Once they are tamed they will attack guild/ally members and any other people that happen to come in contact with them. I was just hanging out in the ship waiting on others to show up so we could kill the boss. Once a guildy came into the area both of them immediately attacked her as she fell down the water fall. I figured I had made a mistake and targetted her or something. Then as she was clearing the rooms while we waited a blue came in. Both of the crabs were at wonderfully happy and went after him as well. Also, they on occasion even flag me. My taming/lore is 110/110.