These have me stumped.

[Anonymous]

I have some creatures on a GSP rock that I've never seen before. There are about 15-20 of them. They have a "tentacle" that they extend and retract in jerky movements about 1-1.5" long. This is not a mucus strand like some worms and vermetid snails use, and it is not a brittle star arm. It has a definite structure to it, that I've attempted to draw below. The "tentacle" is about the thickness and color of spider silk.

Unfortunately I cannot get a picture of these things. It's like trying to take a picture of spider silk in midair. I also can't see what they look like on the rock, because they are located deep in between the GSPs.

My first guess was some type of sessile ctenophore, but the tentacle structure doesn't look right.

 

[keethrax]

I have some creatures on a GSP rock that I've never seen before. There are about 15-20 of them. They have a "tentacle" that they extend and retract in jerky movements about 1-1.5" long. This is not a mucus strand like some worms and vermetid snails use, and it is not a brittle star arm. It has a definite structure to it, that I've attempted to draw below. The "tentacle" is about the thickness and color of spider silk.

Unfortunately I cannot get a picture of these things. It's like trying to take a picture of spider silk in midair. I also can't see what they look like on the rock, because they are located deep in between the GSPs.

My first guess was some type of sessile ctenophore, but the tentacle structure doesn't look right.

GSP?

 

[Anonymous]

Ah, sorry. Green Star Polyps, Pachyclavularia sp. I think these are unrelated to the polyps, but I only see them on this rock in my tank.

 

[iphy]

Love the picture.

Actually, I have a number of tube worm type animals that look like little ladders, similar to your picture. They are harmless filter feeders. I think I've got a picture somewhere, I'll post it if I can find it.

 

[Anonymous]

Those sound like sessile ctenophores. They have tentacles that are shaped like a half ladder. The ones I have are definitely different, but they may just belong to a different type of ctenophore.

 

[iphy]

Hrm. Ok, here's a picture of the worms I mean.



[/img]

 

[Anonymous]

You're not giving us much to go on here.
Do these critters have a single tentacle or palp?
If so, I'd say some type of sedentary polychaete.
If they have multipe tentacles or palps they still could be a sedentary polychaete or they may also be an errant polychaete.
If the drawing of the tentacle is halfway accurate it does narrow it down to just a few Families. 8O
Without more to go on though, I wouldn't even venture a guess on genus or species.


Regards,
David Mohr

 

[Anonymous]

I didn't see the picture iphy posted earlier--it is exactly what I have, whatever it is. It appears that it releases the same "tentacle", and only one, over and over.

I'm sure they are harmless, just curious what they are and if there's some type of obligate relationship with GSPs.

 

[John_Brandt]

Ah, sorry. Green Star Polyps, Pachyclavularia sp.

Did you know that those are now Briareum sp.? I think the Pachyclavularia genus is now retired.

I've seen the animal in question before too. I wonder if it's a filter-feeding appendage of something.

 

[Anonymous]

whatever they are, they aren't limited to occuring on gsp's

i've had them attached to lr, glass, etc

i'm fairly certain they're benign, whatever they are

 

[iphy]

Matt_Wandell said:
I didn't see the picture iphy posted earlier--it is exactly what I have, whatever it is.

Heh. Show's how good your drawng was. Seriously, I looked at your picture and said to myself, I know exactly what he's talking about.

Vitz is right, too: I've got them all over my tank. In some maiden's hair, out of liverock, even out of my livesand -- but only in places where I've got larger gravelly bits so it might qualify as liverock. Basically, they seem to be propogating at about the same speed as the little white fan tube worms. It's never more than one tentacle (or whatever it is) from one place, and I've had them for 4 years or so and have no evidence that they are not entirely benign filter feeders.

Oh, I am pretty sure I saw a drawing of them in an appendix in Sprung and Delbeeck's The Reef Aquarium, Volume One, but I've lent my copy to a friend so I can't check.

 

[Anonymous]

Are these things lightning fast? I have something popping out of a hole in my LR that is very fast...it grabs a piece of food and *poof*.

Funny you post this now...I've had this piece of LR for years and only noticed it in the past week.

 

[Anonymous]

I'm sure they're entirely benign as well, just very curious what they are. There are other rocks in this tank that came from the same location (a 10 year old tank), yet don't have these guys on them. Strange. Or maybe I just haven't noticed them yet...

Thanks for the help so far guys.

 

[Cruiznblue]

Looks like harmless filter feeder worms to me. Got a bunch in my tank.

 

[Paradoxed]

I have seen a number of these on my Chaetomorpha in my fuge. no where else tho

 

[Anonymous]

http://www.rshimek.com/odd_critters.htm#Scyphozoan Jellyfish

Shimek has a picture similar to the one posted my iphy, and the caption says it's a digitate hydroid. The discription is about 2/3 the way down the page.

 

[Anonymous]

That's them!

" These hydroids are definitely aggressive and are quite capable of "burning" or stinging other aquarium animals."

Interesting, the GSPs don't seem to mind them.

Thanks Jen!

 

[HClH2OFish]

That's them!

" These hydroids are definitely aggressive and are quite capable of "burning" or stinging other aquarium animals."
quote]

I had some of these on the glass in my 10gal jelly tank....could see em occasionally capture a pod. Nifty critters.