MICROSCOPY- The Swamp III / one year

One year on, and there is an abundance of life in the jar, both macro and microscopic. Vegetation is now mostly on the bo ttom, and it largely consists of algae. More algae at and above the water line, on the walls of the jar. The lights have been on for the most part of the last 6 months, with maybe 48h of darkness in total. Temperature has been a steady and warm 22-24°C.

A superficial visual inspection with the unaided eye shows much activity, with a plaetoria of ostracods happily swimming around looking like they own the Swamp (they totally do). Intelligently estimating their number is an interesting exercise for which I am too lazy right now, but a quick guess would be several hundred of the larger specimens (0.5mm+) and thousands of the smaller ones.

This was filmed with a phone through the wall of the jar and I may have cropped:

Much activity visible with the naked eye – ostracods everywhere

This is a 1.5cm piece of wood at the bottom of the jar. Footage is from above, through the hole for collecting samples:

Ostracods on a 1.5cm piece of wood

The algae colonised the walls of the jar to the point of becoming quite opaque at one point, but then died and peeled off after about 9 months. The walls are now very clean (below the water line).

The most abundant micro-organism is a species of ostracod. This is a fresh water crustacean that lives inside a clam-like structure composed of two valves articulated on the dorsal side that swims around by agitating its antennae and claw-like appendages. Judging by their numbers, the Swamp contains no predators for this creature.

They move about quite rapidly and seem to rely entirely on touch. I saw no interaction between individuals apart from the occasional bump.

They are small enough to become transparent when backlit so internal structure becomes apparent quite easily:

The outside of the shell seems to be covered in what looks like fine hairs:

A different perspective at lower magnification:

And a close-up of its lovely face:

Now this is the interesting bit. I found this pair of paramecia that was twirling around in the same place, not moving about like their friends, and that seemed to be tied together in some way:

Paramecia have largely come to dominate the micro-organisms in the jar, their numbers now far exceeding rotifers, of which I only saw one:

Nematode worms continue to live in the substrate and range from very large ones (cm) to smaller, more agitated specimens. I cannot say whether there is one species of more.

The only rotifer I found. It was not feeding and I only saw it moving about. They used to be the dominant kind of micro-organism for the first 6 months or so.

This is a bug that I see for the first time. It’s large, about the size of the bigger ostracods (1mm) and there seem to be quite a few of them.


As the lightbulb regularly needs replacing I decided to stick it in a wine cork and allow for replacement without unsealing the main cover of the jar.

This came after my first attempt to change the lightbulb without unsealing resulted in catastrophic failure, as can be seen in the photo showing the lightbulb on the bottom of the jar.

The Swamp III is not a closed system, strictly speaking. I am not 100% sure the cork top is perfectly sealed to the glass of the jar and I have completely removed the top three or four times. I also made a hole for collecting samples that I open every time I do so. I have also added several mm3 of starch sometime in early winter. I give it non-stop light and temperature is steady at 22-24°C in winter and 24-30°C in summer.

This being said, it does its own thing in there and provides for excellent observation material. A great little toy.

This is an example of a sample that I collected, with some water, stuff from the side of the walls, from the surface of the water, from the bottom and from the substrate.

The camera records afocally through the microscope