Identifying a few ciliates

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rhiannontries
Posts: 32
Joined: Wed Dec 02, 2020 5:15 am

Identifying a few ciliates

#1 Post by rhiannontries » Sun Apr 11, 2021 4:32 am

I am attempting to dive into the world of ciliate identification. I have mostly used Foissner and Berger's "A user-friendly guide to the ciliates" to try to identify these guys. Needing help on some of these, so feel free to make suggestions!

1. Nassula ornata
2. Homalozoon vermiculare? or maybe Stichotricha?
3. Pretty lost on this one, maybe paramecium?
4. Some sort of hypotrich

https://www.youtube.com/watch?v=56J1WcCNQ58

Bruce Taylor
Posts: 986
Joined: Fri Sep 04, 2015 11:34 am

Re: Identifying a few ciliates

#2 Post by Bruce Taylor » Sun Apr 11, 2021 1:03 pm

Where was the sample taken? The habitat is an important clue (it narrows things down a lot!).

1. I don't think it's Nassula ornata, though it's not impossible. Usually, that species presents with numerous discrete food vacuoles, varying in colour. This critter is uniformly green, possibly from algal symbionts. I would suspect a green prostomatean, such as Holophrya ovum. However, we don't see the mouth, which is where identification of ciliates begins! If it is Nassula sp., the mouth will be on the side of the cell, and feature a basket-like structure called a cyrtos. It is Holophrya, the mouth will be at the anterior pole. If it is a green Frontonia, the mouth will be in the anterior third of the cell, and D-shaped, or peaked like a church window. And so on.

2. It has adoral membranelles, so definitely not Homalozoon. It's a loooong hypotrich. :) (How long? Measurements would help). I can see why you're thinking of Stichotricha, but it is not one of those. I wish we could see it more clearly, because it's an interesting critter! There are quite a few wormy-looking hypotrichs, many of which are found in soil (Hemisincirra, Terricirra, Circinella, etc.) The one that seems likeliest is Engelmanniella, a genus with only one common species, Engelmanniella mobilis. However, without seeing the thing more clearly, I would say only: hypotrich. If you can find more of them, I'd love to see them!

3. A rather flat litostomatean ciliate. It could be Bryophyllum (did the sample include saturated moss?). It could also be Loxophyllum.

4. It's only visible for a second or two, so we don't have much to go on. All I see is a dark ovoid form. The list of things it could be is very long. :D

rhiannontries
Posts: 32
Joined: Wed Dec 02, 2020 5:15 am

Re: Identifying a few ciliates

#3 Post by rhiannontries » Mon Apr 12, 2021 7:53 am

These were found in a soil/pond water/moss sample. The pond is presumably freshwater, but it is very near the ocean so I wouldn't be surprised if it was a bit brackish.

1. I have included some photos of what I think is the mouth (although I could be wrong). If it is the mouth, it does seem to point towards Holophrya or Frontonia. Unfortunately I think the footage is just too poor to tell.

2. I found some more of this one in that sample and tried my best to record https://www.youtube.com/watch?v=gNkgjttlbHU Urosoma doesn't seem entirely off the mark, but I am pretty much just grasping at straws here. I seem to have quite a few in this sample, so hopefully I can eventually identify this one.

So much to learn! Thank you Bruce for sharing your knowledge.
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Bruce Taylor
Posts: 986
Joined: Fri Sep 04, 2015 11:34 am

Re: Identifying a few ciliates

#4 Post by Bruce Taylor » Mon Apr 12, 2021 12:07 pm

Ah, OK. I suspected there was soil and/or moss in the sample (and if it really is salty, that changes the picture, too!). The hypotrich is probably one of the many long, skinny ones that are found in saturated soils. I mentioned a few, above, and there are many others. "Wormlike" ciliates are pretty typical of that habitat, and they tend to have names ( (Notodeviata, Australothrix, etc.) that are unlikely to appear in older sources that focus on pond and lake critters. Unfortunately, you can't identify hypotrichs by approximate body shape. Identification depends on having a clear view of features like the distribution of cirri on the cell, undulating membranes around the mouth, cortical granules, position of contractile vacuoles. Measurements are needed, too. Cell shape can rule out some critters, though. ;) Urosoma is unlikely.

The green oval guy is probably a prostomatean, likely a holophryid. In the smaller image at the bottom, we see an oral opening at the anterior pole, slightly off-centre. The oral mouth in Frontonia or Nassula would be further back, and on the side. Whatever it is, it's been gorging on algae, and the cytoplasm is so dark we can't see features that might help with identification, such as the macronucleus or oral "nematodesmata" (stiff rods around the cellular "throat").

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