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  1. Saad Bhamla says:

    @MCKANSTRYPREP – What a beautiful video. The rapid contraction is remnant of certain kind of ciliates – I’ve previously seen this in Stentors and Vorticella – but the unique shape could be Spirostomum.

    Maybe @laks and @manup have a more educated guess.

    Good find though! :))


  2. Mckanstryprep says:

    Thanks I hope to hear back soon!


  3. laksiyer says:

    @MCKANSTRYPREP — This is a fantastic video. I agree this is likely to be a colonial rotifer and they are feeding. I could see a gut in some of them. If you still have the sample, perhaps you could zoom in to get a detailed view. Your video throws up an interesting thought that several colonial and unrelated organisms (such as colonial vorticella and rotifers) show a very similar aspect of stretching and rapid contraction. No telling what you will find in soil!!

  4. Mckanstryprep says:

    @ laks Wow! Thank You!
    It looked like they were feeding!

  5. James Pelletier says:

    I too wonder what are they doing, and how might the life of a rotifer be different in a colony versus alone? This paper entitled Rotifers: Exquisite Metazoans notes colony formation is not understood:


    I started to wonder about mechanisms of cooperative feeding.

    Then I saw the post by @Tom Hata https://microcosmos.foldscope.com/?p=9749 I am stunned by the slow motion video of a rotifer feeding on algae. It seems like the vortical flows generated by its coronal cilia pull algae towards its mouth, but then push algae away from its mouth – how tantalizing! If I were the rotifer: “Okay… Almost there… Yea! Noooooo! Okay try again!” Seems the bilateral symmetry of the flow relates to the bilateral symmetry of the rotifer, like each set of cilia pulls fluid in from the side (towards its mouth – yea!), but then out along the median line (away from its mouth – noooooo!).

    In a colony, I wonder if the vortical flows generated by adjacent rotifers could add together, so that fewer algae are pushed away and each rotifer catches more algae? Go team! Seems some research has been done on this, I need to read more.

    I am curious how much control the rotifer has over its cilia. Seems it can turn them on and off. I wonder if it can adjust the rate, or even adjust the rate of each side independently, like differential drive? They only have about 1000 cells total – how many neurons would they need for necessary sensors, controls, and actuators? Or if only it had a net along the median line, perhaps it could catch more algae?

    Also – I suppose I am making strong assumptions here catching more algae would be better for the rotifer, and the main function of the cilia is to catch food. Who knows – maybe they catch an optimal number of algae just as they are, or they use the cilia for various other functions, such as locomotion, as noted in Everything You Ever Wanted to Know about Rotifers, Part I:


    I am also amazed by the fast motion video of an anemone feeding on a rotifer – wow! Maybe colonial rotifers are too big to get eaten. Seems some research has been done on this, too.

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