Coralline eating starfish???

[Sahin]

I saw this starfish and a few smaller ones a few weeks ago.

He is about 1cm and stays on one position of live rock for long hours.  I found three others and have taken them as prisoner at the moment.

 

After he moves away, the area under him looks very pale white and looks eaten away.

 

Here is a pic of one rock this particular starfish has damaged.  All the white areas are damage due to him.

I dont see them anywhere except the rocks covered in coralline algae.

I have drawn green arrows on some of the spots he damage so far. (the shrimp decided she wanted to star in the pic as well )

 

Has he been caught red handed?  Or is he harmless to my coralline algae?

I am thinking its the former.  I rounded up the rest of his buddies and they are in prison at the moment.

 

Let me know what you think.  Thanks.

 

(Edited by Sahin at 12:17 pm on July 3, 2002)

[tinyreef]

looks like a sea star.  you can keep 'em or lose 'em.  i'd keep them for diversity in the tank.  it also depends on how fast the coralline is spreading or receding.

 

four's quite a bit though for a nano.

[eferna]

any reason why you were keeping star fish in a nano. I remember you has some problems with your star fish before sachin. They dont seem to be doing good in smaller tanks.

[Korbin]

Quote: from Sahin on 12:15 pm on July 3, 2002[br]

He is about 1cm and stays on one position of live rock for long hours

Maybe the corraline is just dying where he sat for so long because it wasnt getting enough light.

[NaNO ReeFiN]

That's very weird... I don't think the coraline died due to not getting light for long hours... I've had rock that didn't get any light for a couple of days and it was perfectly fine. I hope someone can clear this matter up cause it sure is interesting...

[Mr Spam]

thats very intresting.

[tinyreef]

according to sprung & delbeek, 'sea stars' (as they called them) are usually just LR hitchhikers.  that's if they're even sea stars, those colored tube legs are throwing me off a bit.

 

the coralline's not going to die from a few hours or even days (weeks?) of inhibited light.  those stars are probably eating it although i don't remember references that they do.  although hermit crabs will.

 

(Edited by tinyreef at 2:27 pm on July 3, 2002)

[Sahin]

The problem with the other starfish is entirely differant.

 

I too am very confused with this latest occurance.

 

I have live rock that at some point had been covered by a coral or other rocks for days and didnt lose any coralline algae.  This is something very different.  Now that the lights are off, I can see a stark differance in the areas the little starfishes had been.  These areas look eaten and VERY pale white...its like a layer has been dissovled away.

 

REMEMBER the size of this species is VERY SMALL.

So far the biggest one I have found is only 1cm, the others are much less.  They hitched on LR btw, I didnt buy them.

 

I guess for diversity I can leave them there but the damage by one starfish on a particular rock is just a little too much.  

 

Anyone can shed some light on this?

[grantlaw]

I haven't kept any tropical sea stars before, but I know a little about sea stars in general.  First of all, I have never heard of any sea star that wasn't carnivorous (voraciously so!)  I once observed  a group of Pisaster ochraceous feeding on a dead cat!  Many sea stars feed by everting their stomaches -- perhaps your stars are everting their stomaches onto the rock to digest inverts and your algae is being damaged as a result?  I suppose that would be cause for concern.

 

There are many studies which have shown sea stars to have a positive effect on diversity (by controlling populations of dominant competitors), but in a nano, they may just be a nuisance.  Perhaps keeping one or two might be fun . . .

 

At any rate, they look just like sea stars of the genus Leptasterias -- if they are, they would probably make great tank inhabitants as they brood their eggs which then hatch into miniature stars (no larvae to get tore up in the pumps!)

[Korbin]

If they were eating my precious coralline algae, I would give them the boot!

[Fant]

Id take em out. If they are brooders like someone else said, you could have a serious problem in the future. I cant think of any benefit of keeping them, except if you like nice white rock

[jdiver]

grantlaw- Maybe I don't want to know, but how on Earth did a dead cat come to be food for sea stars? :conf: :conf:

[tinyreef]

yeah, grantlaw, what kind of nano ARE you keeping anyways? :devil:

[Cam barr]

hey just picked  one off my LR in the 40 looks exactly the same. be carefull be cause they can devide them selves and do eat coral too. great article and pics at the garf website from what ive seen and  heard there are sevral speces and they all can do damage

cam

[Sahin]

Thanks Cam!  You are very right about dividing themselves...I didnt mention it as I wasnt sure and thought I'd sound stupid.

 

But I have seen and caught some that kinda look like one starfish cut in two.  Ie some have two legs and others have three legs.  

 

I have decided to take out any that I see.  

I took all I saw yesterday and kept them in a bucket so if I found out they arent harmful I'd put them back into the tank.  SO it looks like none of these buggers are going back into my tank!

 

Grantlaw; you are right about them everting their stomaches...yesterday I put a small piece of rock over some coralline algae for the whole day and oberserved later on that the lack of light for those hours didnt bleach the coralline algae.

 

Thus the starfish must be utilising some kind of stomach acid to disolve the coralline beneath themselves.

 

Well, thanks to everyone for thier help.