sentence2_structure: aggressive type of displays<>are<>common<>in the animal kingdom$$$aggressive type of displays<>serve<>as a 'bluff<>sometimes
sentence1: Animals also commonly use aggressive displays to communicate the nature of their aggressive state to other individuals of their species.
sentence2: Exemplified by baring teeth, aggressive type of displays are common in the animal kingdom, and sometimes serve as a 'bluff'.
question: Exemplified by baring teeth, what type of displays are common in the animal kingdom, and sometimes serve as a 'bluff'?