What is It?

The small self-contained marine ecosystem living on my desk continues to thrive. It currently occupies two tanks–one for the nudibranch eggs (and subsequent larvae…more on that in a few days) and one for everyone else. The reasoning for keeping larvae and all other separate is simple: nudibranchs have a reputation as marine aquarium killers, and I worry a bloom of them will offset the balance of the ecosystem too much. As it stands, the little gelato jar in which my subjects live seems stable and passes the sniff test, at least (which is to say, it smells roughly of good oysters when I take a whiff).

In addition to this, with each new observation, I find new creatures to admire and wonder about. This is true of both tanks, actually. Recently I noticed an interesting phenomenon. When I shone a side light through the water, I observed swarms of microorganisms floating to the surface around central substrates, like dandelion puffs. Under the microscope, they revealed this:

I’m not sure what the substrate is–my guess was eggs of some kind–but the thing that interested me most what the larger creature walking around in the shot. Here’s a longer shot of another one:

As the file name indicates, I think this is a barnacle cyprid. This is my best guess based on the searches I’ve done so far for marine plankton. A cyprid or a rotifer, but the fact that it has clearly defined back legs, seems to be crawling rather than swimming most of the time, makes me think crustacean over animalcule.

If it is a barnacle, this is very exciting, since I’ll soon have barnacles growing in my water (a gelato jar with barnacles in it would be the most Brooklyn thing ever). If it isn’t a barnacle (if they aren’t barnacles, I mean), then I have no clue what they are. And this uncertainty is the most exciting thing I can think of. It happens on a pretty regular basis. Stumbling on a creature I’ve never seen, never conceived of seeing before. Usually when I’m looking for something familiar. “What are you?” I find myself wondering all the time. It happened again while looking at nudibranch eggs:

I guessed initially that this was a nudibranch. Though now that I have seen signs of other nudibranch larvae, I’m not so sure.

Imagine if we were to stop stumbling on new things. Yet the longer I watch, the more it seems the well just goes deeper. This is as good a reason to keep exploring as any.



8 Comments Add yours

  1. Manu says:

    @matt: My first reaction is that the tail is a good sign that its a kind of rotifer.


    I will look at the videos more carefully; and will follow up soon.


  2. Manu says:

    @matt: Now when I look at it more closely; it looks like a Monostyla rotifer. Now the challenge is; fewer marine rotifers are known – so not that common (I am assuming this was the ocean sample), so it is going to be a marine species.

    Also; I often find myself using this identification key sometimes:

    So exciting to read about the jar of marine life. I got my own little “pond ecosystem” going on my own desk 🙂

    I am heading out to North East India next week to run some foldscope workshops. I will try to see if we can Periscope.. will send out a link.


  3. Matt.Rossi says:

    @Manu that would be wonderful! I hope I can work the conversation into my schedule.

  4. Matt.Rossi says:

    @Manu the one thing working against these guys as rotifers is that most sources I’ve looked at say rotifers are cylindrical, but these have all been flat (I’m not sure you can see it in any of the videos I posted, but when they swim away, it’s much clearer).

  5. Matt.Rossi says:

    I stand corrected…I think the second videos might be of Trichocerca marina.

  6. Manu Prakash says:

    Great find @Matt. I think you are right about the Trichocerca. I wonder what it uses this sharp tail for?


  7. laksiyer says:

    Hi @Matt. The last one is a monogonont rotifer for sure. Trichocerca is one too. The first two videos are fantastic, wonder what they are?

  8. Matt.Rossi says:

    I’ll see if I can get a high mag of one. I’m still thinking barnacles, though.

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