Euglena posing nicely

Charles Krebs · Post by **Charles Krebs** » Wed Dec 06, 2006 9:20 pm

These euglena can really morph into all sorts of shapes, but if you stay with them long enough they will occasionally strike a nice pose... here looking vaguely "snake-like". This one is really not all that large, measuring about 160 micron in total length.

Top image with 40X objective, bottom with 100X.

Ken Ramos · Post by **Ken Ramos** » Thu Dec 07, 2006 3:40 am

Interesting detail in that eyespot. Appears that it is made up of what may be many photosensitve components instead of being one massive unit.

puzzledpaul · Post by **puzzledpaul** » Thu Dec 07, 2006 4:24 am

... and each appearing to be approx. a single (vl) wavelength across. Fascinating

pp

thomasr · Post by **thomasr** » Thu Dec 07, 2006 9:44 am

Lovely colours again, Charles! I am curious: was it filters or colour saturation stretching or other CK magic?

Cheers
Thomas

Charles Krebs · Post by **Charles Krebs** » Thu Dec 07, 2006 10:58 am

pp... after reading your reply I got curious. Normally I don't pay much attention to res numbers, but...

With red light, my objectives na (numerical aperture) and my condensers na, my resolution limit should be somewhere around .33 to .36 micron. If I did all this correctly, the distance between two of the red "particles" in the eyespot is approx .5 micron. So it would seem that I am operating at about my limit.

Thomas... no real tricks on the color. Normally at a slider setting I like, my DIC is recorded with a strong blue/cyan coloration. But the color will change with different postions of the slider. So rather than always try to establish an appropriate custom "white balance" each time I change the DIC slider, I don't worry much about the white balance setting and just shoot everything in RAW format. Then, when I open the RAW file in Photoshop I adjust the color and contrast at conversion. Most of the time I simply use the eyedropper to make the background "neutral", but in this case I liked the look when I left a good amount of the blue/cyan in the background. Also, while the 10X and 20X objectives often give too much contrast in DIC, my 100X is rather "flat". So when the RAW file is converted in PS, I also darken shadows, and apply curves.

bernhardinho · Post by **bernhardinho** » Thu Dec 07, 2006 11:02 am

My god, those are fascinating shots. They look as if painted. A great pleasure to look at!!

Bernhard

Bruce Williams · Post by **Bruce Williams** » Thu Dec 07, 2006 1:21 pm

Just love these photos Charlie - the clarity and detail of your images are invaluable pointers for visual observation.

Bruce

Charles Krebs · Post by **Charles Krebs** » Fri Dec 08, 2006 9:30 am

Thomas... This was a different shot that I converted from RAW in PS by using the "eyedropper" to make the background neutral. That "one clicK" was the only color correction made. Other than that, some contrast changes were made. So you can see the difference. Some would probably prefer this "rendition".

rjlittlefield · Post by **rjlittlefield** » Fri Dec 08, 2006 10:18 am

puzzledpaul wrote:... and each appearing to be approx. a single (vl) wavelength across. Fascinating

I never thought much about eyespots before, but this sort of structure makes a lot of sense. There has to be some structure to the eyespot, or it would not provide direction. One possibility is a lump of units that are individually non-directional, but dense enough to shadow units on the side away from the light. I wonder if that's how it actually works?

The correspondence between size and wavelength is an interesting relationship. I have no idea whether it's functional. In any case, be sure to remember that the eyespot appears red because red is the color that it's not absorbing. Quick search of the web finds this:"The action spectrum of phototaxis corresponds to the absorbance of the eyespot with a peak at 480-500 between blue and aqua" [ref].

Fun stuff, and great pictures!

--Rik

thomasr · Post by **thomasr** » Sat Dec 09, 2006 1:17 am

What I particularly like is that the first two images showed background, flagellate and eyespot in different primary colors, with the red and green very saturated and the blue more in a soft cyan tone.

Thomas

nephiliim · Post by **nephiliim** » Tue Dec 19, 2006 1:22 pm

Great images, I found a lot of these in a local water sample, very interesting movement and morphing patterns indeed.

All the best (as allways)

Tom B

danitfrank2 · Post by **danitfrank2** » Mon Sep 22, 2014 5:23 am

Hello!

My name is Danit Cohen and I work for the extra-curricular science education unit of the Davidson Institute of Science Education, at the Weizmann Institute of Science, Rehovot, Israel.

I would like to ask for permission to use the images and video here.

for educational purposes.
Please email us back if this is permitted: danitfrank2@gmail.com

Thank you very much in advance,

Danit Cohen

carlos.uruguay · Post by **carlos.uruguay** » Mon Sep 22, 2014 5:46 am

Marvellous images. interesting discussion

Olympusman · Post by **Olympusman** » Mon Sep 22, 2014 7:51 am

Very nice. Looks like a Euglena acus.

piermicro · Post by **piermicro** » Mon Sep 22, 2014 11:53 am

Very ,very nice as usual.

Euglena posing nicely

Euglena posing nicely

Re: Euglena posing nicely

permission to use the image

Euglena