What in the world?

[Ironcat]

At first I thought it was some sort of bristle worm but can't ID it for the life of me.

It's about 5-6 inches long.
It was free swimming off of Boynton Beach in about 2 feet of water.
The little yellow "legs / fins / brsitles" move in a feathery motion while the "worm" itself swims in a very serpentine motion.
I have placed it in a plastic container and it "swims" with the pointy-tail end going first and the rest following behind.
it occasionally flips itself and the "underside" is a little bit lighter brown color.
I tried offering it a piece of driftwood and a mangrove pen butit had no desire to cling to anything.

 

[LeslieH]

It most certainly is a polychaete, AKA bristle worm (polychaete is a latin term that means many bristles). If you can take close up shots of the head & body parts I can give you more information on what kind it is.

 

[Ironcat]

Hi Leslie;
I had assumed he was 'some sort' of bristle worm but was looking for more of a distinct description and identification... oooh, maybe I found a new one!

Unfortunately that is as good a picture as my camera can take.
I've gotten right up on his "face" to get a better look but can't see anything...
No mandibles, no mouth opening, no eyes, nothing, it's just smooth and rounded.
I'm sure everything is there but I can't find it.

I also figured out how they get into teensy little rocks, I watched him take about 30 minutes to squeeze his way through one of the holes in a mesh net box.

 

[300bar]

I'm pretty sure it's a ragworm.
Ragworm or Nereis Diversicolor