 Many species also have a number of short appendages on their abdominal segments, but the most distinctive feature of the group is the presence of three long, tail-like filaments extending from their last segment.These three generally subequal, except in some members of the family Nicoletiidae, in which they are short, and the cerci are hard to detect.The two lateral filaments are the abdominal cerci and the medial one is the epiproct.