Sorry OP for the thread-jacking that's going on.
motorcyclegrin said:
I got to swim in a pond FULL of jellyfish (with no sting!) in Palau. Great diving!
Sounds like Jellyfish Lake (creative name, eh?). I did that too. Here's a photo from that 'dive' (we were free-diving, not scuba diving). Sorry for the lower-res, it's actually a still-frame from the video (video's not online right now):
Now this is a *real* jellyfish. This is me looking at an egg yolk jelly:
I had one dive where I had to swim through a field of jellies as thick as the one in jellyfish lake, but they were brown jellies, which *do* sting. For the most part I was OK because the only exposed skin I had was my face. But at one point it was clear that one was going to hit my face, so I put my hand over my face to protect it. What I didn't realize was that I scooped one up in my hand as I brought it up to my face and thus took one and smashed it right into my face. Ouch!
twitchmonitor said:
Is that a mouth on those things?
Insomuch as you might say that a salp has a mouth, then yes I guess you can say it's a mouth.
The open/close and contraction pushes water through their bodies, which provides both propulsion and it's how they get the plankton in them to eat. They're actually a pretty interesting species because they're often studied as the 'starting point' for where vertebrates evolved from since they have preliminary vertebrate forms and one of the first instances of a nervous system.