What is this?

[Tinman]

Hi,
I seem to have a hitchhiker in my tank. I have a 34 gal Red Sea aquarium with 35 lbs of live rock and 20 lbs of live sand. My tank has been up and running for about 6 months now. I have no fish in there at the moment, they are all in a hospital tank and have been for about 2 months. I had an ich breakout that is gone, just waiting for the tank to be 100% clean before I put the fish back in. In the meantime, nothing new has been introduced to the tank.
Here is my problem, I have an assortment of corals in my tank, some snails, some hermit crabs, 3 shrimp, a tuxedo urchin and a pink tip bubble anemone. I looked in and I can see all these little white slug like things on my star polyp and my stars are no longer coming out. The slugs disappear at night but during the day they seem to linger on my coral.
Any ideas of what these are? They are about 1/2 cm in length, all white, 2 small black eyes or eye stalks, triangular in shape and when they lift their fronts up, it looks like a sucker or mouth underneath. Hard to tell though, they are very small.
I have attached 2 pictures as best I could but they are very hard to see.
My guess is that they are a type of sea slug or nudibranch and that they are eating my coral.
So, two questions, one, what are they? and two, how do I get rid of them since I think they are eating my corals!
Thanks,
Mike

[zhenya]

Hi Mike,

I can see some type of white things on the rock but I can not distinguish what it is exactly. Can you syphon one or two out of the tank into a small petri dish with taank water and try a close up shot then?

I'm just guessing here but it may be some type of nudibranch, hard to tell with the picture you provided.
You can browse www.seaslugforum.net in the meantime to see if you can find something that match what you've got.

[Ninong]

Are the "two small black eyes" on the end of the "eye stalks" or are they flush on the 'head' of the animal?

I would expect that they should be on what passes for the head and not on the end of what you are describing as "eye stalks."

Can you remove one or two of them carefully without destroying them in the process so that you can take at look at them with at least a two-power magnifying glass? Be sure to keep them in tankwater while removing them so that they don't collapse.

Do you see any cerata? These would be appendages sticking up from the dorsal area of the animal. The "two small black eyes" should be on the front of the body but not on "eye stalks." The two stalks mounted on the 'head' of the animal are all-purpose sensors.

All of the above assumes that Gene and I are correct in assuming that what you have are aeolid nudibranchs. Aeolids are carnivorous, as are all nudibranchs. They are usually specific in their choice of prey. For example, some eat only Montipora species and others eat only zoanthids. However, there are so many different species of nudibranchs that I guess it's possible to find some that will eat something in your tank that you would rather not be eaten.

After you have examined one or two of these nasty little beasts under a magnifying glass, tell us what you see and then we can tell you how difficult it is to get rid of them. If you don't see any cerata on their backs, then they are not nudibranchs. They we have to start guessing all over again.



P.S. -- Gene, I have my monitor set on 200% and that seems to work. My monitor is a widescreen job and 200% fills the screen exactly.

[Tinman]

Hi Ninong and Gene,

Thanks very much! I caught one in a cup and took a closer look at it. It is white on the bottom, the back is speckled and seems to be light green. The cerata, would they look like it has ridges on either side of the back, they would be raised and I am not explaining this very well. I can't get a focused picture of them either, I have tried three cameras. I am now going out to buy a magnifying lense to get a better look as well.
I'll update as I get closer to exactly what they are but there appears to be about 40 of them in the tank at the moment.
The eyes are on stalks, not flush to the head.

Thanks again!

Mike

[Ninong]

Gene,

If the eyes are on stalks, that would rule out aeolids, right? I don't feel like googling for that right now but I believe aeolids have eyes on the head, not on stalks. He is describing cerata though, so they're probably some sort of nudibranch, right? I'm just confused by eyes being on the end of stalks.

Look that up for me if you don't know if already off the top of your head.

[zhenya]

George,

You are correct. The eyes are never on any "stalks" in true nudibranchs, including the aeolids. Those are simply the antennae like you said and they may have some sort of dots on them but wouldn't be eyes. At least I don;'t believe so. I'll Google some later on to make sure but right now I'm off to eat my lunch.

[Ninong]

Gene,

Okay, that's what I thought. I knew that aeolids didn't have eyestalks but I wasn't sure if that was true for all nudibranchs. I had a suspicion it was but I guess I hadn't given that any thought before. The antennae are all-purpose sensors but they don't have eyes on the tips like strombids. Obviously he doesn't have strombids. I was just using that as an example.

Anyway, based on the small size and the number of them in his tank and their observed behavior, I'm still leaning towards nudibranchs of some sort. All of them, with the exception of Aiptasia-eating Berghia, are bad news. They're eating something in his tank or they wouldn't be multiplying. And since they're all carnivorous, they're almost certainly eating something he paid good money for.

