Is this a ciliate? ID please?

[DrTheo]

Hi,

This I found is seawater in the Netherlands. I think is is a ciliate. And what is de dop/eye in the "head". A vacuole, a nucleus?
Thanks for the help.

Link to video: https://youtu.be/3LrvORj8d5o

A videoshot below

Theo

Microscope Olympus BX40 lens 10x 0,25. Camera Nikon Z6ii

[Bruce Taylor]

It is not a ciliate, but a flatworm of some kind. The round structure appears to be a gravity-sensitive organ called a "statocyst," used for orientation (they are found in marine acoelomorphs, but I'm not sure what other groups might have them). I don't know much about animals, so I can't help with identification.

[DrTheo]

Thanks Bruce.
I never heard of acoelomorphia although I read the book The ancestor's tale written by Richard Dawkins. He wrote chapter about it. I will read that again.
I'm sure you are right : this is a acoelomorphs with a statocyst. Thank you very much. I just looked at a lecture about it on YouTube.

Theo

[macnmotion]

Pond snails have statocysts