Linkia, lost leg

[insguy]

My large orange linkia star left a leg hanging on the side of the tank two days ago. It was well up the side so I doubt anything could have bitten it off. It happened right in the middle of the day with the lights on. The leg was gone the next morning. Reef tank, small crabs only
Is this normal? what could have caused it?

 

[lnarobbins]

I don't know what may have caused it but if the leg is healing well it will grow back and the missing leg may turn up as a new starfish
just my opinion
Alan