Mystery worm

[mhaze]

I feel like I should know this, but...

I've got mystery worms in my display tank. They come out at night and are photo-reactive. They are brown and very "fluffy." At first I thought maybe brittle starfish arms, but I sucked one up in a large medicine dropper and the only thing attached was a tube of glued-together aquarium gravel. They also hang out in rock work.

I am sorry the pics are extremely poor. These are pretty hard to photograph, however, since they retract almost immediately after being exposed to light. They range from about two inches to about five inches.

Very likely TBS hitchhikers.

Any ideas?

Thank you for looking!

 

[olemiss reb]

Google Oenone fulgida.

 

[mhaze]

Thanks for the response! I am a bit familiar with these nasty buggers. I understand how the photos, especially the first two, look like O. fulgida.

Native range and size are right, but these creatures do not have any (visible) eyes or mouthparts. They seem to be filter-feeders? Each one is semi-stationary, and does not move around much. They behave more like feather dusters in their locomotion and tendency to retract. They "wave" a little in the current. End of each individual is tapered at the end and covered with "fluff" that is not arranged in any pattern resembling legs. No mucous production to my knowledge.

Also I have a number of lesser bivalves (turkey wings, jewel boxes, and the like) that have been growing well with no damage. No notable damage to other mollusks either.

Honestly, they mostly resemble a smaller version of the roots of a floating freshwater plant. I'm only guessing they are worms because of the small sand casing. Maybe I can get one out and throw it under the scope...

 

[mhaze]

Diopatra spp., perhaps? They do seem to like the sand, are reactive, and nocturnal. Some of the pics of diopatra look like they have fluff. Mouths on my worms must be really tiny, though, since I have not been able to see clearly visible mouthparts. They mostly just look like fluff. Like a crinoid or brittle star arm (but clearly not one of these because there is no "body" attached). I will throw one under the scope tonight, if I can.

I have a HUGE population of pods in the tank that come out after night they could be eating if they are predatory (nutrients and algae are in check, just no pod predators in the tank). No losses with coral, fish, inverts, etc. so what are they eating if predatory?

 

[mhaze]

Okay, I got off my lazy behind and took more pics. These just confused me more, though!

First pic is just no scope. It's about one to two cms long, including the sand casing.

Second two pics (2 & 3) are from dissection scope, which doesn't have a camera, so I just have to hold up my cell phone (that's why it looks weird with the black spots).

Last two (4 & 5) are from the microscope, including one of the "mouth" end and one of the side. The camera on the microscope makes things looks a little dark.

While I had it under the scope, the little cotton-swab-looking things wiggled a bit, and the entire critter moved slowly, but wormy-like. I never saw any mouth-parts or eyes?! The whole thing inflates a lot at night!

Any ideas, anyone? Thanks for looking!

 

[TosT]

Could it be a goblet worm colony? Look up Barentsia.

 

[mhaze]

Hey now! That looks super close! We may have a winner...

Thank you thank you!

The individual I pulled did not have "cups," but did seem to have polypoidy-things. Maybe they are closed? That would explain how it could be a nocturnal animal with no clear "mouth." (Especially if me messing with it caused it to retract a great deal.)

Interestingly, I have not encountered these before! Are they filter-feeders?

So are they okay, or should I pull them?

 

[TosT]

They could be retracted. It's interesting that they react to the light. You could try tricking them by leaving them under the scope in the dark for a bit. If you have access to chemicals, magnesium chloride will "relax" certain kinds of inverts, making them open up. If it's indeed goblet worms they're just filter feeders and harmless. Neat find.

 

[mhaze]

Ooh! I will check and see if I have some magnesium chloride in ye olde chemical closet!

I could probably put them in the dark under the dissection scope some evening and see what we could find...

I really think this is along the lines of what it is - an entoproct and all!

Thank you very much!