Marine Diatom ID?

Tardigrade37 · Post by **Tardigrade37** » Sun Nov 29, 2009 8:55 pm

Hi all,
I regularly see these diatoms in marine samples, but I have yet to ID them. Anyone have any suggestions? In this sample, they were attached to the rhodophyte alga, Ceramium. Thanks!
Chris

Planapo 63x/1.4 DIC, stack of 3, crop.

Plan-Neofluar 40x/1.3 DIC, stack of 43.

Planapo 63x/1.4 DIC, stack of 178(!).

Charles Krebs · Post by **Charles Krebs** » Sun Nov 29, 2009 10:27 pm

Hi Chris...

Licmophora (genus)?

Cactusdave · Post by **Cactusdave** » Mon Nov 30, 2009 1:58 am

Very nice pictures. That Planapo X63 is an exceptional lens.

Cactusdave · Post by **Cactusdave** » Mon Nov 30, 2009 4:06 am

A couple of questions Chris. I assume both these excellent high NA lenses are oil immersion and this is a Zeiss setup? I wonder how you achieved such tiny focus increments to need 178 in the final stack with the X63 PLanapo? I would have thought that even with the smallest division increment on the fine focus, that 178 of these would have more than focused right through the subject, at this magnification.

Tardigrade37 · Post by **Tardigrade37** » Mon Nov 30, 2009 8:47 am

Charles Krebs wrote:Hi Chris...

Licmophora (genus)?

Thanks Charles! A quick google search provides some excellent images of these diatoms in similar colonial formations (the best of which have been taken by members of this forum

) - they sure are photogenic!

Cactusdave wrote:A couple of questions Chris. I assume both these excellent high NA lenses are oil immersion and this is a Zeiss setup? I wonder how you achieved such tiny focus increments to need 178 in the final stack with the X63 PLanapo? I would have thought that even with the smallest division increment on the fine focus, that 178 of these would have more than focused right through the subject, at this magnification.

You are correct Dave, both of these lenses are oil immersion and they are on my Zeiss Axiovert 200M stand (see here for details on the set up). My stand is entirely motorized and driven by the Zeiss software, Axiovision, so it can step down to the nm range - if my memory serves, I believe I acquired the 63x images at 240nm intervals, for a total depth of approximately 43 microns. This depth certainly fits with the diameter of the Ceramium. I hope this helps to answer some questions.
Cheers!
Chris

Shamefully, I forgot to mention earlier that these stacks were compiled with Zerene Stacker PMax and then were cleaned up to reduce background clutter and dust spots.

rjlittlefield · Post by **rjlittlefield** » Mon Nov 30, 2009 9:12 am

Chris, thanks for the additional information about the stacking. I have not worked much with this sort of high aperture high magnification lenses, so I'm curious also whether such fine steps are really needed. Would the result have been significantly different with say 480 nm, or 960 nm?

--Rik