Freshwater algae?

IMG_2109I recently examined a water sample from the reservoir at Pinnacles National Park in California.
I saw some cool  cells–I think they are filamentous algae? I am intrigued by the alternation of clear and green (chlorophyll containing) regions.

This post is part of Stanford BIO60


6 Comments Add yours

  1. laksiyer says:

    What a wonderful video. I wonder if those empty spaces are filled with some kind of gas for buoyancy. It appears that there are two kinds of algae,.

  2. Manu Prakash says:

    What a wonderful video @Mcyert.

    Another theory would be plasmolysis.. I saw septa in the empty cells. So could it be that some of the cells “retracted” into a smaller volume leaving behind an empty space filled with ambient fluid. Simple to test @Laks theory: do these guys float? Did you get enough sample that they are still alive.

    Beautiful video..


    1. mcyert says:

      This might be Oedegonium:

      “Two adjacent cells of a filament of Oedogonium are seen in which the cell contents, including chloroplasts, have contracted from the walls of the cell and are forming a globular mass in the centre of the cell which will become a zoospore.”
      see image at :

  3. Janice says:

    Hi Martha,

    If you would like to learn more about algae, take a look at an old reference book by G. W. Prescott, 1962, “Algae of the Western Great Lakes,” Wm. C. Brown Co., Dubuque, Iowa. It is available on the web through Although the taxonomy is out of date and the section on diatoms is wrong, it has lots of illustrations and information to get you started in the right direction. It’s the book that I and many others started off using many years ago.


  4. Manu Prakash says:

    @Janice: What a wonderful suggestion; I will get a copy since it’s freely available online.


  5. refract2art says:

    Respected Sir Manu Prakash
    I’m truly fascinated by your idea of foldscope, it got me goosebumps when i first watched your video in TED a few months ago, i was so intrigued by your idea that i build my own simple microscope from household items which could magnify fungus and other specimen in glass slides which brought at a local science store. I used a simple lens from webcam and my phone camera as a eye piece and set without using condenser ,i just adjusted the focal length such that it replaces the condenser. results were pretty good.

    Sir i am pursuing my masters in remote sensing technology and i am concern about the status of scientific knowledge and its importance in our country INDIA, I teach small kids in our local area school physics in every free time i get ,spending atleast 12hours a week, and exposing them to scientific world through the experiments and theories in their books.

    Every kid i know, also knows you and your invention and they consider you as a hero. A true science hero out of fiction books.
    So, i request you to meet them sometime when you visit INDIA and probably if you have free time. Children would love to see you.

    I would be thankfully if you could send us a foldscope that has changed lives of many. Children would be fascinated by seeing it.

    my email :

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