How do the proboscises of ribbon worms work, specifically the way that numerous little branches quickly form?

Question

It’s something that’s been on my mind for a while, and I’ve literally never seen anything like it. You’ve probably seen that video from a while back of those pink marine worms wiggling around as one of them spits out a white rod that quickly develops numerous branches spreading out from the main “trunk”. As terrifying as it is, I’m also really intrigued as to how these branches form, since I was always under the assumption that it was a slow and gradual process instead of something nearly instantaneous like that. Is it stem cells rapidly multiplying or are the branches already there, just rolled up really tight when not used?

I know a Japanese anime studio is going to pick up on this phenomenon and make some pretty weird shit.

In: 1

Answer 1

Literally just Google “ribbon worm proboscis” and click on the Wikipedia article. They are folded up inside the body until it tenses muscles to fill them up with fluid. So it’s like blowing up a balloon.