Help required to identify large ciliated critter

[Bruce Williams]

Hi folks,

I am posting this video for two reasons:

(1) I have been unable to positively identify it although (annoyingly) I am certain I have seen a photo of it somewhere.

(2) The video (link at end of posting) contains a blindingly fast contraction (don't blink) so continues the theme in Tom's recent posting:

http://www.photomacrography.net/forum/v ... php?t=1126

The still photo taken from the video is rather poor so I'll try and describe it for you:

The creature is just visible to the naked eye - fully extended it was about 12 times the length of a pretty, pink Blepharisma that was present on same slide. So (very unscientifically) I would say that it is at least 1mm long. In the still shown below the head is to the right.

It was much broader than the Spirostomum in my last posting and the cilia (that totally cover its body) are orientated orthogonally rather than spiral fashion (this is more obvious in the video). Also it did not rotate while swimming.

Here's a still from the video:



Here's the link for the video:

http://brucewilliams.ifastnet.com/Divx_ ... tract.html

Bruce

[Ken Ramos]

What you have here is probably a flatworm or planaria. I just barely detect the two eyespots at the anterior. They act somewhat like Vorticella when they encounter something other than food, by contracting into a ball almost. Their bodies are covered with very fine cilia and they are very interesting to observe at high power once the slide begins to dry some and they cannot move as rapidly.

[Bruce Williams]

Hi Ken,

Thanks for your comments. I had assumed that flatworms did not have cilia so your info to the contrary makes all the difference.

To be honest, I'm not surprise - when I first saw the creature my first thought was "its a flatworm". However I had never seen one with obvious cilia before - and usually the eye spots are very evident - also the species I've observed previously all had sort of arrow shaped heads.

I observed this particular animal for quite a while at higher magnification and the beating cilia were very evident - so much so that you could see the flow of water/debris around it. I still have the water sample that produced this worm so hopefully there will be another opportunity to observe it.

Bruce

[Ken Ramos]

It may not exactly be a flatworm or planaria, there Bruce, but one quite similar . I don't know a lot about them but I have ran across them quite a number of times in water collections made from tiny slow moving creeks with lots of decaying organic matter, something of which I need to get back to doing. I have not made a collection of anything but dust in the past two or three months.