Hello Forum,
The rotifer Cupelopagis vorax is an ambush predator. Cupelopagis is distinguished by its large infundibulum or funnel, which it uses to capture its prey (Fig 1). The muscle fibers which open and close the infundibulum can be seen. I was fortunate to observe several individuals on floating coverslips that I had prepared. These rotifers are known to settle on the underside of floating leaves. Michael Plewka has an excellent (and a little scary) side view of Cupelopagis (https://www.plingfactory.de/Science/Atlas/KennkartenTiere/Rotifers/01RotEng/source/Cupelopagis%20vorax.html). Cupelopagis is attached via a stalk on which in can turn in the direction of its prey. The stalk is shown in Fig 2, as seen from the dorsal surface (arrow). When a prey organism enters the infundibulum, the infundibulum closes around the prey like the drawstring on a sack, the prey are ingested and are lacerated by the uncinate trophi. Cupelopagis is a voracious feeder, as shown in Fig 3, in which it has ingested four ostracods.
I am also including two videos of Cupelopagis contracting and opening its infundibulum. The first one, in phase contrast, was taken using a 10X objective because the rotifer was too big to fit entirely within the sensor of my camera. The second video in DIC with a 16X objective was of a smaller Cupelopagis.
https://www.youtube.com/watch?v=TKwjyKzCz0M
https://www.youtube.com/watch?v=nrI0UKiwu8g
Best regards,
Tim
Dear Tim,
An excellent find - apparently this rotifer is extremely rare. I have never come across it, and I have been collecting rotifer samples for close to 25 years now. You say you found the specimens on floating coverslips. Where did the sample come from originally?
Thanks a lot and best wishes
Ole
Hi Ole,
Thank you for your comments. I was indeed lucky to find this rotifer. The sample was collected from a well-established pond that has yielded many interesting organisms. When I set up the petri dish for the floating coverslips, I added several leaves that were in the sample (as Martin Kreutz suggests on his website). I was particularly interested in those leaves that had a "furry" appearance, since I hoped they would have many peritrichs, suctorians and the rotifer Collotheca (I have collected Collotheca many times from this pond). The Cupelopagis appeared after a few days, and their number increased over time (I kept returning the coverslips back to the petri dish after examining them). I am planning to go back to this pond and do some more collecting and hope I get lucky again!
Best wishes,
Tim