MicrobeHunter.com Microscopy Forum

Does anybody know what this is?

I wish I had video. It is full of little dots (more than show up in the photo), and they are bouncing around quite rapidly. This makes me wonder whether it is a stage of an algal (diatom?) life cycle that is full of motile sperm.

It is a Desmid, most probably a Cosmarium sp.

Desmids are quite beautiful. Nice catch!

http://www.microscopy-uk.org.uk/mag/ind ... algdr.html

http://www.digicodes.info/Cosmarium_index.html

Hi Josh,
you mentioned the moving little dots. Difficult to judge because the foto does not show the details. However the algae may already be a bit damaged, since chlorophyl only partly fills the volume of the cell? So the moving dots may be bacteria that started to decompose the organic substrate? Just a guess..

Thanks, 75RR, fo the ID.

Regarding the moving dots, bacteria seem like a good possibility, but I don't know that the chlorophyll pattern indicates damage. Aside from the fact that it is symmetric, it appears that some Cosmarium sp. are like that, such as this one:

http://www.digicodes.info/Cosmarium_gon ... gidum.html

The Wikipedia article on Desmids (https://en.wikipedia.org/wiki/Desmidiales) mentions "characteristic crystals of barium sulphate at either end of the cell[9] which exhibit a continuous Brownian type motion". Might this species have something like that not restricted to the ends of the cell? I could believe that the motion I saw was Brownian motion.

Jam's Germs: Brownian Motion in Desmid

https://www.youtube.com/watch?v=o9B5JnLymNE

75RR wrote:Jam's Germs: Brownian Motion in Desmid

https://www.youtube.com/watch?v=o9B5JnLymNE

Thanks!

I had more dots than are visible there, and they were smaller (or the cell was larger), but I'm fairly sure that they were the same thing.