Cirratulus cirratus is a species of marine polychaete worm in the family Cirratulidae. It occurs in the littoral and sub-littoral zones of the Atlantic Ocean. Polychaetes, or marine bristle worms, have elongated bodies divided into many segments. Each segment may bear setae (bristles) and parapodia (paddle-like appendages).

Cirratulus cirratus is a species of segmented worms in the family red threads worms. They are surficial modifiers. They are facultatively mobile animals.