Blue Linckia laevigata Agat - eating my blue sponge?

[cryptodendrum]

In Aug 2005, we added a Blue Linckia Laevigata Agat to our tank. Although we took care to acclimate him well, he did start to MELT two of his arms for about a week, before stopping and getting better. His arms are now healing well, and he is looking almost twice as fat as he did when we got him now.

And now I wonder if I might know better why.

Today, as our fish were ending a 11-week long Hyposalinity treatment, and were being moved back to the main tank from their Holiday-Hypo-tank, my wife and I found ourselves observing and taking pictures of our Blue Linckia parking itself on top of two different blue sponge fragments - which were doing well up to today. After a period of about an hour or two on each, it moved off to reveal what appeared to be bare sponge skeleton where her orifice had been.

Is it really Feeding? Does anyone know?

I have quite a bit of sponges in my tank, which might explain his rapid growth?

This is just one of many in a sequence of photo's revealing this behavior and decimation to our blue sponge frags. If anyone's interested, I'll post them.

 

[racrumrine]

Since it has generally been considered unknown what this sea star actually eats, if you can confirm that it eats blue sponge, that would be great.

Keep making your observations and report back to us. Hopefully, it will eat more than one type of sponge.

How much live rock do you have in your tank? Usually, people recommend having at least 100lbs to keep one of these star fish (but, they still can't tell you what they eat).

Do you run a protein skimmer on your tank? I have heard that sponges grow better in tanks that don't have them.

Best of luck,

Roy

 

[cryptodendrum]

I would guesstimate well over 100lbs of live rock in our tank. I do run a protein skimmer, fresh carbon only occasionally in small amounts, but feed the tank quite heavily, keeping all my fish kinda fat. Corals, as do the sponges, seem to appreciate that as well with some impressive growth rates.

This morning, the Linckia revisited the sponge indicated with the orange arrow above, and left it further decimated. There's clear skeletal structure waving in the currents after parking on it for only an hour.