part of part_of sucker series The longitudinal rows of suckers on the arms or tentacles of decapodiforms. Series (= longitudinal rows) contrasts with rows (= transverse rows) in describing sucker arrangement. In octopodiforms, sucker "series" is generally synonymous with "rows", the "longitudinal" component of the term is implied. Suckers can form distinct, regular series or indistinct, irregular series. collection of suckers circumoral appendage