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Indentify this sea slug?


Railstone

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Placed a new Zoa frag in my tank and felt something kinda soft on the side but coved in shells. Didnt think much of it thought it might be a sponge till this thing began dropping off the rock and extened a breathing tube! Its got a kinda rocky texture to the skin i can see and is marked by a dark brown and white X. It has sort of bristles with balls on the end sticking off it and has a number of shells glued to it. See 2nd pic for circle of breather.

 

 

 

 

 

 

*Edit* cant host pictures ill try again later :(

 

 

 

 

 

 

 

 

 

 

 

 

 

 

f_DSC02262m_60fab19.jpg

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Thanks for the reply and help with the pic links :). It has since jammed itself under the zoa frag and i cant get a better shot of it. I hope its not a cucumber i dont want it to die and nuke my tank! Any help is welcome!

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Dunno seems kinda long for a sea urchin but i dont know alot about them. Do they often stick shells and other stuff to there backs? The thing is currently lodged in a narrow crevice in my LR.

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Ok i am almost sure its a kind of sea cucumber. As Diane suggested i watched it at night after i increased the water flow near its hiding space and sure enought a set of about 8 branching feeders where extened out from under the rock. Got some pics ill post tommorow of them fully extended. Do cucumbers pose as much of a threat as i have heard about nuking your tank?!?! Also i cant find anything about them collecting shells on there skin either??

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Ok i am almost sure its a kind of sea cucumber. As Diane suggested i watched it at night after i increased the water flow near its hiding space and sure enought a set of about 8 branching feeders where extened out from under the rock. Got some pics ill post tommorow of them fully extended. Do cucumbers pose as much of a threat as i have heard about nuking your tank?!?! Also i cant find anything about them collecting shells on there skin either??

 

Those branching tentacles would seem to nail it. Like you, I couldn't find anything about cukes collecting shells, etc. Of course, their close relatives, the urchins, are known to do this. But then they have spines...

 

I assume you ran across pages like this in your search?:

 

http://www.wetwebmedia.com/seacukes.htm

 

I was hoping to find a sea cuke site/forum like the great one that exists for sea slugs, but didn't run across one...

 

Looking forward to your pics! :)

 

--Diane

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Such a fascinating creature! It's a bit maddening to not find more info online...FWIW, here's what Ron Shimek has to say about cukes in general in his "Marine Invertebrates:"

 

"Repulsive to many, fascinating to anyone with a bent for biology and, once in a while, simply beautiful, sea cucumbers are for marine aquarists who love the unusual or even bizarre.

 

"As a start, these are animals that may, in a defensive reaction, or in response to severe stress, expel part of their internal organs (viscera) through the anus. The ejected viscera are sloughed, and if the animal had been in prior good health and the eviscerating stress is removed, the animal will grow a new set of internal organs. If this happens in a well-aerated or well-skimmed aquarium, and the eviscerated guts are removed from the tank, generally nothing drastic will occur. On the other hand, if the eviscerating cucumber is of the wrong species, some of the animals may be poisoned and die.

 

"Some tropical bottom-feeding sea cucumber species have defensive structures, called Cuvierian tubules or Cuvierian organs. If these animals are stressed, they may expel these tubules from the anus during a partial evisceration. The Cuvierian tubules are sticky and, in some species, contain a vertebrate-specific toxin called holothurin. In nature, this reaction probably just distracts, irritates, and sickens a potential predator. It is unlikely that it would be lethal. However, the predator is probably deterred from that particular cucumber, which will live to regenerate its lost parts. In the enclosed volume of an aquarium, however, the evisceration response, followed by the holothurin liberation, may result in contamination that could rapidly kill all the fishes and perhaps some of the invertebrates.

 

"A few other holothuroids, particularly the sea apple (Pseudocolochirus axiologus) commonly sold to aquarists, have high concentrations of holothruin in their tissues. If stressed, they tend to release this substance into the tank water, and it may be as fatal as the evisceration of the Cuvierian tubules.

 

"All of this aside, some species of sea cucumbers will perform quiet scavenging services, burrowing in the substrate of the aquarium and keeping deep sand beds healthy. Chosen wisely, a sea cucumber can be a positive addition to the aquarium. An unwise choice, however, may be a time bomb that can cause a lot of problems." (pp 405-406)

 

 

I know you are already aware of most of that info, but I copied it all because of the way it implies that SOME species may be workable in aquaria. Unfortunately, this section is followed by only 3 species profiles, none of which look anything like yours. Nevertheless, you may be interested in these bits of information he includes with their descriptions:

 

Of Holothuria thomasi, the "Tiger tail" cuke, and H. edulis, the "black sand-mopping" cuke, he says: "It may release the toxin holothurin if bothered by hermit crabs, which should be removed." And also, "May periodically shed a cuticular layer that covers the body. May reproduce asexually by fission: during this period of fission, the animal becomes reclusive for a week or two, only to emerge as two individuals."

 

He also says of both of these: "Herbivore. Ingests sediments and eats diatoms, other microalgae and bacteria. A deep sand bed is necessary for good health."

 

Of sea apples (Pseudocolochirus spp) he says: "Suspension feeders; need lots of fine particulate foods. Phytoplankton supplementation or rotifers are necessary...Slowly starves in most systems and should not be purchased unless the aquarist can feed it properly."

 

All 3 of the ones he talks about get fairly large--6" to 6 feet! I wonder if there aren't smaller species that are more likely to be hitchhikers, and maybe hardier? Perhaps it's time for you to post this critter on one of the other forum sites where there are invert specialists...

 

Nice pics!

 

--Diane

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