3 armed starfish, good or bad?

[scubaduderon]

I have noticed a number of small 3 armed starfish on the rock in my tank. I'm wondering if they are harmless or if I should attempt to remove them?

The largest is about the size of a dime, with the others about half that size. They are sandy colored with redish brown spots, but they blend in to well it is hard to distinguish.

They don't seem to be harming anything, but I'm startled to notice them all at once.

My LPS, SPS, zoo's and all other life forms seem to be ok. I even have several different kinds of sponges going along quite nicely.

As a matter of fact the tank life seems to be exploding with diversity as never before.

Does anyone know what these creatures are? It seems odd to me that they all have 3 arms. Is this just an example of a genetically inferior starfish multiplying?

Thank you,

Ron

 

[jski711]

not sure if they are good or bad but either way sounds like your tank is doing very well. good luck with that though

 

[paininthewrasse]

Astrina starfish. They reproduce by splitting so they have all different numbers of arms. I remove them from my tank as they can really take off.. IME they seem to eat coraline algea, other then that they don't mess w/ much. Like I said though I remove them when I see them as they can really take over.

 

[jski711]

wow same post time thats crazy.

 

[paininthewrasse]

we're awesome


Here is a photo of one. Not all of them have 3 legs.. it seems they have less legs when they just split..

http://www.sparklingfloorservice.com/melevsreef/pics/0105/astrina.jpg

 

[Pufferpunk]

Good detrius eaters.

 

[paininthewrasse]

Do a google search on them. Some say they are harmless some say they eat corals.. I remove them either way as they are an eye sore.

 

[jmicky41]

I had some and mine did indeed seem to eat coraline algae. When I found some on the rock and plucked them off, the coralline would be gone from where they had been sititing. From what I have read, some are harmless scavengers, some eat coral, and some eat coralline. Which is which is hard to determine. I seen a few lately, but will let them be as I have plenty of coralline now.