Polarized Explorations Part 3!! Copepods and Ciliates

Hello everyone!

Thanks to iGEM I’ve had absolutely no time for foldscoping lately ๐Ÿ™ but I’m determined to exploit this mini vacation in Ratngiri to its fullest ๐Ÿ˜€

Till now I’ve observed some pure chemicals and fruits in cross polars but this time I’ve tried doing something that I’ve been dying to try my hands on andย  that is imaging live samples in polarization!

While observing this water sample I remembered that When I observed recrystallization through crosspolars I noticed thatย  compounds in melted form do not show birefringence..only the crystal forms do…That’s when I started to wonder, would ciliates show birefringence at all?

Even if they do posses any optically active compounds in them they wouldnt be in crystal form…I had no hopes from ciliates

Location from where I collected the water…Can you spot the shoal of fishes in there?
And the cute turtle? There were 2 such turtles in there ๐Ÿ˜€ sadly one went inside the pond while I tried to click.

So here are our ciliates!

I thought if not ciliates let’s see wether atleast the Pediastrum shows birefringence and Voila!!

What I observed was just the opposite of what I expected!! A ciliate showing birefringence!! How??? Did it engulf particles of mud that showed birefringence?? What could the reason be??

Here are some pictures of the beautiful Pediastrums

The next thing in the sample that caught my attention were copepods!

Copepods are planktons found ubiquitously in fresh and sea water. They have a mineralized chitin containing exoskeleton. Would that account for some action in cross polars?The thought of a copepod showing birefringence excited me !!

I thought, let’s try and see!!

And then began the chase…

Copepods swim irritatingly fast!! I spent hours trying to catch them with my tiny dropper and finally got hold of these devils

So here is our beautiful copepod with 2 egg sacs

And here it is!!! In cross polars!!


Beautiful! Aren’t they? I have seen copepods numerous times but never thought they’d look this glorious just by playing around with some light!!

Hope you all enjoy the findings!

Oh and here’s the moon rise in Ratnagiri ๐Ÿ˜€

Have fun foldscoping~

Mitali Patil

Third Year Undergrad,

Ramnarain Ruia Autonomous College.

9 Comments Add yours

  1. laksiyer says:

    @Mitali. This is one of the most startling posts of recent times. Your focusing abilities are only next to the best like @Manu. The clarity of the video is superb.

    Refractile bodies in ciliates under cross-polars just made my day. These could be one of many things that have been reported previously or perhaps something entirely new. In some cases they were shown to be little bacteria in a vacuole (kappa particle of Paramecium),, in others they are high concentrations of proteins, or crystallized salts such as purines, or perhaps polyphosphates. Exciting stuff.

  2. Mitali says:

    Thankyou Lakshmi sir ๐Ÿ˜€

  3. Cristina says:

    @Mitali: this post is absolutely fantastic! I now have a polarized film and will try to discover new things using it. Loved reading your words and feeling the enthusiasm they transmit.

    1. Mitali says:

      Looking forward to more polarized explorations!

  4. Manu Prakash says:

    Incredible work @Mitali. I will stop buying Christmas lights from now onwards – just absolutely stunning. Reminds us all; just to trust our intuition and try our experiments – without a bias. You just proved this so wonderfully.

    Now; the origins of bi-rifringence in ciliates vs. copepods might be entirely different mechanism. Several ciliates do show bi-rifrence – but what is it from? Let’s dig more on this. Also; I have been thinking; we could use them as a reporter (kind of a sensor) of the internal cytoplasmic state of the ciliate. If it is a crystalline material; it will be very specifically;y dependent on the chemical environment.

    Now, for the copepod – from the image – it appears that different muscles groups are showing up in different colors. Muscles have a remarkable hierarchal architectures; so it’s not totally crazy to think it will interact with light in different planes differently. we should check if muscles show bi-rifrengence. And if they do; can we use this as a reporter for muscle state (fatigue for example). That would be remarkable – if you could see if an animal is tiered ๐Ÿ˜‰

    I am always amazed by your work Mitali. You inspire all of us.. keep exploring.. and I can not wait for another Foldscope gathering soon. I am working on making that happen soon.


    1. Mitali says:

      Thankyou for the encouraging comments Manu sir! ๐Ÿ˜„
      The idea of using birefringence as a reporter is so damn cool! I just observed an arthropod in cross polars and the leg muscles do show birefringence.Infact there were 3 bundles of muscles in the same leg showing different colours (thats how I concluded that there are 3)! And they’re not visible in Bright Field. More on this in the next post ๐Ÿ˜„

      1. Manu Prakash says:

        That is fantastic!! Indeed, birefringence in a biological material arises from ordered molecules.. and muscles being made of arranged sarcomere units – would show something like that. Since they are all oriented differently, you should see different colors. And because of this, you could possibly count and lay out the exact arrangement of all the muscles in these tiny creatures. Itโ€™s brilliant – what an incredible idea. Canโ€™t wait to read your next post.. maybe you can compare different copepod species and see if you can find common patterns in muscle architectures.

        I canโ€™t emphasize how happy it makes me to read your posts Mitali. You have a brilliant mind. Keep exploring..


  5. Tulasi Mastanamma says:

    Really amazing work. The concept, clarity of videos and i am sure you are an inspiration for us to follow.

    1. Mitali says:

      Thankyou ma’am!

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