Mushroom or Elephant

[Ahwagirl]

So I picked up two mushrooms at the LFS yesterday. One is definitely a mushroom. I've had them before.

The other (a pair) didn't look quite the same, but the rock they are on is gorgeous with ton of corraline so I bought it. It's been a while since I read up on mushrooms so I pulled out my invert books. Of course, that's when I read about elephant corals and how they eat fish. Now these two (that don't look like the smooth-surfaced single frag I bought), are still small (about 2 inch across) but as I mentioned look different from the other single guy. They are green with spots sort of. I figured I'd wait and see if they grew (having read that elephants get huge) and if it did, I'd get rid of them then.... take back to LFS.

Well, today (just brought them home yesterday) my pencil urchin is over on the rock (lots of yummy corraline, I'm sure) and one of her pencils gets in the green/spotty "mushroom." The next thing I know it's curled up and rather gooey looking. Her pencil seemed stuck in glue-like substance. I couldn't tell if she was attacking it and the polyp was protecting itself or if it was trying to attack the pencil. So I moved her.

Here is a pic. The disc in the background is how they normally look.... the one in the foreground is the gooey look a minute or so after the "attack" (but now it's back to normal).

So.... are these elephants? If so, should I get them out of my nano NOW before they munch my clown fish? Or do some variations of mushrooms react this way when touched by another critter, but are harmless.

Help!!

TIA!
Jill in Phx

 

[Ahwagirl]

follow-up... sorry I didn't post the proper names. Talking about the difference between a discosoma/actinodiscus vs. amplexidiscus fenestrafer.... I'm worried about the safety of my clown fish....

Thoughts anyone?

 

[Apercula]

The picture does not look like Amplexidiscus, I would guess its probably a Rhodactus sp. mushroom. Amplexidiscus has a very distinct band around the outer rim.

Large brown Amplexidiscus, you can see the band Im refering to about an inch in from the rim. The green mushrooms above and to the right are Rhodactus, but probably not the same species as yours as they seem less hairy/bubbly than yours.

 

[Ahwagirl]

Ours "kind of" has a band.....

Here is what I was told on another site:

"Large species of Rhodactis can trap fishes, in the same manner as the related genus Amplexidiscus"

http://www.advancedaquarist.com/issues/oct2002/invert.htm

So if it's not an elephant, but if it's a Rhodactis what is considered large and fish eating?? :fish1:

 

[Ahwagirl]

Here is exactly what the ooze looked like.

http://upload.wikimedia.org/wikipedia/commons/a/a1/Rhodactis_cf._inchoata.JPG

 

[The Escaped Ape]

They're mesenterial filaments (the coral's guts). Often ejected when the coral is under stress.

 

[mr chris]

I had one and it will eat fish especialy sick ones ,I lost a damsel to the giant mushroom (no great loss and sure looked nice after though)Not sure of the name though

 

[Reefmonster]

I had a tank dedicate to all types of coralimorphs that was full of damsels and never 'lost' a healthy fish, but like everything fish die, so just because they will injest a dead fish does not mean they will trap a healthy fish...I timed the closing when I fed mysids to the aquarium and it takes about 15 minutes to close, and about 30 to extrude their messenteric filaments. Any fish that gets caught after that time is better off dead, IMO. I really don't think you have anything to fear. You should be more worried about a mantis shrimp that may have hitched a ride on your rock.

BTW...The filaments also come out when they are feeding, not only when they are stressed.