predatory starfish?!

Hello

It seems I have a predatory starfish on my hands.  I bought the dang thing with the assurance that it was a peaceful sand sifting sea star that would help churn sand and eat detritus, but so far it has gobbled up a snail and a hermit crab.  Here is a photo of the starfish bulging from enveloping the crab, shell and all:
http://tinypic.com/edcth

What I want to know is:
1. Is this REALLY a sand sifting sea star?  The pattern of bands of color is the same, as is the size and shape (it's about 3'' in diameter), but this one's pink and brown whereas all the pics of sand sifting sea stars I have found depict them as white and gray.

2. Does anyone have a predatory starfish?  What are the +'s and -'s to having one?  What is safe in the tank with this guy?  I want to know if I can own any other inverts with this guy lurking just beneath the sand's surface, looking for his next victim....

The lady at LFS, when I told her about the snail, said that the starfish physiologically couldn't get the snail shell into itself.  Well, that picture shows differently!  I dug him up and, yup, the shell is INSIDE him.
Poor little hermit crab, he never hurt anybody, all he did was eat algae and dig little holes....
[smiley=bawling.gif]

 

Hmmmm, what else would be safe with that star....hmmmm

IT ATE A HERMIT CRAB....SHELL AND ALL!!!!

I think that says it all.

LOL (not funny I know) but I have NEVER seen such a thing! That is just really too bizarre! Sorry I don't have any info on the stars but if it were me....he'd be toast! Back to the Store! Or in the sump/fuge if you have one!

 

Aye
I can't believe he ate the whole thing, lol! Right now I'm planning on trading him back to the store for 3 hermit crabs--they're pretty good about that sort of thing.

I wish I had a fuge...This is my first SW tank and I'm still learning stuff all the time. Things like, um, invert compatibility.............

And yet...and yet he's kind of cool. I'm half tempted to just throw him in his own little domain and let him grow. The LFS had a much larger one and internet info suggests that sand sifters can grow quite large. That could be fun.

 

Does it have an orange mouth? Is it purple?

 

Very cool. I have a large Green Brittle star that I gave seen attack a hermit. I had just fed the tank some frozen shrimp and you know how thes inverts get when there is fresh food in the tank. The hermit got away. I think the star was just trying ti steel the hermits food find, but he did have the crab all the way up to its mouth.

Jay

 

Green Brittles are a bit more predatorial than the blacks....

Here is an article on the predatory nature of stars...
http://www.reefkeeping.com/issues/2002-04/rs/

And I think this one looks more like yours that the pics of "sand sifting stars" but I am by no means a pro at this! Yours looks a little spinier than pics I 've seen of other sand sifters.


http://www.scuba-equipment-usa.com/marine/MAY04/Comb_Seastar(Astropecten_polyacanthus).html


I still cannot believe he ate your hermit crab...he ate a snail too right?

Where is Gresham? He is really good at IDing things... ;D

 

"This species a lot of time buried below sandy silty bottoms in ... is best recognised by the dark purple upper surface and the orange colour underneath"

That describes it to a tee! And the spines...by jove, you've done it! You've actually ID'ed my sea star. I'm positive that's what it is.

Something I noticed is that that site labels it as A. polyacanthus, and a sand sifting star is A. polycanthus. Pretty close--not a typo, I think? The "a" in polyacanthus must be significant. "Many-NOT-canthus" as opposed to "Many-canthus".

 

I did a google search both ways and get pretty much the same results...looks like a typo or interchangable terms.

They also seem to be referred to as 'sand sifting stars'...apparently a dubious nickname because it sifted your hermit crab right out! >

 

aye, i found the same thing.
one site said that members of the Astropecten genus are difficult to differentiate.

 

i dug up the starfish today and the shell was under him in the sand. i pulled it out and examined it--no hermit crab. i took a sniff and it STUNK in there, whew!