Im sure this is a much asked question but, if a creature has improved grab and constrict (lets say they have a tentacle attack) then if they hit with a tentacle they get to try to grapple as a free action with no AoO, if the grapple is successful you establish a hold and can constrict. Then constrict says: with a successful grapple check do X amount of damage. Lets say you succeed on a grapple check against the target hit by your tentacle, and you establish a hold, do you do constrict damage immediately or do you have to make another grapple check? It seems that you get to do the damage immediately but I think its alittle ambiguous and could be interpreted both ways (since it says you CAN constrict, meaning you get the option to constrict, not you DO constrict).