Larval fish. Diatom.

[Charles Krebs]

Looking through a saltwater sample I found a very small larval fish. The body (if it were stretched out) was less than 3mm long and the head (top to bottom) measured 0.68mm. What really caught my attention was the eye which had unusual blue/metallic crystal-like structures. Here's an "overall" shot, and a tight detailed shot of the eye.

Olympus BHS, 4/0.16 S Plan Apo + 1.67 NFK photoeyepiece, Canon 50D. Darkfield illumination.


Olympus BHS, 20/0.70 S Plan Apo + 1.67 NFK photoeyepiece, Canon 50D. Brigfhtfield illumination.



Today's diatom was common in this sample (no ID). I was fascinated by the honeycomb structure and the fastening mechanisms.

Olympus BHS, 60/1.40 S Plan Apo + 1.67 NFK photoeyepiece, Canon 50D. DIC illumination.


Olympus BHS, 60/1.40 S Plan Apo + 1.67 NFK photoeyepiece, Canon 50D. DIC illumination.

[len]

Amazing
How do you measure the length of such tiny object?

[BJ]

Hi Charles,

The diatom is Stephanopyxis and almost certainly S. turris. There is just a possibility that it is S. palmeriana which has larger "pores" on the cell ends than on the sidewall...cant be absolutely certain from your photos.

Who needs a scanning electron microscope when you can produce an image like the last one !

Fabulous,

Thank you,

Brian

[Franz Neidl]

Hallo Charles,

I am very impressed by your pictures - specially from the last.
I would like to know why your last picture is monochromatic. Did you photograph this diatom in a restricted (limited) wavelenght in order to increase the resolution?

Franz

[Charles Krebs]

len,
Pretty simple. First you need to "calibrate" to find out exactly what magnifications your microscope provides. This can be done using a stage micrometer, which is a special slide with extremely accurate finely spaced lines. Then you can use either an eyepiece reticle, or (as I do) measure from the image. Once you know the magnification and the sensor size (and pixel dimensions) you can do it a number of ways. There is software for microscopy that can provide measuring capabilities. I simply use the ruler in Photoshop to get the dimension in pixels and relate it to this spreadsheet:
http://www.krebsmicro.com/scale_bars.xls

BJ,
Well, I often look enviously at the resolution of SEM, especially with subjects like pollen and empty diatom frustules . But there's nothing quite like viewing with natural colors and seeing live subjects move about.

Franz,
No special reason. I like b+w, and since this was an empty frustule there was absolutely no color information to portray.