Wonder-worms in a pedestal pond

Apr 03, 2020 • 4:50 AM UTC

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Microorganisms

TCIS Outreach

We are a group of students, volunteers and staff working with TIFR Hyderabad's Science Education and Outreach program: http://www.tifrh.res.in/~outreach/

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One fine spring morning, my nephew called me to show something ‘interesting’ in a pedestal pond in our housing society. When I reached there, I saw a beautiful lotus blooming and some dry lotus leaves around (they looked curled up or folded). It seemed that they were being stitched together to make a home… wonder who could be the home-makers?

When I asked him if this was what he had summoned me for, he pointed to some parts of the pond. Oh! There were so many worms, clusters upon clusters wiggling away.

It was a spectacular yet eerie sight. This was very new to me as well, although I had explored the microcosmos in the same pond earlier as well. The body of these worms seemed segmented, so I thought they could be annelids. When we tried to touch the worms with a small stick they immediately disappeared. By this time a small group of residents had gathered around us, lamenting about the maintenance of the pond. Secretly, we were delighted by the “wealth” in it!
When I returned to collect samples from the pedestal pond, the gardener had probably cleaned it because the algae on the surface and the folded lotus leaves were removed. The worms were still there. I tried to collect them but each time I inserted the dropper in the water, the worms retreated to the bottom. I finally just collected the water around the place where I had last seen the cluster of worms.

Under the Foldscope, I saw this water sample had small worms with a segmented body and setae, yes! They are Annelids, Aeolosoma sp.
I discussed my findings with Chandrika and showed her the pond. She too tried to capture one worm out of the hundreds we saw in the pond, in vain. Finally, we carved out a slice of the soil with the help of a garden spade… it wasn’t easy at all, since the roots of the water plants were well networked, but voila! We found two worms there!

Upon a frantic Google search, we learnt that these are Tubifex sp . an oligochaete which belongs to Annelida. These worms stand in the water upside down i.e. their head is attached to the soil while their tail wiggles around in the water to capture oxygen through the skin, i.e cutaneous respiration. They can apparently survive in low oxygen conditions (sewage water too!) since they have a lot of haemoglobin. (Reference: Wikipedia ) The water in our pedestal pond actually comes from our sewage treatment plant.

I placed one worm on a slide and started observing it.

In the beginning, it was difficult to take the video as the worm was very active.

After 5-6 hours its movement slowed. In this video, we can see the long reddish worm.

We can see the expansion and contraction of its body wall and coelomic fluid as it is moves.
I was keen to see if the worm would survive with just a drop of water. Can they actually survive with less oxygen? I happened to check after 27 hours and my dear worm was still moving! Its activity, however, had further reduced and the tail end was now pale (in contrast to being bright red earlier).

In this video, I tried focusing on its tail end part. The sudden twisting and stretching shows that the worm was trying to cut/amputate that part of its body. Am I correct? After 2-3 hours, dear Tubifex was no more.

Do you think that the worms found in this water sample are baby Tubifex or some other worms? One way to tell is that we can see oil drops in the Coelomic fluid, which confirms that these are baby Aeolosoma sp..

This water sample is rich in biodiversity. Other microbes I observed are Euplotes , rotifers, copepods , Halteria sp. , Phacus sp . and half-moon shaped microbes.

For copepods see the previous post here .
Here you can see the half-moon shaped microbes. Can anyone help to identify these? Are they Desmids?