A Diatom? Not Sure - ID Help Request

Mitch640 · Post by **Mitch640** » Sun Mar 27, 2011 4:49 pm

I filled two 1.5ml centrifuge tubes with almost clear water collected at the river the other day. Let it spin for 5 minutes, not really knowing what to expect. But I got a nice dark pellet at the bottom and it turned out to be a lot of diatoms and jelly stuff.

I found this thing first. Looks like a micro turtle shell.

Then, further into the drop of water, I found one I thought was a mini turtle alive in the shell. The reason I thought they were diatoms is, they moved slow, like diatoms.

Another shot of the above one.

And then, a second live turtle. This one was messing with the round thing, pushing it around and generally pestering it.

Another shot.

BJ · Post by BJ » Wed Mar 30, 2011 9:16 am

hi Mitch,

I am not confident about either of these identifications - both could be way off...but here goes.

I think that your first "turtle" might be a detached calcium carbonate incrusted oogonium of a charophyte algae such as Nitella. The shell should be spirally patterned, but this might not be obvious if the focus is across the middle of the structure.

Second turtle might be a diatom in the genus Surirella, perhaps Surirella capronii. This is a motile diatom with lobed golden brown chloroplasts like your specimen. .... but again I would like to see another plane of focus to see any detail in the frustule.

In both cases some indication of size would help narrow the field.

I really could be way off beam with these identifications !!

You are finding some interesting material - thanks for sharing.

boa sorte
Brian

Mitch640 · Post by **Mitch640** » Wed Mar 30, 2011 12:01 pm

Brian, thanks for looking.

I can see now that the empty turtle shell can't be one of the same species as the live ones. Although, it was on the same order of size.

Here are two more shots, one with a size overlay on it. They are of the same bug, the second one is just seconds later and had turned. I can't see them when shooting with flash, so I did not see it turn or whatever it did to look like that. My brain can't reconcile what it did to look like it does. LOL I'll add it here just to muddy the waters.