hitchiking star (pics and ID help please!)

[cooksalot]

i was looking at my tank and all of a sudden noticed this star fish. i don't know where he's been hiding, but there he was and my nassarius and cleaner shrimp were very interested in him. also, this may be a dumb question, but i thought stars had five legs...he looks like he has three full legs and then lost a few and it looks like four nubs are growing. is this normal?

i know these aren't the best pics, but can anyone ID it and let me know if he's good or bad. thanks!

from the top (he's fast)

http://i39.photobucket.com/albums/e160/cooksalot4970/IMG_8497.jpg

from underneath on the glass

http://i39.photobucket.com/albums/e160/cooksalot4970/IMG_8490.jpg

will my nass try to eat him? he keeps crawling over him.

http://i39.photobucket.com/albums/e160/cooksalot4970/IMG_8487.jpg

[BurntOutReefer]

cool...good guys.

[Paintbug]

Asterina sp. they are usually good guys. great little algae eaters. the reason you see some full legs and some small one is a sign that it recently split into a new star. they will often drop on leg, or split in half to make a new star.

[papagimp]

Well, I'll take the other road and say bad guys, some species of asterina are known to mow down the coralline algae and occasionaly even zoo's and other polyps. I've got none in my tank for personal experience to share but all the reefers i associate with pull em out at first sight. If it's not hurting anything than I don't see a problem but remember as they are splitting and multiplying eventually there food source will run low and they'll find something to eat, possibly something you didn't want them to eat. Good Luck!

[cooksalot]

hmmm...thanks for the ID, and of course now he's gone, so no fishing him out now. i guess i'll keep an eye on my coraline and polyps (although my emerald crab likes coraline..grrr, so i won't be able to completely tell by that). i hope he behaves..i have always loved star fish, and i would love to have one, but in a 24G i know it's not a good idea, so maybe this guy will suffice :)

[papagimp]

I've got a few of the really small micro-brittle stars in a 2.5gallon grow out tank I have. There a little more reef safe, and very good "excess" food eaters. Might see if you can find somebody there who has a few. They don't look like a "typical" starfish but more like a serpant star. I like em though and they don't bother nothing in my tank. And if you seen one asterina in your tank, you probably have alot. There are many other reefsafe starfish to consider as well. I had two in my 55 for a long time, a green serpant star and a sand sifter. Gave the sandsifter away as a christmas gift but i keep the serpant around. he hides all the time eating what behind all the rockwork so i don't get to enjoy seeing him. Bummer!

[hawaiian_boi]

white ones good any other color bad

[greenbean36191]

I don't see a problem but remember as they are splitting and multiplying eventually there food source will run low and they'll find something to eat, possibly something you didn't want them to eat. Good Luck!
I did a bit of work with them a few years ago and even after months of starvation the ones I worked with still wouldn't switch to healthy or dying coral, or any other meaty food I offered. It seems like there are a few species that are predatory or at least opportunistic, but the majority seem to be pretty set in whatever it is that they eat (which I never did determine).

white ones good any other color bad
There is no way to tell the species apart short of DNA testing. The color is variable and can change throughout the star's life.