What the heck is this?

[evenkeel]

For the past couple weeks, there has been a strange worm in my tank that darts back and forth between the rocks. I wish I could get a picture of it, but it moves way too quickly, so I'll try and discribe it for all of you in hopes of finding out what it is.
It's black, and about an 1 1/2" long and 1/4" in diameter. The one time I did get a decent look at it, it appeared the the throat area had expanded (similar to a frog), then retracted to the size of the body.
It peers out between the rocks, then quickly darts under the rocks.
Any ideas?

 

[jrittz]

Did it look like a centipede at all? Bristleworms start out very small and grow to be very large. They are good for your tank when they are small and can be damaging to your tank/fish when they get large. Of course some fish eat these little guys. But as I was saying, if you can get a picture of the worm, that's really the only true way to determine what type of worm it is and if it's beneficial or detrimental to your tank/fish.
Bristleworms big or small can sting you pretty good so be careful if you're planning on grabbing it if you get the opportunity.
Jrittz

 

[bang guy]

Doesn't sound like any type of worm I've heard of. Are you sure it's not some type of Goby that hitchhiked in on a rock?

 

[evenkeel]

Thanks for the replys. Bristleworms are generally a pinkish color...and I never really thought about a goby. But like I said, I generally see it from rock to rock. I'll keep my eye on it and see if I can get a pic.

 

[evenkeel]

I got a fairly good look at this last night, so here's some additional information.
It's black and the body looks similar to a shrimp (several sets of legs). Probably because he/or she has been feasting on them for a couple weeks. And it's got (now, don't laugh) what appears to be very small...ummm, horns coming out of the top of the head. I don't think it's a Goby, as Bang Guy suggested and I still have no ideas, anybody else?
p.s. and no, I wasn't drinking before I saw this.

 

[oceanic110]

Mantis Shrimp?????????

 

[cozmo2312]

does it look like this... this guy was in my tank, i think it's a bristleworm

 

[bang guy]

I think Oceanic hit it... unfortunately.
Does it look like this critter?

 

[evenkeel]

yes, similar
I can assume from your response "unfortunately", that these are not good for my tank?

 

[bang guy]

Mantis are one of the oceans most effective hunters. They eat just about anything that moves and some that don't.