Podosira stelliger, a marine diatom

René · Post by **René** » Tue Nov 15, 2011 5:16 am

Hi guys. here's a serie of images from Podosira stelliger, a marine diatom from the Nothsea. It has typical chloroplasts that in preserved material (lugol) generally not show their beauty (generally too densely packed). But here, in this winter material it shows up pretty well. Even though lugols generally gives some shrinkage of the cell contents (last image!), it gives good preservation for routine samples.

Podosira (and related Hyalodiscus) shows a typical areolation pattern where the middle-part of the valve seems clear. At high magnification however you can detect structure, which does not permeate through the whole of the siliceous wall. The following images are cropped images at top, middle and lower level of the siliceous wall.

Best wishes, René

Mitch640 · Post by **Mitch640** » Tue Nov 15, 2011 12:47 pm

René, they are very beautiful. Wouldn't it be nice if they were big enough to hold in your hand?

René · Post by **René** » Wed Nov 16, 2011 4:16 am

Absolutely Mitch! Plenty of scientists turn to arts, in retirement. That's a way to make the beauty of creation touchable.

Best wishes, Rene

Jan l'Amie · Post by **Jan l'Amie** » Wed Nov 16, 2011 6:38 am

Ask Wim van Egmond about it. He is an artist with science !!

He is also a member of Nederlands Genootschap Voor Microscopie.

BJ · Post by BJ » Wed Nov 16, 2011 9:35 am

René,

beautiful photos - thank you! I particularly appreciate the view of the cytoplasmic strands. This species has appeared in my net samples (south of Portugal) yesterday for the first time since Spring. It is nice to have a species which is easy to identify with confidence!!

In my specimen (live), the chloroplasts are much more tightly packed.

muito obrigado !

Brian

René · Post by **René** » Thu Nov 17, 2011 4:18 am

BJ wrote: This species has appeared in my net samples (south of Portugal) yesterday for the first time since Spring.

yes, when the weather turns rough, they start appearing again

BJ wrote: It is nice to have a species which is easy to identify with confidence!!

Hmm, I thougth so too, but there are Hyalodiscus sp that look pretty much the same. I have to look more closely into that!

BJ wrote: In my specimen (live), the chloroplasts are much more tightly packed.
Brian

Absolutely! Following img shows the normal packing in stereo, for our cross-eyed enthusiasts

Best wishes, René

Mitch640 · Post by **Mitch640** » Thu Nov 17, 2011 4:27 am

When these are alive and active on the slide, do they move, like the other diatoms do?

René · Post by **René** » Thu Nov 17, 2011 5:20 am

nope. Generally they use a raphe for moving around, centrics like this one don't have that.

Best wishes, René