Dinner for three

[Microbia]

These are three Holophrya ciliates eating dead rotifer. The video is quite long but I've decided not to cut it. I increased video speed by 4 times.

[zzffnn]

Great video and good choice of not cutting the video short.

Did you use plain brightfield or a slight oblique?

Thank you for sharing!

[Microbia]

Great video and good choice of not cutting the video short.

Did you use plain brightfield or a slight oblique?

Thank you for sharing!

Thanks. Yes, this is plain brightfield.

[75RR]

Interesting video, good call on showing all of it.

[Mintaka]

Amazing video!

[billbillt]

Great video... Thanks for sharing..

BillT

[Microbia]

Thank you all.
I'm wondering if all three ciliates are of the same species of Holophrya or the large one is different from the small ones...

[Francisco]

Very nice video.
The big ciliate is, I think, Prorodon. Ciliates very "scavengers"

[Microbia]

Very nice video.
The big ciliate is, I think, Prorodon. Cilidos very "scavengers"

Thanks. I've read that Prorodon is the same as Holophrya. Now I'm confused..

[billporter1456]

Nicely done, Microbia!

At first it looked like the big one had a huge advantage with the smaller ones unable to push it aside. But then it turns out that the smaller ones, being small enough to get inside the dead rotifer, get far more food than the big one. A nice illustration of how what looks like a disadvantage can sometimes be an advantage. It also shows that in the microworld there is very little wasted.

Looks like you got your sensor fixed. Or did you use a different camera? Whichever it was, it's nice to see that you are back in business.

[Microbia]

Nicely done, Microbia!

At first it looked like the big one had a huge advantage with the smaller ones unable to push it aside. But then it turns out that the smaller ones, being small enough to get inside the dead rotifer, get far more food than the big one. A nice illustration of how what looks like a disadvantage can sometimes be an advantage. It also shows that in the microworld there is very little wasted.

Looks like you got your sensor fixed. Or did you use a different camera? Whichever it was, it's nice to see that you are back in business.

Thanks ! I got my camera's sensor replaced, so now I have to be careful and not to record long videos in order to avoid sensor overheating again.

[Francisco]

Very nice video.
The big ciliate is, I think, Prorodon. Cilidos very "scavengers"

Thanks. I've read that Prorodon is the same as Holophrya. Now I'm confused..

Holophrya and Prorodon belongs to the same order: Prorodontidae but Holophrya is included in the family Holophryadae and Prorodon in Prorontidae.
Best regards

[Francisco]

Nicely done, Microbia!

At first it looked like the big one had a huge advantage with the smaller ones unable to push it aside. But then it turns out that the smaller ones, being small enough to get inside the dead rotifer, get far more food than the big one. A nice illustration of how what looks like a disadvantage can sometimes be an advantage. It also shows that in the microworld there is very little wasted.

Looks like you got your sensor fixed. Or did you use a different camera? Whichever it was, it's nice to see that you are back in business.

Thanks ! I got my camera's sensor replaced, so now I have to be careful and not to record long videos in order to avoid sensor overheating again.

What cameras do you use?

[Microbia]

I use DSLR camera Canon eos 700D.

[Francisco]

Thanks

[vasselle]

Bonjour
Très belle vidéo
Merci pour le partage
Cordialement seb

[Microbia]

Bonjour
Très belle vidéo
Merci pour le partage
Cordialement seb

Merci!

[Bruce Taylor]

Very nice video.
The big ciliate is, I think, Prorodon. Cilidos very "scavengers"

Thanks. I've read that Prorodon is the same as Holophrya. Now I'm confused..

You're right to be confused. I'll see if I can straighten it out, a bit.

First, I believe Holophrya is a likely identification for the hungry critters you have recorded. The genus includes some well-studied histophagous (scavenger) ciliates, with a complicated life cycle featuring a variety of body sizes and shapes, including a smaller, narrower "traveling" (theront) shape, as well as a larger, but still narrow "adult, feeding" shape (trophont). As it eats, the ciliate swells up and becomes a big, fat pre-divider (protomont), which may then go on to reproduce by multiple fissions inside a division cyst. I've attached an illustration of the life cycle of Holophrya aklitolophon, from Hiller & Bardele, via Denis Lynn:

Holophrya aklitophon life cycle.jpg (31.98 KiB) Viewed 8157 times

The taxonomy has been quite messy, since Foissner et al. moved most members of Prorodon to the genus Holophrya, a bit more than two decades ago. The genus Prorodon now largely consists of ciliates previously described as Pseudoprorodon (oval to elongate ciliates with an apical mouth and a long wormlike macronucleus). Holophrya consists largely of ciliates previously described as Prorodon (typically possessing a more compact macronucleus). Telling the two apart in living specimens can be challenging because the groups are differentiated mainly on the basis of the "brosse," an arrangement of dorsal cilia that is often quite difficult to see without the help of special stains.

In any case, ciliates known historically as "Prorodon" (Prorodon ovum, P. teres, P. aklitolophon etc.) are now mostly placed in Holophrya, so your notion that the genera are "the same" is not so far from the truth.

[Microbia]

Thank you a lot, Bruce, for your detailed explanation! Now it became much clearer for me.
Yes, I read this article by Hiller & Bardele by the link you kindly placed below your video "Voracious ciliates (Holophrya)". It was very interesting to know about a life cycle of these critters. I wish I knew about that when I recorded the video, then I would try to capture an encystation process, though it might be very long to wait.

[Bruce Taylor]

It would certainly be interesting to have another record of Holophrya encystment! Literature on the group is remarkably sparse.

The restructuring of Prorodontida is a good example of how correctly following the rules of taxonomy can sometimes cause more problems than it solves (in the short term, at least). In 1994, Foissner's group discovered an inconvenient fact: in 1875, the protozoologist Fromentel had established a type species for the genus Prorodon (Prorodon niveus, which Kahl placed in Pseudoprorodon), and for Holophrya (Holophrya ovum, which Kahl puts in Prorodon). Throughout most of the 20th century, nobody seems to have noticed this! However, the rules are the rules...so, Foissner et al. duly moved most members of Prorodon to Holophrya, Pseudoprorodon to Prorodon, and Holophrya to Apsiktrata.

The result is some disruption in the natural flow of information from one generation of researchers to the next...and who knows what fresh confusions phylogeny will introduce when new genetic data become available!

Anyway, tissue-eating (histophagous) ciliates with a conical (as opposed to slit-like) anterior mouth-basket, and compact macronucleus, are in Holophrya, for the present, so your initial identification was likely a good one.