When they returened the coin to the tresuser chest they all had to cut them self and but blood on the coin!!! My question is if there undead how do they have blood? When they are hurt no blood comes out???

When they returened the coin to the tresuser chest they all had to cut them self and but blood on the coin!!! My question is if there undead how do they have blood? When they are hurt no blood comes out???
You don't see any blood in the moonlight, but when the moonlight doesn't shine on them, they look like real people, and when they get hurt that have blood and everything, it jsut doesn't hurt them.

Remember when Elizabeth and Barbossa were in the cabin eating? she took the knife and stabbed him, and there was blood on the knife, but it didn't hurt him because he was cursed.

oh yeah i forgot thanks