Starfish ID, Reef Safe?!?!

[CraigLampe]

I just began to see these little guys popping up, wondering what they are, assuming they are (incompletely grown) starfish, but they look like the normal, non-reef-safe variety, I probably need to start flushing them, huh?? any thoughts?

each one is about 8mm across...

 

[investigator1]

If they are the little tiny small pure white ones.....then your ok.
If they are the little tiny samll striped ones...then your not ok.

 

[Anonymous]

A topside pic would be helpful. They look like a kind of sandsifting star, but it's really hard to tell from just the underside.

 

[iphy]

They look a bit ... um ... hairier than the ones I have, but that could just be the extreme closeup. Are they sort of mottled, sandy-coloured on the tops?

These things showed up in my 55 about 5 months ago (after a purchase which involved a live rock fragment). At first, I just saw something which looked like a piece of a tiny starfish, then I saw the other half of it on the other side of the tank. Those two kept splitting and splitting. At one point we actually got to witness the split as on of the little guys did his splitting right on the front glass.

Anyway, I watched them very closely, because they looked just like the things in Delbeek and Sprung's The Reef Aquarium (vol. 2) on page 433. Here's the note:

These small sea stars (Asterina sp.?) are sometimes found in reef aquaria. What they are and what they do is unknown. They reproduce vegetatively by fission and can become quite numerous. They are probably harmless algal and detrital feeders, but some species do graze on smalll polyped stony corals.

They appear to be eating algae; however, I don't have any stony corals. They do cruise the live rock, but they love the glass. They reproduced like crazy for about the first month. Lately their numbers have decreased and I have noticed a lot more "full" stars and a lot less fragments running around. Presumably, they've reached the extent of the food supply.

 

[Anonymous]

They look (from what I can see, anyway) very much like the seastars I saw in one of Walt Smith's "junk" tanks. Mottled on top, blending in very easily with the fine sandbed, appeared to be sifting through the sand. VERY numerous, as well. The biggest one I saw was no more than 2" across, and yes, I saw several that appeared to be "fissioning" (if that's even a word).

I would say, knowing how delicate many (if not most) seastars can be, that it's actually a testament that you've got a very healthy system set up there, my friend.

 

[wombat1]

Those look like Asterina all right. The description is exactly what I've heard too. I've seen them congregate on button polyps but no damage appears to be done to them. I think they feed on just about anything, and will eat corals as well if they get REALLY hungry. If they're asexually reproducing, that's probably not the case. There is a reef safe species of sea star, Nordoa sp., which eats them, incidentally. It will eat other foods besides these guys as well. I'm sure a harlequin shrimp would chow down on them as well, but it would be difficult to feed after it eats all of them. Greg Scheimer discusses the Nordoa stars in Advanced Aquarist.
http://www.advancedaquarist.com/issues/ ... allery.htm