Comprising roughly 80 percent of the breeding population, large parental males, distinguished by their size, copper colored bars across the top of their heads behind the eyes, and silvery blues breasts that may turn yellow or orange during the spawning season, commonly manage bluegill reproduction.
large parental males가 주어이고 distinguished가 동사라는건 파악이 되는데요. 해당문장에서 문맥상 distinguish는 수동태로 쓰여져야 할것 같은데 be동사는 왜 생략되었나요? 아니면 제가 완전히 잘 못 파악하고 있나요?