What are these?

[little fishes]

I just got a 4" unknown acro colony. It has three acro, crabs, two brittle stars, and some very small filter feeders of some sort that I have not seen before. I will not be able to get a picture as they are too small, so allow me to describe them as best I can. They are living within the acro itself, without looking to closely you might think there was just another polyp there. Upon close inspection they are obviously some small filter feeder hosting in the acro and not a polyp. There is a single fan about 3-4mm across and 2-3 mm tall. It is light colored/clear. It has 12 parts to the single fan, each much finer then a human hair and faned out in a clam shell shape. The 12 parts seem to connect in pairs right before connecting together such that there are six pairs connecting to the part that "hides" it the acro. They are open most of the time but "blink" inward on average every few seconds. When they do this the fan folds in quickly like a closing fist and then quickly re-opens. It appears that it is actively feeding. I know of several things that host in porities; x-mas tree worms, and filter feeding shrimp(or were they crabs?). This is not any of those.
SO I am hopeing someone will know:
1. What these are
2. If it is taking over the coralites or simply hosting in the conostrum of the acro
3. If it is somthing that will become a problem (it is currently in a Q-tank and I want to know if these things are "safe") I think they are kind of neat so long as they are not harmful!

Any input (or suggestions of people to contact) would be greatly appreciatted.

Cheers,
Tracy

 

[little fishes]

OK- so I guess they are Barnicles. anyone know how they get into the acro? Do they burrow through the fleash to attach to the skeleton?

 

[NaH2O]

I think it bores into the coral, or perhaps the coral grows around it?? I found this really cool video of barnacles feeding: Barnacle Feeding. Here is some more information on them: Barnacles. Regardless, may people have these as hitchhikers, and don't see any problems with them. Enjoy them as part of your tank's diversity

 

[LeslieH]

Take a look here for some images of coral barnacles:
http://www.poppe-images.com/images/search_results.php?category=barnacles&family=PYRGOMATIDAE#fs

they're fairly common. The barnacles settle on the coral & then the coral grows around it. Basically harmless although they might compete a bit with the coral for food.

 

[NaH2O]

Welcome to Reef Frontiers!!! I've always enjoyed your worm identification posts over at RC. Thanks for the info on the barnacles. I wasn't sure if they bored into the coral or not (read that one time on another forum), but it made more sense to me that the coral grew around it. I just wasn't sure.