Help ID living pipecleaner

[LukFox]

I've been seeing what I thought was just dying caulerpa leaves, but it puzzled me because the macro has been doing quite well except for these white leaves. Often I didn't see the white leaves so they were easy to ignore, and I thought they were rotting off.

Well when I turned on the lights today and admired my red macro, I saw the "dying caulerpa" move on its own without the aid of the current?! I looked closer and there were 10-15 "pipecleaner" type things moving all around, and then recoiling from the light. They are white and have spaced feeling hairs with bulbs on the end of the hairs. I think they all belong to the same animal that must be living deep in the macro, but I suppose they could be individual...

I turned the lights off for an hour, and when I turned them on I was ready with the camera. I got them in action. They kind of wave around, too.

The biggest one:

recoiling

Smaller ones further back:

So what are these things?? This is pretty exciting. It's been a while since I've seen something weird! They don't seem to be harming anything, by the way.

 

[Bongo Shrimp]

Those are digitate hydroids. I've had them come in spurts and they never seemed to do too much harm. I have heard though that they can be devastating sometimes, stinging corals and what not.

 

[LukFox]

Ohh thank you so much! I don't have any corals, so that's not a problem. They don't seem to bother my macro or fish so it's all good . How cool!

 

[mndfreeze]

Def digitate hydroids. I had some kill a bunch of zooa's. had to throw away the entire frag/colony to make sure they didn't spread.

And they stung me. doh!

 

[LukFox]

Sorry to hear about your zoas! How bad was the sting? Is it something I should worry about if a fish was to bump into one at night?

 

[Bongo Shrimp]

No, i have picked them up with my fingers and never had a problem. Fish will be fine too. Don't worry about them. They usually just bother corals.

 

[mndfreeze]

ONly my zooa's got hit by em. No fish or inverts that I know of.

They left little red irritation marks on the tips of my fingers, nothing drastic to me or anything, enough to notice though.

 

[LukFox]

Okay, I was just worried that if I get a dwarf eel or pair down the road, if they might have a problem with them. Living in the rocks and all, you know... I'll wait and see I guess.

 

[mscarpena]

I have a few in my tank and they dont seem to bother anything. They are close to my corals and I have plucked them off with my fingers-No issues.