Waiting for a more detailed, close-up description.

[Ninong]

Mike,

We don't really need photos. Just try to get a really good look at the head. You should be able to see two eyes eye spots on the head, not on the ends of the antennae.

With the exception of "eyes on eyestalks," you are describing an aeolid nudibranch, which is not good news.

They can be removed manually but that's not an easy job. Affected corals can be removed (if practical) and dipped but that's not an easy job either. And you will usually never get all of them. The ones that remain will continue to multiply.

It is difficult to treat for these in the display tank.

If they really do have eyes on the ends of eye stalks, then I'm at a loss right now.

[Tinman]

OK, so I bought a toy portable microscope to get a better look at this thing. Gotta love toy stores!
The stalks are not eyes, but black tipped antennae. The eyes are on the heads. The back is yellow with brown streaks on it. Basically it looks like a slug. The underside is white and the mouth is at the bottom.
Would a wrass eat them? I have a 6-line wrass that I could add back into my display tank. I have been ich free for 10 weeks, I just wanted to give it another 3 to be safe, but I think it should be fine. I tend towards more cautious than anything else nowadays.

[Ninong]

What you have described, provided it does have cerata on its dorsal side, is a nudibranch, probably an aeolid nudibranch. I don't know of anything that will eat them because they are toxic.

The standard recommendation is manual removal, which can be a big pain. I have heard of some people having success removing the ones that are on individual corals that can be removed and dipped by dipping the affected corals for 15 minutes in one liter of tankwater that has four drops of Flatworm eXit in it. If you need more than one liter of tankwater, then just increase the number of drops of Flatworm eXit proportionately.

After allowing the coral to remain in the dip for 15 minutes, shake the coral upside down vigorously for at least a minute or two before transferring it to another bowl with just plain tankwater. Shake it vigorously upside down again for another couple of minutes to remove any that are still on it.

I don't know if that really works or not but even if it does work, you won't get all of them out of the tank. If you can figure out which species (or at least genus) of coral these little beasts are feeding on, then removing those corals will result in the aeolids that remain in the tank starving to death. Most nudibranchs are quite specific in their choice of prey. If their prey is not available, they starve to death.

Maybe Gene has some suggestions on how to get rid of them.



P.S. -- Gene, they keep interrupting the football games to tell us we have a Category 2 hurricane in the Gulf, as if we didn't already know that. Idiots! Stop reminding us every 15 minutes. Its winds are currently 100 mph but they are expected to drop down to 85 mph when it crosses the southeastern tip of Louisiana on a path taking it into Mobile. I'm only under a tropical storm watch right now, not a hurricane watch. Just the coastal areas are under a hurricane watch because the storm is still expected to curve to the east as it approaches the coast. I hope they're right.

[Tinman]

Thanks very much...Fortunately for me all my corals are still small, but that one was starting to spread. I should be able to pull it from the live rock and dip it. The part that I find really funny is that nothing new has gone into this tank for over 3 months now and I keep finding new things wandering around in it.
First it was a new kind of hermit crab, one that has black and white legs and larger claws, then it was a small tan colored crab that looks like an emerald crab but with the wrong color. I also have some large worm crawling around inside one of my live rocks, just not sure what that is. And now I have these little blighters in there messing with my corals.
Am I going insane or the more stable the environment becomes, the more things seem to appear.
Thanks again!
Mike

[zhenya]

Mike,

I hate to bring this to the table but I think the best solution for the problem at hand would be to remove this one coral where you have found these nudies. They are very specific as to what they eat and most of the time it is just that one coral that they came on. By the way, it could have been just a small egg sack that was under the coral and went unnoticed.
Once the coral is removed this things should starve out and should be gone.
Not sure how long it would take but I would wait few month before trying to introduce another colony of the green star polyps.
Problem in dipping just that one coral lies in that those nudies could have laid eggs already in a few places, but most of the time it would be right under that prey coral and surrounding live rock ( I mean few inches from the affected coral). If you have other corals mounted there then it becomes a real PITA to deal with the situation.
If you can part with the star polyps I would probably go this route of eliminating this pest's food sourse and waiting it out instead of killing an entire piece of live rock.

[Tinman]

Thanks very much for all the advice. I took the one piece of coral out and have suctioned out all the stragglers that I could find. I also suctioned out what I think was an egg sac, a spongy white ball.
I have the coral in a little plastic container, I hate to throw it out but it is infested, they are all through all the little nooks and crannies. I don't think i can salvage my poor little piece of coral.
I tried the dips and I even tried a fresh water dip, they removed some but there are still so many left.
Thanks again for all the help, I appreciate it.
Mike