Are Emerald Crabs a threat to starfish.

[TWYOUNG]

I recently added several Emerald crabs to eliminate some bubble algae. Although they quickly eliminated this issue I now have seen them fighting with each other and grabbing at fish as they swim by. Today I noticed the tip missing from one of my Sand Sifting Starfish. Could the Emeralds be responsible?

 

[jabberwock]

If its got claws, it breaks laws...

Except for porcelain crabs. Porcelain crabs are cool.