Anyone heard of these eating zoas?

[jasper24]

So I have been battling a zoa predator for the last couple of months. I have dipped in lugols several times and nothing but pods fell off. I caught a couple of baby snails on a colony once but it appears that they were just harmless algae grazers. Last night I noticed a small colony eaten and closed up. I pulled it out of the tank into a bowl of tank water and there was a 3 legged astrena (SP?) star covering the top of a zoa polyp. It was one of the darker bluish grey ones not the white ones that clean the glass. The polyp that it was covering is now missing its skirt. Anyone ever hear of these guys eating zoas?

[twon8]

I have seen them on zoas, but i tend to believe they only clean up the mess from a dead/dying zoa. i could be wrong though.

[ecotoxlady]

Yes, I've caught asterina's eating my armageddon's when I had them. Unfortunately they did so much damage to the armageddon polyp that by the time I discovered what it was doing the majority of the polyp had been eaten. I think they are an opportunistic predator that will ususally eat other things in the tank but on occasion will feast on zoanthids. Since my discovery, I do the best I can to remove all of them. A while back I sent a picture to whodah of the asterina in the process of eating a zoathid but don't know if he decided to use the picture or not.

[surfnvb7]

its possible, but not probable. according to dr. ron, (the invert expert), there are literally thousands of different species of those tiny star fish, and out of those, there are like 1 or 2 species that will munch on corals. and on top of that, its just about impossible to tell the difference b/w all of those species to the untrained eye.

if you want to be on the safe side, just remove the culprit, which is what i do if i see one that looks different or getting too big. you can also do a dip if that makes you feel better, it will not harm the zoas.

only thing i would look out for is if you are having massive die off issues, not just a couple polyps. that would be a red flag as to something going on.

HTH

[jasper24]

I have removed it. I agree there are lots of different types of these stars. The white ones I leave alone as they are always on the glass. These darker ones are always on LR or coral which leads me to believe that they are up to no good. I never see the darker blueish/grey ones on the glass.

[yoshiod9]

i do it the safe way, take them all out and put them in the 'banished' tank. i have all the corals/fish/inverts that caused problems (or that i just don't care for) in that tank. works well for me.

[whodah]

i've seen them at the very least 'agitate' zoas to death. don't know if they're eatting them or not...

but i have a hard time with floridian zoas. (and so do a few other west coasters i know) they seem extra fragile for some reason.

at any rate, i've had asterinas (don't know what kind -- as mentioned before there are 1000's of different ones!) suction cup on polyps and stay there for hours. next day, that polyp is gone. they've wiped out entire blue and other fragile floridian morphs in my tank.

i keep coming back to the floridian point because those are the ones they seemed to effect. i never saw them suctioning onto other varieities in my tank. then - i took action and got rid of them from my reef tank. (i did what yoshio9 did - into the FO they go! heck, they're cleaners in there at the very least, heh!)

ecotoxlady - i remember those pics... for some reason, i never added 'em! do you still have 'em somewhere? i cannot find 'em... sorry bout that, i meant to!

[jcm1229]

I also have had mysterious deaths or recessions on some zoa colonies. I've alway found these asterinia stars there, but I too thought they were "cleaning up".

I'm a beleiver that they may be causing the problems as well. I pulled out a small retracted colony last week and did a dip and found many pods, a small bristle worm, a mini briitle starfish and an asterinia. NO nudis, sundials or other predators.

[Creetin]

I have them stars all over, and if you see one youre mostlikely have dozens of them.
I have never seen them bothing any of my zoa's. They graze on algea.IMO

[jcm1229]

This was posted on Dr. Ron's forum:

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Haven't posted in a while, but check semi-regularly and this thread caught my eye.

Why? Well, here's the thing... yeah, I have Asterina in my tank. No, they don't eat Stonies, not that I've observed. BUT, if I introduce Zoanthids... gone, in a matter of days.

Slowly some of the Stars will approach the polyps. MOST of them don't, but some do. Of the ones that do, most have at least some orange coloration to their upper surface. It seems that all of the individual stars that have this orange speckling will consume the polyps if they can get to them in time. The polyp predator will make it way to an individual polyp, climb up the side to the "top", and place its mouth over that of the polyp, effectively appearing to be just a closed polyp unless you get close. Once the polyp is consumed, which may take hours to days, depending on relative size, it's on to the next one. Prior to acquiring a free frag a few months ago, the tank had been zoanthid-less for almost a year. These Stars do not not bother Palythoa or Protopalythoa. Neither do they molest Soft Corals nor Stony Corals that I have seen. In fact, no cnidarian other than Zoanthids seem to be on the menu. Now, I'm perfectly content to forego zoanthids, but what I really want to know is what I have here. Is this just odd feeding behavior/preference? Or do I have some weird and unknown species? I'd be glad to provide samples to anyone interested as long as they provide the "bait" to be assured of getting one that does consume the polyps.

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The sum of my knowledge is great, the sum of my ignorance greater still

Kieron Dodds
Administrator
Tropical Resources
TFH Magazine's Official Web Forum

[whodah]

very nice quote to reference! thx jcm1229!