Please help ID

[MrMikeB]

Hey all,

I was sold this awhile back (sight unseen) as a Tigertail cucumber. This is obviously not the case. Since they were alive I placed them in the tank anyhow (there are 2). Since then I have been really concerned as these things are creepy and hardly EVER move. I had one of them crawl into my torch coral and stay there completely motionless for 3 weeks. I thought it was dead so I tried to remove it. It was hard as a rock and had literally glued itself to the torch. I finally pride it loose and stuck it on top of some LR just to be sure it was dead. That night I peeked in on it with a flashlight and it was standing on what could be called its tail slowly moving its 'head' around. It finally settled into the same rock and has been there ever since, again without moving.

Do you have any idea on what this could be? I cannot figure out what it eats, how it stays alive, or pretty much anything else about it save its really creepy. Thanks!

 

[saltykelly]

I'm no pro, but it looks like a nudibranch. It may have been eating the torch. Was the coral retracted or slimy or anything that might suggest it being unhealthy?

 

[Genicanthus]

It's a sea cucumber. I can't tell you what species it is. Cukes fall into one of two feeding modes: sediment feeders and filter feeders. Sediment feeders will eat detritus from sand and rock by mopping it up with their tentacles, filter feeders will extend tentacles out of their mouth (similar to a feather duster) to catch stuff in the water. You should eventually see it doing one of these, and can then feed accordingly. DON'T move it anymore! Just let it settle down on its own.

 

[MrMikeB]

It was not eating anything on the torch - no sign of slime or anything like bite marks. So do filter feeding cukes just adhere to one spot and sit there indefinitely?

 

[Genicanthus]

<a href=showthread.php?s=&postid=8923793#post8923793 target=_blank>Originally posted</a> by MrMikeB
It was not eating anything on the torch - no sign of slime or anything like bite marks. So do filter feeding cukes just adhere to one spot and sit there indefinitely?

Pretty much. Once they find a flow regime that's suitable they pretty much stay put. I've never seen this kind before, so I don't know that it's a filter feeding one. If it's moving to high points on rocks it's probably likely though. Is it extending its feeding tentacles at all? Do you have any substrate picking fish like angels, butterflies, or tangs that may be pestering it?

 

[MrMikeB]

I have Tangs and a ton of inverts (crabs, snails, stars, etc.) None seem to pay much attention to them. I have never seen anything extend from it like a feeding tentacles - hence thinking it was dead. Really bizarre, I have not seen it eat or excrete and rarely see it move. It is hard as a rock and glues itself to whatever surface it finds and will sit there for weeks on end. ???