Polychaete ID needed

[ptychoptera]

These were collected last night on some algae covered rocks around Hilo, HI. I have 3 on my glass currently, all in a dark and relatively stagnant part of my tank. The only "feather duster" worms I'm familiar with are the large guys and the little spiral/straight tubed guys. So who's this little tubeless guy. Note the copepods in the first pic for size comparison.

 

[LeslieH]

That's in the genus Branchiomma. These have thin, soft silt tubes and easily abandon them to find a better home and to escape predators or a disturbance. Once they find a place they like they'll rebuild the tubes.

 

[ptychoptera]

Thanks for the ID.