FAQs about Live Rock Hitchhiker/Creature
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Hitchhiker ID 9/7/09
I'm trying to ID something in my tank that showed up on a
piece of live rock that I recently purchased. I've been
searching for a while trying to figure out what it is with no
luck. It kinda looks like aiptasia but I'm
not 100% sure and wanted a second opinion.
<Not aiptasia, but appears to be another type of small
anemone, Bob may accurately ID here.>
Also there is some white stuff kinda behind it that you can see
in the pic.
Is that some type of sponge? I've never seen anything like
<Yes, likely a Clathrina specie of sponge, commonly called a
Thank you in advance for your help.
<You're welcome. James (Salty Dog)>
please help me tag these 8/30/2009
<G' morrow Mr. G.>
I Googled long and hard trying to identify what this white
cotton-like, flat hairy film is on my live rocks. I thought you
might be able to help me identify them so I know what these may
be symptomatic of. I hope the pics are clear enough for your
<These are Sponges, Poriferans... evidence of system stability
and good husbandry on your part. See here:
and the linked files above.
Re: please help me tag these
that's good to hear. now i can rest in peace. ;p thanks
p.s. your site really is a great help to us neophytes. thank you
<Ahh, welcome Jope. BobF>
Weird Creature In My Reef Aquarium... Maybe a Spaghetti
I have tried to research this as much as possible, but I still can not
find any information as to the identity of this "thing" I
have in my aquarium.
<Ok, let's see if we might figure out what this
It came in a piece of rock with Zoanthids that I bought. It lives
inside what appears to be a calcareous tube, about 1 inch long; 1/8
inch diameter. From this tube it protrudes a white "sort of
mouth", and 2 small white tentacles. It has two kinds of behavior
I have seen. (1) it sends several threads that look like the strands
a spider web, which attach to rocks. They are quite long (5-6
Little particles become stuck to the threads and every once in a while
the "thing" begins retracting them into its mouth. (2)
Usually a few minutes after the threads have been completely retracted
into the mouth, the mouth inflates a bit, and expels about 6-8 little
green "dots" that appear to diffuse away in the water. Any
ideas what this is?
<Sounds like a Polychaete worm of some type, possibly a Spaghetti
worm (Terebellidae spp.) A picture might be more helpful. It is not
something I would be worried about. Is likely a harmless filter
Thank you very much. I am SO curious to know.
Unknown Critter..can you help me out
First time post here...Let me just say first that your site has
provided me a wealth of information over the years.
I recently (about 6 months ago now) started up a reef tank again
(I had one going great when living in St. Pete FL but moved to
Ohio 2 years ago to start Ph.D. work so I had to get rid of
everything to make the move easier)...anyway...as I was saying, I
started up again as I could not go without the beauty of reef
tank (... it certainly helps relax me at the end of a school
day!!) and everything appears to be doing ok...I really just have
a quick question about this critter(s) that came attached to a
piece of live rock and has been getting larger. I attached a
pic...I want to say that it is a mushroom coral of some sort (or
not..lol) but it appears to have several 'mouths' which I
have circled here in yellow. They are not as prominent in this
pic but throughout the day each of these 'mouths' open
and extend the tentacles that surround them...I've looked WWM
up and down yet I am still at a loss...if you could help me out
that would be wonderful!....Thanks in advance!
<I can't quite make out much detail in this pic (am out
traveling and my laptop may not have sufficient
"pitch"/resolution, but this might be a combination of
organisms... Perhaps a sponge with hydroids or other life living
inside its body cavity... Would you please send along a larger
file of better acuity? Bob Fenner>
Re: Please help with fish i.d.?/Now Algae ID
Hi again. Haven't seen the mystery fish since I last emailed
you - occasionally I see a flash of sand as something bolts into
the liverock when I enter the room, I assume this is him (or some
other hitchhiker?) fleeing at my approach.
Anyhoo, wanted to get your opinion on the algae in the attached
pictures (I'm referring to the feathery, wavy stuff).
Cause for alarm?
<Not at this stage.>
It's spreading fairly quickly but not at an alarming rate; I
don't know if the 3 Ceriths or 2 scarlet reef hermits (which
I now know shouldn't have been added at all) are eating it.
If it helps, tank is about 3 weeks old. I've looked through
the algae i.d. FAQs but can't seem to match it up to anything
<I couldn't find any exact matches myself, but I'm
guessing it could be a type of
Caulerpa or possibly Crouanophycus latiaxis. Bob or another crew
member may be able to ID it.>
<You're welcome. James (Salty Dog)
| Umm, wrong Kingdom James. RMF
Please Help With Fish ID/Now Algae ID
"Umm, wrong Kingdom James. RMF"
Thank you, but remember, I did say I'm guessing.
Better for me not to answer ID queries if I cannot provide an
accurate answer, keeps me from looking like a fool.
<... Don't respond to queries you don't feel qualified
to respond to my friend... helps no one. Think of "Asparagus
Ferns" in this case. I don't think this is a
Are you all burnt up yet in the Florida sun? A cold longneck just
has to taste good after a day of diving.
