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Feather fishing line?

Ars Reefia

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So this thing showed up almost immediately when I started to cure my LR.




At first I thought it was some dead clinging piece of debris, but now I can make it react when I poke near it. There is a tiny purple lump on a branch of the LR that releases two long faint white lines. It can move them to some degree and can completely retract and extend them within 2 seconds. Each filament line has evenly spaced branches like a long ghostly feather




It's been hard to get something this transparent in a picture. The lines literally reach out over 10-12 inches and can brush against almost anything within half the tank. I'm worried about whether this is something that needs to be removed before it replicates or hurts anything.


Anyone know what this is?

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While they may be "harmless" they might also touch your corals often and ### them off, causing them to stay partially withdrawn or maybe fully withdrawn all day.

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While I've never seen this animal personally, your description immediately reminded me of the picture and description of Ctenophores in my Sprung & Delbeek (The Reef Aquarium, Vol. 2).


Here's what they say about them:


"Often aquarists notice what appear to be long feather-like "hairs" floating in the aquarium. The "hairs" appear to retract and elongate sporadically. They collapse into a tangled ball and then unfurl into perfect order in mere seconds. These belong to the platyctene comb-jellyfish genus Coeloplana. These odd, flattened jellyfish resemble flatworms to the untrained eye. Some species are mottled in colour while others are almost transparent. Some species live attached to the bottom or on algae, while others live in association with soft corals and sea stars. The pictured Coeloplana is the one most often encountered by aquarists and it is often imported along with Sarcophyton spp."


If you can find a copy of this book at an lfs, the picture is on page 434. It looks like two long filamentous feathers. Otherwise you might try searching for ctenophores (or Coeloplana) online...





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You rock Diane!



Coeloplana is exactly what it is, I searched the name and came up with this image which is right on the nose.




The thing is also called a purse jelly. So my question still remains . . . Do I take this thing out? Is it going to cause trouble? Should I feed it and count myself lucky that my LR has given me this wondeful gift? I haven't been able to find much help on that point yet.

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I searched and cant find anything that says you should take them out. I like to leave things in until I find out for sure that they are bad.

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I've read a post now that says that they are harmless but that they can become annoying when they grow in abundance, and I saw an article online that says they can self fertilize.


It's interesting now and I'm sure it's doing some precleaning why my tank cyles, but I'm worried about what an "abundance" of these guys is go to be like when I have MANY sets of 12 inch tentancles swaying around in a 12 gallon NC. I think I may enjoy him for a couple days but take him out before long.

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Ars Reefia,


Glad I was able to point you in the right direction. Wow, that image you found was beautiful! What a fascinating creature!


It's funny that Sprung & Delbeek say nothing about the relative plusses or minuses of this animal, nor do they allude to how big it is. I can't imagine foot-long tentacles! There's always the chance that they're extending that far just because your tank is relatively empty, and they may be inhibited when you start adding things...


Oh, I just thought to look in my "Invertebrates: A Quick Reference Guide" by Sprung--it does have a little more info:






Region: Indo-Pacific, Caribbean


Description: transparent flat amorphous and highly mobile, these delicate creatures unfurl two extremely fine elongate tentacles into the water to trap planktonic food. The tentacles collapse in an instant into an apparent tangle and then just as quickly unfurl in neat perfection. Fascinating to watch. Able to swim with flapping motion. Harvested incidentally with soft corals (especially Sarcophyton spp.) and with algae, (especially Caulerpa spp.). Coeloplana astericola occurs with the sea star Echinaster luzonicus.


Similar: May be confused with flatworms.


Desirable/Undesirable Features: Ornamental. Reef-safe.


Food: Carnivorous. Feed marine snow and tiny zooplankton.


Special considerations: None.


Hardiness in captivity: Growth and reproduction. Life span-months-years.



There's a cool looking picture of a swimming one, and 4 pics of them associated with softies or starfish. Apparently they co-exist well. (pp 80-81)



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Hey, one more hit! From Marine Invertebrates, by Ronald Shimek:


Astricola spp., Coeloplana spp.


Sessile comb jellies


Maximum size: Individuals to about 1 in. (2.5cm) long.


Range: All tropical seas.


Minimum Aquarium Size: Small tanks, 10 gal. (38L) or larger.


Lighting: Immaterial.


Foods and Feeding: Must be fed foods such as enriched baby Artemia, along with occasional feedings of adult Artemia.


Aquarium Suitability/Reef Aquarium Compatibility: Good reef aquarium animals. Rarely become overly abundant. May irritate corals or other sessile invertebrates.


Captive Care: Even among the oddest of the invertebrates, these are rather bizarre animals. Most comb jellies (ctenophores) are wholly planktonic, although one small group has sessile adults. They look like flatworms with elevated ridges on their upper surfaces that may appear to have been outlined with a very fine white or colored pen. They are introduced to aquariums on their host (e.g. sea stars, soft corals, gorgonians, sea urchins). They feed by extending two fine hairlike tentacles into the water column and become instantly recognizable as ctenophores, as they have branched or fringed tentacles. If the tank is well fed with small planktonic foods, they may persist or even thrive.


(p 197)



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Wow, that's better than any answer I ever could have expected. Thanks for all the work. I guess I'll let this little guy stick around.

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