Is your idea that the starfish will regenerate its legs and then you can keep feeding it the same starfish? I am not sure that that would work for all starfish or how many starfish you would need depending upon the rate of regeneration. Futhermore, were would you make the cut as to not mortally wound the starfish? I have seen them eating linckia, I am informed that they eat these as juveniles. The adults are known to eat asterias. Finally, I might look into if there are any conservation issues regarding linckia...I heard quite a few people are killing these.