Critter ID please

[Mdoug25]

Hoping I could get an ID on this guy. I was feeding DT's Phytoplankton and this creature happened to be in the water column nearby. Apparently it was interested in the food source because it began to wig out, which is what caught my attention.

 

[Sk8r]

Hesionidae, by the short body, but I'm not sure re bristles v legs, and I find absolutely no info on behavior.
Try http://saltcorner.com/sections/zoo/inverts

 

[LeslieH]

WAs it vibrating rapidly as it swam?

 

[Mdoug25]

I observed 3 distinct behaviors. The first, and the one that caught my attention was a twirlling-spinning-corkscrew like movement. This seem to propel it forward. The second was that it competely froze and began to drift in the currents of the tank, back and forth etc. Finally, at one point landed on the glass and made worm like movements, only to release from the glass and beginning the twirling cork-screw movements again.

 

[Mdoug25]

Still no id on this one...

 

[LeslieH]

Thanks for the comments on it's behavior. That tells me it's the epitoke of a syllid polychaete worm on a spawning swim. At some point it would have burst open releasing the eggs or sperm it was carrying. Unless you have both males & females you don't have to worry about a population explosion.

 

[Mdoug25]

Thanks for the response LeslieH.

Actually, I do have a rather large population of small worms throughout the tank. They currently inhabit the sandbed building tubes from the substrate, as well as borrowed into the live rock. Is this something I should be concerned about?

Would you review some pictures of these worms for me?

-MDoug

 

[LeslieH]

Probably not. I can't be sure without actually seeing the worms but if they're small worms in the sediment they're either eating detritus or other small organisms. I'd be happy to look at images. You can either post them here or send them to me via PM. Just have the worms fully submerged in water so all the appendages can be seen clearly.