Newbie needs help identifying a creature

[Itchy]

We've had our 110G tank for about 2 months now and all is going well. We've only lost one fish (a scooter) and we suspect a crab may have gotten him. Tonight, we had some neighbors over and were showing them our new tank and while feeding 2 cubes of frozen brine, I noticed a large tentacle coming out of one of my pieces of live rock. It was about 1/4"-3/8" wide and looked kind of like a centipede. Then I saw a smaller tentacle come out...this one about 1/8' wide and a more reddish color. Both arms were moving towards a piece of brine that had come to rest in front of their holes in the live rock. I did not get to snap a picture...I was too amazed at the life I didn't know I had bought! After the food had been claimed by the larger arm, they both went back into the rock and I haven't seen them since. I may not see them again for a couple of days until I feed again. Can anyone make a guess at what these may be? If I can get some ideas, I can search the web and see if I can match a photo to what I've seen. Thanks in advance!

[Pineapple House]

First off, welcome to the boards Itchy!

Well...it's a spaghetti worm
http://krupp.wcc.hawaii.edu/BIOL200/powerpnt/trophic/img065.jpg

These strands/tentacles you describe are the feeding tentacles. The worm sends out feeding tentacles which constantly search the ocean floor for just about anything dead, dying or deposited there, along with fish food. They are harmless, and pose no threat to your tank. Quite interesting to watch if you ask me :-)

PH =)

[Itchy]

Thanks for the welcome, PH. Actually, after doing some reading of other posts here, I'm beginning to wonder if these aren't Bristle Worms. Looking at the pic you posted, that doesn't look like what I saw. This was a single "arm" coming out of a hole in the rock rather than many smaller tentacles. What do you think? If I can find some red cellophane to put over a flashlight, I'll try to look later tonight. Time to raid the kids' rooms! :)

[Pineapple House]

Sometimes these worms will only put out a single tentacle for feeding.

Also, some brittle stars, usually the size of 12mm, will hide in small holes in rocks, and will stick out a tentacle or so for feeding.

Just some more ideas.

PH =)

[phistio]

yeah...based on the description, i would have guessed bristleworm...this it ?

http://www.reeflounge.com/forum/download.php?id=130

[Itchy]

yeah...based on the description, i would have guessed bristleworm...this it ?

http://www.reeflounge.com/forum/download.php?id=130

That looks much more like what we saw. I think we have at least 2 of them. Now the question is...are they bad and should I get rid of them? I've read about people constructing traps for unwanted or undesirable critters.

[phistio]

while in the past bristleworms, and fireworms we're thought to be pests...they are getting a better rap...

first off, i think people thought they were pests because of the stinging sensation one gets when they touch them...ome of these worms are potentially quite toxic, and as such, if you discover a polychaete in your tank that looks like a "wooly-bear" caterpillar (like the Hermodice carunculata pictured here), please don't touch it with your bare hands!http://www.aquarium.net/0697/images/pic1.jpg

well, after that dire warning, i have to reiterate that the vast majority of polychaete species are at worst harmless to a reef tank, and at best beneficial in maintaining a healthy environment.

to get back on topic, you've just discovered a polychaete in your tank and you're concerned -- what is my advice? ff they are not causing any damage, and are not very large or in high densities, you probably should not worry.