the background.

Notice the movements towards the bottom of the cell, as well as the other organism jerking in the upper left hand corner towards the end.
I attempted to place the foldscope in dark field mode to see if I could spot anything new. While the ‘mouth’ is less-defined, notice the ripples that can be seen as it opens and closes.

Any help to identify what these microorganisms are would be greatly appreciated!

Edit: Below are pictures of the trough that I took my sample from

6 Comments Add yours

  1. laksiyer says:

    Nice catch. These are bdelloid rotifers that are resting. The beating organ is the mastax of the pharynx (like a grinder).

    1. Tigercat says:

      Thank you! I’ve just been reading up on them, and they’re quite fascinating. Apparently, a batch was sent up to the ISS last month.

  2. Manu Prakash says:

    You have indeed caught two remarkable creatures – very clearly of the same kind. It’s beautiful to watch.

    Few ideas; one possibility of a beating “heart” like organelle in single cells is a “contractile vacuole” that pumps things out of the cell. From the contrast and the location, I believe that is less likely – but still a possibility.

    My intuition from the shape and activity is that you have some Rotifers species at hand. I know we have few rotifer experts in our community – so I am curious what Laks and @Yash might think.

    Just a beautiful capture. Could you please also attach a picture of the environment/surrounding – that made you think about taking a sample.

    Beautiful detective work is ahead of us all. Thanks for sharing and exploring!


    1. Tigercat says:

      I have updated the post to include pictures of the environment from which I took my sample

  3. Manu Prakash says:

    @laks: you beat me to my comment by 1 min – in which I said; I bet Laks knows what species of rotifer it is 🙂

    This is why I love this community so much!


  4. Thanks for the mention @Manu, I appreciate that.

    What an interesting find…
    I’m skeptical of the organism in question. There was an earlier post on this site that baffled me.
    It had to do with a Rotifer looking like a Gastrotrich. Here’s the link.

    I did some digging today and I found this abstract of an article that blew me away. Here’s the quote,

    “Rotifers and Gastrotrichs show many morphological and biological affinities which allowed the inclusion of both taxa into the Aschelminthes as two classes. However, the same affinities are currently considered to be the result of convergent adaptations consequent to a similar meiobenthic or planktonic lifestyle, and therefore they play a different role in recent phylogenetic views on their position. Ultrastructural and molecular characters separate rotifers from gastrotrichs as two clades resulting from different evolutionary histories.”

    Here’s the link,

    I’m much more curious than you are now. Science never stops enthusing me on a daily basis.


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