What is this thing??

[wraithy]

I found it crawling on the back wall. I caught in a net and some of the arms broke off it and are wriggling in the net. Is this a bad animal or a good animal?? It's freaky looking.

 

[Anonymous]

It appears to be a nudibranch of the family Phyllididae, a specialized sponge predator.
Where is your rock from ?

Regards,
David Mohr

 

[wraithy]

The rock came from a LFS in PA Called "That Fish Place". This thing is weird looking.

 

[wraithy]

Here is the answer from a reffcentral post:

It's an aeolid nudibranch, all of which feed on cnidarians. This guy is probably Phyllodesmium briareum, which feeds on green star polyps. Whether it's good or not depends on who you ask (I love them personally, and I've actually been trying to find one). If you like GSP then it's not good. If your tank is being overrun by GSP then this is a good guy. I'm sure someone in the selling forum will want it if you advertise it as a "GSP eating nudibranch."

The "arms" are called cerata and they act as gills and contain branches of the digestive sytem. They are also tipped with little sacs full of live nematocysts stolen from their food. It's fairly common for aeolids to drop their cerata if you harass them.

 

[Anonymous]

I stand corrected it is a member of the family Facelinidae, Phyllodesmium spp. a specialized soft coral predator possibly Xenia sp. but without its preferred prey it will starve in your tank.

Regards,
David Mohr

 

[garagebrian]

I stand corrected it is a member of the family Facelinidae, Phyllodesmium spp. a specialized soft coral predator possibly Xenia sp. but without its preferred prey it will starve in your tank.

Regards,
David Mohr

They also tend to starve very quickly, so if you want to try to save it you need to identify its food and feed it ASAP...in a QT tank or bucket of course

I have some Spurilla neapolitana that I'm feeding anemones. I was told they would starve in 1-2 weeks if no food was offered.

Here is a cool pic of one feeding:

BTW...these were hitchhikers from Florida TBS rock.

B.

Brian