Artist Lab Report:
diatoms!
by Jess Holz

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.

“Artists and scientists are both asking questions about the world, they’re just doing it in different ways”
Alex Braidwood
Director, Iowa Lakeside Lab Artists-in-Residence Program

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