Phantom Midge larva (Chaoborus). "Glassworm"

[Charles Krebs]

Can't believe it's been about three months since I last posted an image! Looks as if there have been many great images put up during that time. Hope to cruise through them soon.

Here is a subject I had not photographed before. It is the larva of a Chaoborus midge. In regular light it is strikingly different in appearance from most other midge larvae... extremely clear and transparent. Hence the common names "glassworm" and "phantom". The body appears to be completely empty except for two air-bags of expanded tracheal tubes... one fore and one aft. These air-sacs allow the larva to maintain it position in the water column (or move up and down) with very little wriggling movement.

With cross polarized light, or with DIC, the "clear" body shows an astounding number of muscles and internal organs... a remarkable change in appearance.

Under the microscope one of the most amazing features of this creature is the prehensile antennae which are used to capture prey and hold it in position while the jaws (seen pretty clearly in the second shot) do their work.

First two images are crossed pols with a lambda plate (4X and 10X objectives). Second two are DIC (10X and 40X objectives). The last is DIC dialed up to "Disney-color" range .

[Litonotus]

great as usual (: Chaoborus is my 'winter' specimen, I can buy it in any pet shop as a fish living food (:

[Jacek]

Pictures perfect as always, the second similarity I find most

[discomorphella]

Hey Charlie,
Spectacular find. And as a bonus, an animal whose musculature has its birefringence optical axes either parallel or 90 degrees to your QWP's.
This will become my new standard illustration of optical axes for those who ask, I'll just send them here...

David

[Cactusdave]

Lovely images Charles. Graham Matthews and I had an enjoyable time photographing these fascinating larvae at the recent microscopists weekend at Juniper Hall in the UK that we attended. I think Graham has already posted something on the weekend.
At times I think we got into a little healthy competition with our efforts ! I'm away from base at the moment and don't have access to my images, but when I return next week I will post some, including some multi-image stitches. Like you I used crossed polars +/- retarders, and later with a specimen I took home with me I used DIC.
One thing I was particularly interested in was the fine structure of the paired buoyancy organs, when they were "deflated" by allowing the coverslip to compress the specimen a bit.

[Ernst Hippe]

Charles,
this is a brilliant example, that polarization with retarders is not only a question of esthetics but often a very useful tool on biological objects.
Thank you! Ernst

[Franz Neidl]

Hello Charles,

during the 3 months I was missing you and now I am happy that you are back in the forum.
The pictures are very interesting - of course.
I have a question. You write aboute a lambda plate. I was looking in Internet about their prices. The cost is between 300 and 400 Euros. My question is: Is it necessary to have these (professionell) lambda plates or can I use also plexiglass or plastic-material? What is the disadvantage of plastic foils and plexiglass?

Franz

[Cactusdave]

Proper quartz wedge or mica wave plates intended for microscopes come up fairly frequently on EBay at much lower prices than this, just make sure they will fit the slot in your microscope. I must say that though I have a proper quartz wedge retarder, I usually use plastic retarders, bought or scavenged. The wrappers on CDs and greetings cards are often particularly effective and two layers of Sellotape superimposed and mounted on a slide, make an excellent retarder.

[RogelioMoreno]

Charlie,

Beautiful set!

Rogelio

[Charles Krebs]

Thanks all... feels good to finally get some of the dust off of the old BHS!

Franz...

I have a question. You write aboute a lambda plate. I was looking in Internet about their prices. The cost is between 300 and 400 Euros. My question is: Is it necessary to have these (professionell) lambda plates or can I use also plexiglass or plastic-material? What is the disadvantage of plastic foils and plexiglass?

The analyzer slider I use does not have have the channel for inserting a wave-plate, nor do I have provision for one in the nosepiece.

So when I do this type of image I use inexpensive retarders over the base light port. First I use a polarizer directly on the base light port (Edmund Optical Techspec material), then I place the retardation "film" on top of that. (I don't use the condenser polarizer since the wave-plate needs to be between the two polarizers and I have no place to do that if I use the condenser polarizer). The disadvantage is that it is a bit of a "kludge". But for purely visual usage with biological specimens like this one, it does actually have the advantage of the freedom to move the wave-plate "axis" in any direction. This allows you to "fine tune" the visual effect as desired.

Since the wave-plate is not in the imaging path when used this way, it will not degrade the image quality, and the plastic ones seem to work just fine.

The one I use most is an Edmund Optical #27-048 (2 pieces 2"x2", 1λ Retardance, $15). They used to sell 1/2λ and 1/4λ pieces as well, but I no longer see them listed on the Edmund site. Another source for similar pieces is Knight Optical in GB:
https://www.knightoptical.com/php/brows ... 08&catClr=

If you have a slot to insert an "official" DIN microscope plate, you might want to see if you can locate a Motic dealer and get a price on their 1λ tint plate #01006700151. These typically sell new for less than $100. (And of course there is always used on Ebay. But many of the older ones are not the proper size frame).

[johan]

The top two are really fascinating images, it's not often I see something that's totally new to me! Made my evening =)

[Planapo]

Wow, I can't imagine a Chaoborus larva being photographed any better than this!
Once again I am gobsmacked by your awe-inspiring photography, Charlie!

Motivation for me for the winter to come to try hard to get as near as possible to your no. 3 from above.


--Betty

[arturoag75]

Superb job

[Ecki]

Very nice!

[gpmatthews]

Great images - after Cactusdave's comments I fear you have really started something...