Diatoms!

This week I did more plankton trails with my home-brewed software.  It can be tricky to record the right video, as the bigger zooplankton like to swim into the frame and obliterate all the detail.  But I got a few good ones.

A small cladoceran generating a large current:

Also saw a few things I’ve never found before, like some super cute bosmina (relative of daphnia) from Okoboji, and a hydra from a pond in a field nearby.

Bosmina:

Hydra:

I later made cyanotypes on cloth of plants juxtaposed with the plankton trails.   Later in the week I attended some lectures on algae by Kalina Manoylov.  It was absolutely fascinating learning about dinoflagellates and diatoms.   I do wish I went to more algae lectures, these creatures are so interesting (their feeding mechanisms, my god!).

On thursday I went with the algae and aquatic ecology classes to Silver Lake Fen, to collect some samples.   I collected from the pools in the fen surface, as well as nearby silver lake.  When I got back I quickly took them back to my microscope… it took a little searching but I found them: diatoms!

I’ve never found diatoms before.  After attending Kalina’s lecture I knew what to look for.  And it helped using higher magnification and brightfield.

Diatoms have a glass exterior (frustrule) covered in pores that is amazing when examined via scanning electron microscopy:

There were tons of diatoms in the sample from silver lake.  Kalina helped me identify some.

diatom from Jess Holz on Vimeo.

As I understand it they move by secreting a mucus and sort of sliding on it.

^cymbella and dolichospermum
^cymbella next to melosira varians
^pinnularia
^gyrosigma (dead)

Also found some amoeba tests (shells they construct, which did not appear to be inhabited), probably euglypha:

Lastly, I made another zooplankton kaleidoscope.

plankton kaleidoscope from Jess Holz on Vimeo.