Fanworm-like ciliate(?). Need help with species, please.

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reakeener1970
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Fanworm-like ciliate(?). Need help with species, please.

#1 Post by reakeener1970 » Fri Aug 28, 2020 2:44 am

Hi.
First time post. Thanks for any assistance. I have searched quite a bit using my couple of books and Google Lens with some photos, but haven't been able to get a good identification of it yet. It waits in a sort of extended state with long ciliate "whiskers" extending around its mouth(?) -- or at least what seems to function as a mouth. Occasionally when some particle or euglena happens by, it suddenly draws its "whiskers" into its "mouth," shortens and widens its body into the shape of a lemon. After a couple seconds, it goes back to its extended, ready to feed state. It seems anchored to the bottom of my slide at its posterior end and does not move its body around except for its contracting and extending motion. I usually suck it up from water in my bird bath. I think is is single-celled, but might be a rotifer or a larval stage of something. Extended is is maybe 250-300 microns. Contracted maybe about 200 microns. (Best guesses.)
A couple photos attached. Thanks! :)
-Ted
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IMG_20200827_125541.jpg (65.23 KiB) Viewed 3213 times
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IMG_20200827_125228.jpg (16.96 KiB) Viewed 3213 times

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janvangastel
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Re: Fanworm-like ciliate(?). Need help with species, please.

#2 Post by janvangastel » Fri Aug 28, 2020 6:33 am

Looks like a vorticella to me. They can retract very quickly and then stretch out again and open their mpouth to feed.

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KD Arvidsson
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Re: Fanworm-like ciliate(?). Need help with species, please.

#3 Post by KD Arvidsson » Fri Aug 28, 2020 7:32 pm

Or some rotifer maybe! Interesting :D
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reakeener1970
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Re: Fanworm-like ciliate(?). Need help with species, please.

#4 Post by reakeener1970 » Fri Aug 28, 2020 10:04 pm

I should also add the the whisker-like mouth ciliae(?) do not move in a rotifer or vorticella-like way with constant motion. They stay open and fairly still until they are triggered, at which point they spring together and get pulled into the body/cell. Or, at least, that is what it looks like. I also cannot see any fine ciliae on its body, just the front whiskers. It does not generate currents around its body as far as I can tell -- it just waits until something drifts into its mouth, or whatever. Hence my marine "fanworm" analogy. I can see it better than my poor attached photos might indicate. It appears to have a large vacuole.

Bruce Taylor
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Re: Fanworm-like ciliate(?). Need help with species, please.

#5 Post by Bruce Taylor » Sat Aug 29, 2020 11:57 am

This is a peritrich ciliate in the order Sessilida, without question. We see the characteristic anterior wreath of cilia, a domed peristome, and a contractile vacuole near the peristomial rim. You note the lack of somatic cilia, which is typical of peritrichs (except when they are in the "swarmer" phase of life). At the posterior of the cell we see a structure called the "scopula", which is used either to secrete a stalk or attach directly to the substrate. This one is distinctly corrugated and quite wide, which probably suggests a rather broad stalk (as in epistylids and operculariids, for instance) or possibly a direct attachment point (as in Scyphidia).

We don't see the stalk or a connection to the substrate, so identification to genus is not possible.

It might be a species of Opercularia, because the contractile cell seems to have no peristomial lip, but we would need to see the organism more clearly to identify it even to family. I don't think it is Vorticella.

reakeener1970
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Re: Fanworm-like ciliate(?). Need help with species, please.

#6 Post by reakeener1970 » Sun Aug 30, 2020 2:29 am

Thanks Bruce! Brilliant! I agree 100% after looking up the information you provided. I watched a couple more today that I found and a.) DID finally see a long stalk on one attached to an algae filament, and b.) DID notice some water currents it was generating at its mouth that I did not see before. As you said, I do NOT notice a peristomal lip that I see in the images online of Opercularia, but will make sure that isn't something I'm missing next time I see one. The stalk I finally saw today was fairly thick relative to body size and somewhat convoluted (not threadlike and straight). The ones I have seen so far do not seem to grow in groups/clusters like Opercularia ampluscolonia.
Thanks again for getting me going in the right direction!

Bruce Taylor
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Re: Fanworm-like ciliate(?). Need help with species, please.

#7 Post by Bruce Taylor » Sun Aug 30, 2020 11:28 am

reakeener1970 wrote:
Sun Aug 30, 2020 2:29 am
I do NOT notice a peristomal lip that I see in the images online of Opercularia
The lack of a distinct lip at the anterior of the cell is a handy feature that can be used to differentiate Opercularia from Epistylis (which always has a lip, but only in the non-contracted state). Most operculariids also have a retractible disklike structure, raised above the peristomial area on a stalk when the organism is feeding. However, this "operculum" is not always deployed, and has been lost in some members of the family, so the lack of one isn't a bullet-proof diagnostic character.

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