Brittle star growing from a lost tentacle

[tormented]

Yesterday I noticed one of the black brittle stars legs sitting in the from of the tank, and its still there today, and still moving. Will it turn into a new starfish?

 

[ophiura]

No. It will continue to move, but needs quite a large part of the central disk of the animal to even have a shot at regrowing. This is not typically true of brittlestars.
I would look into why the brittlestar lost the arm. This is often a sign of stress or other problem.

 

[tormented]

I cant think of a single reason that would cause my 2 stars any stress. I cant even tell which one it was that shed the limb, they are both hidden too well. They do seem to be in the same spot, could that be it? They had a fight, maybe?
How long before I can tell if I am growing a new star?

 

[ophiura]

No, they commonly occupy the same areas in the wild. I don't think that would be it. Could be even something like a crab grabbing the leg. That is what happens.
I highly doubt that it will regenerate anything. It would take several weeks at least to know I should think, and months and months after that.