What other fish/inverts are in your tank? Any new members to the tank? Is the starfish new to the tank? What kind of starfish is it?
The starfish leg(s) will grow back in time and the gash should heal provided it's not too deep and showing flesh.
am wondering if these wounds could be caused by my urchine?
A Starfish will try to eat sea urchins b/c it's a natural food source for them. I just came back from my LFS
and I watched a starfish grab a hermit crab in about a 2" shell and eat him (of course he was still snacking on him today when I went back there, lol).