Foldscope Day 5: A Water Flea from Hauz Khas, Delhi

After many attempts at imaging life in pond water, I finally chanced upon a tiny swimming creature. Thanks for all your helpful tips, which really came in handy.

Here’s a video of what I saw:

I was super excited to see this (you can probably hear that in my voice). I posted a quick video on twitter and asked for help identifying what I was looking at, and quickly learned that this was a water flea, possibly a Daphnia. (Thanks to Shreya Dasgupta, Subhojit Roy, and his 8 year old son Vijay for help identifying it.)

I love the detail that you can make out with the foldscope. You can clearly see the compound eye (reddish center in a black circle), the pouch with eggs in it (wow! So this is a female, and she’s a mom), the tail with what seem to be hairs at the tip (I wonder what their purpose is?), the beating mouth parts, and the antennae beneath the creature.

This creature was a former resident of the Hauz Khas Water Tank in Delhi, a structure with a rich history that traces back to the 13th century, when it was created as a water reservoir for Delhi’s newly built Siri Fort.

GPS pin of where I sampled the water

Today, the water in the reservoir has an alarmingly bright green color, and is home to many kinds of aquatic birds. I’ve long wondered what’s in the water, and the foldscope gave me an opportunity to find out first hand. So I collected a jar full of water from the reservoir and put a drop under the foldscope.

hauz khas water jar

This Hauz Khas complex (the reservoir and the adjoining parks and monuments) are a threatened oasis of biodiversity among densely urban surroundings. Here are some pictures of the reservoir to give you a sense of the place. I feel like the half-sunken boats and garish green water lend this place a distinctly post-apocalyptic vibe.





What do you see in the water flea video? Post a comment with your thoughts / observations / ideas.

4 Comments Add yours

  1. laksiyer says:

    @Aatish. Really nice video. Yes its a Daphnia, although it is dead. The brood pouch is really nice and you can see eggs inside. Other features of the crustacean are well defined to allow identification to the species level. Will look up my guide and revert if I can pinpoint a binomial name.
    The lake is completely eutrophic and I am even surprised these Daphnias are there.. Perhaps this is the silver lining that if attempts are made the lake might be resurrected.

    Did you find out what the basis of the green color is? It looks very strange to me. Normally one would have seen hundreds of eukaryotic alga and in any microscopic sample. In your sample this far I didnt even see one. IF possible can you image the algae which contribute the green color. Can you measure the pH of the water sample? Its a pity that the water body has been destroyed like this, it looks like a pretty large one.

  2. aatish says:

    Hi @laksiyer. Thanks for that knowledgable comment. I didn’t realize I was seeing a totally dead lake.. that explains why I’ve been struggling so hard to find anything living in the water. Meanwhile have been seeing a lot of microplastic pollution (tiny strands of plastic). Sad. Also I could see waste water being dumped into the tank from restaurants nearby, so I imagine the condition of the lake is deteriorating further.

    I couldn’t see anything I could recognize as algae in the water, instead I saw a bunch of clumps like this one
    Do you happen to know what that is? I thought they might be cyanobacteria colonies but I don’t really know.

  3. laksiyer says:

    Hard to say, they might be picoeukaryotic algae too. They do look photosynthetic. I did see an alga in that (green). If you see them again, try the high power and you might see intracellular structure and that might help. The colony looks pretty interesting, if it is from a water sample and not a solid substrate. Perhaps you can do a time lapse and see how it grows or moves?

  4. Matt.Rossi says:

    @Aatish my word, what a gorgeous image of that daphnia. Strange to think that it’s dead, but so beautifully preserved as it was.

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