Gastrovascular cavity vs. acoelomates?

Acoelomates have no body cavity.

The acoelomates have three layers without a space ("a" means without, so this is without a coelom). The coelomates have a coelom made entirely from the middle germ layer, while the pseudocoelomates have a coelom made only partially from the middle layer.



https://biology-forums.com/index.php?action=gallery;sa=view;id=14282

Taken from the link at the bottom of your post...

"The acoelomates include two phyla, Platyhelminthes and Nemertea"

Are you sure about that?  Because other websites say that cnidarians are also acoelomates.

https://www.google.com/#q=are+cnidarians+acoelomates

Yet, cnidarians do have a gastrovascular cavity apparently, according to many other websites.

https://www.google.com/#q=do+cnidarians+have+a+gastrovascular+cavity

Anyhow, I think I have found the answer I'm looking for on the following webpage:

http://bioweb.wku.edu/courses/Biol225/225lab3.html

"Platyhelminthians are acoelomate so they do not have a body cavity but they do have a digestive cavity. Do not confuse the gastrovascular cavity with a body cavity."

I appreciate that you took the time to try to help, but I don't think you understood my question and I think you provided me with some incorrect information which I quoted above.

You're welcome. Sorry I couldn't provide anything useful. Good luck on tomorrow's test.