XL Bristle Worms and something Green??

Question
QUESTION: Hi, I have been noticing several 9-11 bristle worms in my tank (which i have crabs, fish, coral and anemone in)these are all about 6inch in length except one which unlike the others (being white / red and grey line down body) is flat, wide and about 10inch (to what i've seen of him) and all grey (could you tell me what this is please), also i have a long thing which is green, looks like a piece of string, it is really thin and round but really long???also only comes out at night (i have been trying to get a pic for you) I have tried the trick with the tights over the pipe and fish inside, and piercing holes in a tub, neither have worked, do you have any advice pleas? I had an arrow crab, but this seems to have been killed - not sure what by but it started by legs going missing. Thanks

ANSWER: Hey Amanda,
Without pictures its really hard to id anything accurately. There are lots of Polychaetes that grow large, and 100's that are predators and eat other scavengers. The family Eunicidae and the family Lysaretidae contain large worms that are commonly found in aquaria. The first of these groups, the eunicid worms, is a huge and diverse group with over 200 species. The second, the lysaretid worms, is a small group with only about ten or fifteen described species; unfortunately, the lysaretid worms are ALL predatory and deadly to many reef aquarium inhabitants(mainly your clean up crew, crabs, snails etc). Even more unfortunately, they are extremely common in live rock. The one that appears to be all grey is most likely Hermodice Carunculata, The Carribean Fireworm. It appears to be a solid grey and gets its name from the sting it delivers not the coloration. The green fellow, really depends on whether he appears to be smooth or has the "centipede" look to him. If he's smooth he probably a beneficial, scavenger, tube worm that will harm nothing.
My best advice is a piece of pvc pipe, drill small holes all over it, stuff a nylon stocking inside with a few pieces of krill or fish inside it, and cap both ends. Sink it in your aquarium at night, get up in the morning and check it and dump it. You may have to do this nightly for a while but it has worked for me for years. Wish I could give you an immediate fix, but the only predators of large worms are worse than the worms usually(large species hermits) and will destroy and eat anything they can get ahold of. Keep trying the trap. Let me know how it goes or if you can get a picture. Good luck.

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QUESTION: thanks Glenn,

I'm going to try the pipe tonight, the grey one looks just like the one you said is a Caribbean fireworm, are these harmful to the tank? and the green one seems centipede like but it is like a piece of green string with tiny legs either side, it looks nothing lie the bristle worms.
Thanks

ANSWER: Hi Amanda,
Carribean Fireworms can be pretty devastating to corals and small inverts(hermits,crabs,snails), but thats a "Can Be", if you can trap and remove them it is best to. The green guy, as I said, is probably beneficial, just watch him and see. Good luck with the trapping and let me know how it goes!

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QUESTION: Hi,

Just to let you know - didn't catch a thing last night....saw them all and they were all over but they were not one bit bothered about it. I was thinking about a banded shrimp or something like that? what would you recommend?
Thanks

Answer
Hi Amanda,
The banded shrimp work well... with small specimens. If you can find a few large enough banded shrimp they might work... or they may become food for the unwanted worm. I would keep trying the pipe nightly for a couple of weeks. Six Line and Lunare (or Moon) Wrasse are notoriously good a finding and eating these pests too. But I would only resort to a new addition if you have the room and the community that they can thrive in. Let me know how it goes and I'll do a bit of research and see if I cant figure a new trick for you to try.