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Nope, not Paramecium. It is another hypotrich. That transparent zone at the anterior of the (very flexible) cell is the cavity surrounding the mouth (in Paramecium species, the buccal opening is usually close to mid-body).

Ah, much clearer. This is a hypotrich ciliate, in the family Oxytrichidae. It could be a species of Cyrtohymena , which has a distinctive mouth cavity...sort of teardrop-shaped and very transparent in the middle, with the undulating membranes arching over. The other possibility is Steinia (e.g. Stei...

Hah! That's great!

It's not Paramecium . I'm sure you'll run into those soon enough and then get tired of having them around. :D Unfortunately, we don't see this critter very clearly. It has a big lateral buccal cavity, in the anterior of the cell, and (I think) a large undulating membrane. Single contractile vacuole,...

As I noted on iNaturalist, it's a sessile peritrich ciliate that has come loose from its stalk. The dark cytoplasm and somewhat baggy cell shape are consistent with Vorticella campanula, but without seeing the stalk I wouldn't identify this below order Sessilida.

Rossf wrote: ↑

Sat Mar 20, 2021 9:33 pm

do you have a particular microbe that really catches your fancy?

Ciliates.

That's a lively fellow. Perhaps Arachnula? But that's just a shot in the dark...I'm not an amoeba guy and can't even decide whether the pseudopods are granulose. Ferry Siemensma's site is the best resource for critters like this: https://www.arcella.nl/visual-key-naked-amoebae/

Very pretty. Re. the ciliate at the end, it is probably a colpodid, but we don't see enough detail for a genus-level ID (let alone a species). It could be Colpoda, but could also be Bresslaua, Krassniggia, Kuehneltiella, etc.

Yes, it is probably a species of Uroleptus in the limnetis complex. To rule out Strongylidium you'd want to see the arrangement of cirri.

Nice clear footage! These are Euplotes.

Yup, Pleuronema. You're right to look at the caudal cilia, but P. coronatum has long ones. It is P. crassum that lacks elongated caudals, and that seems to be what we have here.

Chilodontopsis would have a cytopharyngeal basket (cyrtos), supporting the mouth. I don't see anything like that, here. When the critter eats a chunk of algae (in the final seconds of the last video) it seems to take it in at the margin of the cell. A large posterior vacuole is a fairly common char...

And here is a single-celled critter (a warnowiid dinoflagellate) with a complex eye, complete with light-focusing lens! Convergent evolution in action. ;) Ocelloid.png (source: https://bmcecolevol.biomedcentral.com/articles/10.1186/1471-2148-9-116) Don, the Euplotes in your first image is not known ...

Giant vacuoles are a common deformity in ciliates. It's hard to tell what this one is, but there are probably more of them in the same water. The big vacuole is not a normal feature.

Beautiful microscopy! Tetrahymena, I believe.

Frontonia acuminata typically has a concentration of pigment (black spot) in the anterior of the cell, rather than the posterior, but this could just be an anomalous individual. We don't see the mouth very clearly, but it does look like Frontonia ...flattened cell, slightly acute at the posterior, ...

Yes, a true heliozoan (in Centrohelea, Centroplasthelida or Heliozoa, depending on your favorite taxonomic scheme). We see an outer layer of tangential plate-scales and a rigid spike-scales. Identification below phylum usually requires a clear view of the scales themselves.

It's a "limax" (slug-like) amoeba with a conspicuous uroid and posterior vacuole. Pseudopod formation is non-eruptive, so it's amoebozoan, not heterolobosean. No hyaline zone at anterior. I couldn't make out a nucleus (moving too fast :D). Info on size might be helpful, but I think Saccamoeba sp. is...

There are quite a few possible causes of membrane rupture. It can happen after contact with a noxious chemical, or as a result of osmotic disregulation, or because of coverslip pressure. Ciliates often sustain damage when they come into contact with an air bubble, especially at the edge of the cover...

The image is a bit murky, so it's difficult to see whether it has a layer of hard scales & spicules (periplast) around the cell, in which case it is a true heliozoan (such as Acanthocystis , Choanocystis , etc.). It could also by an actinophryid, as D0c suggests. Actinophrys is a "heliozoan" in the ...

Oh, and re. "sketches and literature"...the most comprehensive source is Monograph of the Dileptids , by the late Wilhelm Foissner and Peter Vdacny. It is a thorough taxonomic revision of the group. You can download the book directly from Foissner's website, here: https://www.google.com/url?sa=t&rct...

I think Parapodophrya soliformis is likely. The surface of the thing is quite knobbly, and the tentacles look "webby" at the base.

As for the greenish thing, it doesn't seem to have tentacles at all, so it is not a suctorian. I'm not sure what it might be. An egg, maybe?

This is a dileptid that happens to have a deformed posterior. A flattened, spatulate tail is not a trait found in any normal dileptid. So, that feature can safely be discounted. Monilicaryon has only one species, Monilicaryon monilatum (= Dileptus monilatus ), which can be identified by its monilate...

Yes, Stentor polymorphus (string-of-beads macronucleus, zoochlorellae, no cortical pigmentation). Nice clear videos.

The jumping ciliate at 4:19 is Askenasia.

I can't help with the square-looking algae (not in my wheelhouse ).

So yes, this is Loxodes magnus . Your guys are in the middle of the size range for the species (and well above the top size for L. rostrum ). They can easily reach 800 μm. Here's a 750 μm guy I filmed a few years ago...looks remarkably like a whale in the second half :D : https://www.youtube.com/wat...

Very nice! The color and apparent size suggest Loxodes magnus. Do you know how long these were?

Colin R. Curds revised several suctorian genera, back in the 80s, and the texts are still quite useful. Here's the one for Podophrya and its kin: https://www.biodiversitylibrary.org/part/8103 Prodiscophrya isn't included in that one, though (different family!). It was another book by Curds that aler...

Nice! :) The only well-described Parapodophrya in freshwater is P. soliformis , which should have a somewhat spiny appearance on the outer surface of the cell, and a widening of tentacles at the base. Higher magnification would be useful, here, because I can't decide whether I see these traits. :) O...

If you look closely at the Supraspathidium in that old video you can see that the anterior of the cell is neatly "squared off", not ragged, and at there is a sort of rim around the slit mouth (it looks like blubbery lips). Just behind that, supporting the mouth-slit, there is a fan of "nematodesmata...