Spirostomum video illustrating longitudinal rotation

Bruce Williams · Post by **Bruce Williams** » Sat Dec 02, 2006 2:46 pm

Hi folks,

Tom's video of Spirostomum (or Metopus) made me kick myself for NOT thinking to photograph or video the animal in its contracted state. I watched it for at least an hour, took maybe 50 pics and 3 short videos - but nothing at all in its contracted state. I guess that's one of the benefits of a forum like ours - we are inspired by the thoughts and actions of others.

Anyway here is a short video of the same Spirostomum. It illustrates the longitudinal rotation evident as the animal swims forwards and backwards. You may need to watch it a couple of times in order to make out the rotation. In particular watch the head and the spiral myonemes (thanks Ken) around the transparent contractile vacuole. I apolgise for the strobing but hopefully it shouldn't detract too much.

http://brucewilliams.ifastnet.com/Divx_files/spiro.html

Bruce

rjlittlefield · Post by **rjlittlefield** » Sat Dec 02, 2006 3:24 pm

This looks great -- no trouble at all to make out the rotation.

What fascinated me was what I take to be emptying the contractile vacuole. Between 16 and 18 seconds into the clip, the whole end of the critter looks like it sort of deflates and becomes a twisted flat ribbon instead of an inflated cylinder. I guess this makes sense if the outer membrane is fixed size instead of stretchy, but I surely was not expecting it.

Neat!

--Rik

Bruce Williams · Post by **Bruce Williams** » Thu Dec 07, 2006 7:10 pm

Thanks Rik,

Yes the strange twisting/flattening action happened several times over the period I was observing the creature. Your interpretation would seem to make sense, particularly considering that it's a singular and proportionally large contractile vacuole.

Bruce