MicrobeHunter.com Microscopy Forum

Hello,

since several years, I'm a enthusiastic microscopist, who is fascinated by the manifold microscopic life in ponds. Though I'm interested in all of the little creatures there, my special interest is the examination of freshwater gastrotrichs. I developed some special procedures to collect, separate and examine this little multicellular animals and I would be pleased to share them with other interested enthusiast.
Since I'm using micro-aquariums, which allow the microscopic observation of gastrotrichs in their (semi-)natural environment over several weeks, I'm trying to document the behavior and development of them. I also try to photographically "collect " as many of the 400+ freshwater species.
Perhaps there someone out there who shares this interests?

Best regard

Michael

Michel,

Would appreciated learning more on your micro aquarium.

Had my first gastrotrich in this weeks fresh water sample: quick little guy, so interested to see more of them.

Hello deBult,

in a micro-aquarium the cover slip is sealed with petroleum jelly (vaseline) so that no water can evaporate while air can pass the seal. If you take normal slides for that purpose, the amount of water is not large enough to puffer the chemical changes and the organisms will die quite soon. If you make the water film thick enough for a stable environment, the optical properties of the slide will be too bad for a good observation. So you have to make a compromise:


(Sorry for he German text, but its an old figure)

I take a slide with a depression and a "as big as possible" cover slip (e.g. 24mm x 60mm). The cover slip is pressed down to minimize the thickness of the water film while the depression provides enough water puffer. In this way you get plenty of room for a good observation outside the depression. You can even use 100x oil objectives without problems.
To seal the cover slip, I smear a small amount of petroleum jelly on the palm of my left hand and strip off small strips of petroleum jelly with all four edges of the cover slip. The cover slip is now surrounded with thin stripes of petroleum jelly. After applying the cover slip to the slide I press the edges of the cover slip down with a wooden toothpick to seal the slide. This sort of micro-aquarium keeps most of the organisms at least 4 weeks alive. You can store the slide in a normal slide box. Be sure that the cover of the box is transparent to allow photosynthesis.
As you noticed, gastrotrichs in a "normal", temporary preparation are very fast moving animals. The reason for this is, that they are permanently in panic (same with he other animals like ciliates etc.)! As the water is permanently evaporating there is a constant change of the chemical conditions in the preparation and the gastrotrichs will not calm down until they are smashed by the cover slip. This is avoided in a micro-aquarium and after some hours the critters will calm down and can be observed in their natural behavior.
The video shows some impressions in a micro-aquarium, which is some days old. At the end of the video you can seen some gastrotrichs (Aspidiophorus oculifer, Dasydydes ornatus, Heterolepidoderma majus, Aspidiophorus sqamulosus). Please note how slowly they are moving (most gastrotrich species are always moving) and how good the optical condition are.



Just give this sort of preparation a try - it's worth observing without the pressure of time!

Best regard

Michael

Like your micro aquarium, seems to work very well. Have you by any chance tried it with seawater?

I used the micro-aquarium for seawater, too. It works fine. Make sure, that you don't have any leakage - this would produce some salt crusts.

Best regards

Michael

Hi Michael,

I am an enthusiastic student of freshwater gastrotrichs. I've been working with them for about a decade. I live in the northwestern United States, and have been focused primarily on identifying local species.

Jim Kirk

Hi Jim,

great - I knew, there must be somebody else out there who like the little worms, too!

It's a hard task to identify the found species. What literature do you use? I still have a lot of candidates for which I didn't succeed in identifying to species level.
It would be interesting to compare some pictures of the same species to learn more about the variability of the species from diffrent continents. If you are interested, pleas send me a private message or an email.

Michael

Very neat aquarium. Thanks for posting.
This device might easily lend itself to continuous placement on a microscope stage with a light cycle - 12h light, 12h dark etc. Then perhaps algae and even diatoms will multiply...without the nuisance of sand and silt.

Micro-aquarium is a great idea, thanks for sharing.