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


5 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 It is available on the web through Although the taxonomy is out of date and the section on diatoms is wrong, it has lots of illustrations and information to get you started in the right direction.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.


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