A Vorticella breaks free from its stalk and swims away

billporter1456 · Post by **billporter1456** » Tue Mar 25, 2014 5:01 am

I was peering at a Vorticella yesterday and was watching as it starting rotating. Not knowing what function this rotation might have, I kept watching as it broke free from its stalk and swam away. Maybe the rotation is what allowed it to detach from the stalk? Maybe someone will chime in with a comment or two.
https://www.youtube.com/watch?v=9d1cIuVQb1k

carlos.uruguay · Post by **carlos.uruguay** » Tue Mar 25, 2014 5:10 am

Bruce Taylor · Post by **Bruce Taylor** » Tue Mar 25, 2014 7:09 pm

Another fun video.

That guy (who is either Vorticella or Pseudovorticella...can't say which) might be having a little trouble with osmoregulation. The bulging peristomial disk (that "domed" surface at the top) is something you often see when the coverslip is weighing a little heavily!

This convexty is sometimes given as a taxonomic feature for certain species; however, as Warren notes, "most species react to unfavourable conditions by becoming increasingly globular and developing a protruding disc." (A Revision of the Genus Vorticella, p. 4) In my opinion, that's what we're seeing here.

The axial rotation might be that desperate, spinning thing that many ciliates (not just peritrichs) seem to do when they are in distress. You often see it in ciliates before they start to "bleb." When vorticellids are under stress, they do leave their stalks behind. However, this isn't the orderly departure we see when a peritrich grows a posterior wreath and becomes a ramblin' freewheelin' telotroch, but something more like what happens to a strand of seaweed in a violent ocean storm.

billporter1456 · Post by **billporter1456** » Tue Mar 25, 2014 7:14 pm

carlos.uruguay wrote:

Thanks, Carlos!

billporter1456 · Post by **billporter1456** » Tue Mar 25, 2014 7:31 pm

Bruce Taylor wrote:Another fun video. That guy (who is either Vorticella or Pseudovorticella...can't say which) might be having a little trouble with osmoregulation. The bulging peristomial disk (that "domed" surface at the top) is something you often see when the coverslip is weighing a little heavily! This convexty is sometimes given as a taxonomic feature for certain species; however, as Warren notes, "most species react to unfavourable conditions by becoming increasingly globular and developing a protruding disc." (A Revision of the Genus Vorticella, p. 4) In my opinion, that's what we're seeing here.

The axial rotation might be that desperate, spinning thing that many ciliates (not just peritrichs) seem to do when they are in distress. When vorticellids are under stress, they do leave their stalks behind. However, this isn't the orderly departure we see when a peritrich grows a posterior wreath and becomes a ramblin' freewheelin' telotroch, but something more like what happens to a strand of seaweed in a violent ocean storm.

Bruce, thanks for your comments. For what it's worth, that organism looked larger than the Vorticella I have seen in other samples. And the bulging peristomal disk was something I don't recall seeing before. It just struck me that there would have to be some mechanical process that allowed the detachment from the stalk and that rotation seemed to me to be a likely candidate. I found a couple of other videos showing detachment and saw rotation in one of them.

Bruce Taylor · Post by **Bruce Taylor** » Wed Mar 26, 2014 4:57 am

The plump, balloony appearance of that cell is typical of a vorticellid when it has been on the slide too long. The overall size doesn't increase, though...I think your guy just happens to be a big species.

You could well be right that this spinning is an adaptive behaviour, helping the cell detach from its stalk. Certainly, the strategy of swimming away from discomfort and danger is a common one among peritrichs. For whatever reason, though, even non-sessile ciliates often spin when they're dying.

billporter1456 · Post by **billporter1456** » Wed Mar 26, 2014 9:42 am

Bruce Taylor wrote:The plump, balloony appearance of that cell is typical of a vorticellid when it has been on the slide too long. The overall size doesn't increase, though...I think your guy just happens to be a big species.

You could well be right that this spinning is an adaptive behaviour, helping the cell detach from its stalk. Certainly, the strategy of swimming away from discomfort and danger is a common one among peritrichs. For whatever reason, though, even non-sessile ciliates often spin when they're dying.

As I recall, that Vorticella hadn't been on the slide very long, but my memory has proven to be less than perfect. I find your comment about rotation being common in dying ciliates intriguing. While it seems unlikely that the reason for it will ever be known, I will definitely keep my eye pealed for it in the future. As always, I appreciate your learned comments and observations.

Protos · Post by **Protos** » Thu Mar 27, 2014 5:46 am

Bill It's always a pleasure to watch your videos with your original eye angle !