Foldscoop 1:3. Long-term Lichen suspensions

Laziness is a good thing; sometimes. Previously I had posted on observing tardigrades, ciliates and nematodes (1, 2)  in Lichens. It so happened that due to a hundred obstacles that life so often places, I  forgot to observe the lichens suspended in mineral water for about two weeks. By this point, the water turned dark brown and wondering if something had grown, I peeked into three such samples that I had set aside. To my utter delight the samples were buzzing with life. Two of them (from independent lichens) were filled with the comma shaped ciliate that I had noticed previously (Ciliate-19782-7-LI) and one had an abundance of rotifers.

  1. In the video below is the star of the post, the comma shaped ciliate that I realize is a member of the Colpoda genus of ciliates. Look at the videos for more details. I suspect this is related to the ciliate that @MaxCoyle saw some time back. There is another ciliate too that I call Ciliate-19984-1-LI in the video.

2. Also found along with these was a Tetrahymena-like ciliate (Ciliate-19984-2-LI).

It was also time to call the DC micronauts to join the fun and it was a riot.  Each one got their own lichens suspended in water to look for tardigrades and nematodes, and they also had the option to study the explosion of ciliates and rotifers from my samples.

3. Here is a video by DC micronaut Vaish on the sample with many rotifers.

4. It was an intense session with the kids, and we had a lot of fun.

img_1676

5. Now my laziness knew no bounds as I left the same sample on my table until now (it has been some 6 weeks). The following video is of the sample which had an explosion of Bdelloid rotifers (Rotifer-19984-5-LI) and still is filled with them and the other two ciliates too. However the reason why I am able to get such long-term cultures is seen at the end of the video.

Perhaps after about a couple of weeks, a lot of bacteria start growing in the culture. This is a substrate for ciliates and rotifers to grow. In due course these multi-organism systems reach an equilibrium.  These can be modeled by  Lotka-Volterra models. For example, here is a simple two-species predator-prey model. With more than two species you can get oscillations, chaos and various equilibrium states. Will post those explorations someday, but here the resources might be determined by the number of bacteria and a simple competition model between the larger eukaryotic species for the resources (bacteria).

BTW, I have successfully sub-cultured Colpoda, but that is for another day. I hope you had a chance to contribute to the exciting foldscope kickstarter campaign to put a microscope in every child’s hand.

 

 

4 Comments Add yours

  1. Manu Prakash says:

    @Laks: What an incredible series of species – all from a single lichen. That’s remarkable in it’s own right. That really changes my view point of how many of these ciliates are being transported around.

    Now; to be sure – what if you had made a lichen suspension and allowed oxygen diffusion from air but not of spores that might be in the air. I just want to rule out floating spores. This is a general question I am thinking about. Maybe it’s time to make a “swan’s flask” (https://en.wikipedia.org/wiki/Swan_neck_flask) and rule out spores floating in the air.

    Incredible diversity – I think I have never seen a Colpoda. Love the “comma” shape and the diversity of swimming motility. The bacterial suspension is such a treat. love seeing them being gobbled up by the rotifer.

    I will replicate your lichen culture – and see what;s happening. I wonder if I can already find ciliates in “moist” lichens. That;s an incredible place I have not looked. and with so many micro-envioronments – a fantastic place for speciation to occur..

    cheers
    manu

  2. laksiyer says:

    @Manu: I’ve been grappling with that quite a bit. What if these are random associations due to floating spores. For example, Colpoda seem to go into a dormant state once the resources are used up and form tons of little spherical cysts (that I am planning to regenerate). These cysts could easily be floating around. I do use a little plastic petridish that is covered to prevent contamination (a swan-neck equivalent??) , and water that is generally free from too many contaminants, but I simply cannot rule out that these can come from elsewhere, such as the bark of the tree or floating spores, during sampling. The only way I can be sure these are real associations is repeated sampling of lichens either from the same tree or from different trees and finding the same species. I have recovered Colpoda and this rotifer twice. independently Have been sampling several lichens repeatedly after that.

    The cool thing is that I am seeing ciliates I dont normally see in my little pond. I am also trying to use this as an opportunity to grow ciliates consistently at home which will make them amenable to experiments and staining. In my next post, I shall talk about larger ciliates that I isolated from another such culture. One thing that gives me some hope are reports that Colpoda are often recovered from lichens. http://www.balticforestry.mi.lt/bf/PDF_Articles/2012-18%5B2%5D/Satkauskiene_2012%2018(2)_255_262.pdf

    Curious to see what you will get in your lichen suspensions.

  3. Manu Prakash says:

    That’s absolutely wonderful @Laks. I am really excited about sampling Lichens now – since it’s been raining quiet often now; I will also try to find droplets in lichen and image directly. Maybe they are “thick” with ciliates.

    cheers
    manu

Leave a Reply