<Oooh, now you're talking. BobF>
Hitchhiker ID: Rock-Dwelling Sea Cucumber --
<Hello Elfrieda, Lynn here today.>
Another puzzler for me....6 months into the set-up of my 24gal
Aquapod w/ metal halide light. It appears to be some sort of worm
<Actually, what you're seeing is the feeding apparatus of
a rock-dwelling sea cucumber/holothuroid. For more information,
please start with the FAQ's titled 'Please help to ID:
Sea Cucumber -- 6/1/09' and 'Anemone Id? Nope, It's A
Cuke! 8/10/07', located at the following link:
http://www.wetwebmedia.com/cukeidfaqs.htm . Please also note
links within the two FAQ's.>
The second time I've seen it on the same rock....and the last
picture is just before it disappeared.
Thanks so very much for your time.
<You're very welcome>
<Take care, LynnZ>
Re: Hitchhiker ID: Rock-Dwelling Sea Cucumber --
Another look at this stranger....
Its tentacles appear to be catching food and one by one are drawn
into its 'mouth'.
<Good observations - that's exactly what it's
<You're very welcome>
<Take care, LynnZ>
<<A nice short video clip... that RMF doesn't know how
to add to WWM...>>
Thick Brown Tubes Growing From Live Rock
Your site has been a wealth of information, thank you so much.
It's been a good 12 years since I maintained a small 20
gallon reef aquarium in CA where I did water changes with sea
water and enjoyed all the surprises that came along with it
oftentimes. This year, as I embark on setting up a reef tank once
again, I find there is so much more knowledge about reef systems
and it's wonderful. I am having so much fun reading all the
information online and learning so much.
I have an identification inquiry about some thick brown tubes
that have grown from a piece of live rock covered with Star
Polyps in my reef system.
<Are sponges of some sort... a burrowing variety/species...
Any input is greatly appreciated, thank you!
<Welcome. Bob Fenner>
Re: Interesting Hitchhiker: Pseudocorynactis,
Hydroids, Foraminiferan -- 6/14/09
Lynn and company,
<Hello Roxanne, Lynn here again.>
Thank you so much! That Pseudocorynactis is really nice;
there are more of them each day. They are indeed nocturnal; I
should have mentioned that.
That sort of proves that I did not indeed get all Fiji rock
Since Pseudocorynactis is from the Caribbean,
<Yes, and the Indo-Pacific region as well. See the following
link for photos of Pseudocorynactis spp. in the Philippines:
hmmm, so much for LFS ID's on rock!
<They could well have been right!>
Do I need to feed them at this point?
<Probably not -- especially if they seem to be
As for the little unknown things I call hydroids, I have attached
a picture; it's the first photo ("hydroidperhaps). There
are 2 in the center of the picture. They are linear, no tube I
can see, and there are little dots along their length.
They are so small - I took a rather grainy photo to try to get
them in focus (they wave around a lot).
<I can see them and yes, those are unfortunately hydrozoans of
Are all hydroids "bad" in our tanks? I know they sting
(and especially me!), but other than that??
<Heeee! They're not bad if you want a hydroid tank!
Seriously, I would not want these in my system. The good news is
that sometimes they arrive on live rock and simply die out
without any intervention. The bad news is that sometimes they
don't. Hydroids can pack a wallop when it comes to stinging
livestock and people so you really don't want them around.
I'd go ahead and manually remove them with tweezers (or the
like). Also, be sure to keep your nutrient levels low, so feed
whatever livestock you have, sparingly. For more information,
please see WWM, starting at the following FAQ page:
Then there is #2 photo here; is this a filtering holothurian?
<Nope, it's a harmless little foraminiferan, a Protist
that feeds on particulate matter and possibly bacteria. Please
see the following links for more information:
Ignore the hermit crab. He was a bit of a mistake, along with his
few friends. They came with an order of other fun stuff from
which I mostly like. I didn't really want crabs, but
didn't have the heart to do away with them.
<Good. If they become a problem, you can always give them away
to a fellow hobbyist or possibly trade them for something at your
Thank you so much!
<You're very welcome!>
<Take care, LynnZ>
Hope You Can Identify: Syconoid Sponges --
<Hello, Lynn here today>
I am relatively new (2 months) to SW tank keeping and have a
beautiful piece of LR with a few mushrooms. I've recently
noticed that there are now several white fuzzy "stalks"
growing from the rock. They don't move or retract, just
slowly get bigger. I've also now noticed a few isolated
one's on other rock. Any idea what they could be?
<Yes indeed. They're harmless, filter feeding sponges in
the genus Sycon, also called Syconoid sponges or commonly known
as pineapple or Q-tip sponges. For more information/photos,
please see WWM, starting with the first FAQ at this link (as well
as related links at the top of the page):
I'm attaching a couple of pictures.
<Yes I see, thank you!>
<You're very welcome. Take care, LynnZ>