Zooplankton in a water puddle

It was a foot-deep puddle near the boundary of our large housing complex. For months no-one gave it a second look — till its wealth of gliding, writhing animal life was revealed by our foldscopes. Only then we found out that the water in this permanent puddle came from a rusty, leaking one-inch metal pipe that ran under the side-garden soil, and led to a solitary drinking water tap. This water was sourced from the Manjeera river, long considered the safest source of drinking water in our Gachibowli region of Hyderabad. The housing society acted swiftly to cut off the pipe and close the tap, saving several people from drinking the infected water. One more victory for the foldscope!

Puddle formed by the Manjeera pipe leakage

In the meanwhile we were amazed by the rich diversity of microscopic organisms (zooplanktons) in the puddle. This video takes you into the busy world of zooplanktons. Enjoy the sightseeing! The serenely gliding diatoms and oligochaete are a treat to the eyes.

Zooplankton diversity in puddle water

We tried to identify at least some of these organisms. The first to catch our eye was the longest member, the worm. From its size, transparent body and internal organ morphology, we thought it could be a member of the Phylum: Annelida and Order: Oligochaeta. Although its characteristic ‘setae’ or bristles were not visible, that could be because the worm did not make a flip or a turn, unlike the oligochaete we reported in our previous post, ‘Moss in rainwater’. There is a close resemblance though, so we guess this worm may also belong to the Genus: Chaetogaster. Please help us identify it more specifically, if possible!

Oligochaete (Chaetogaster?)

Among other members of this puddle community are at least two different kinds of rotifers. One large rotifer shows a tail-like appendage with a stretched body structure, and is most likely a Bdelloid rotifer, much like the one we saw in an earlier post from a pedestal pond in the same complex. This rotifer enters at about 30 sec from the left of the frame and makes a smooth exit from the top.

Bdelloid rotifer

The other, an oval shaped rotifer, resembles closely the members of our previously identified class of Monogonant rotifer, probably of genus Lepadella.

Rotifer (Lepadella) 1
Rotifer (Lepadella) 2

With their shining yellow internal organs the Monogonant rotifers look like microscopic goldfish, don’t they?

A major population in this zooplanktonic community are the small, shining pin-like structures — diatoms, which glide among randomly entering and exiting free swimmers.

Free swimmers

There was some green algal growth in that puddle which, through our foldscope, we confirmed as blue green algae (actually, colonies of cyanobacteria). A similar observation, with water from the same puddle, was posted by teachers of TSWREIS Mulugu school. Then we thought that these were filamentous algae but now, considering their blue-green colour and looking at some web images we guess they could be cyanobacteria.

Algal growth in the puddle
Cyanobacteria (old name – blue-green algae)

The final showstopper of this microscopic puddle community is a feeding nematode. Watch its long tubular body with tapering ends and observe its graceful feeding movements.


With mixed feelings we report that the little puddle is now fully drained. We wonder what happened to its diverse zooplanktonic population.

Ashalatha, Debashree, Jayashree

(Images and activism credit: Ashalatha)

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