Polychaeta
plural noun
Poly·chae·ta
: a class of Annelida or in former classifications an order of Chaetopoda that comprises chiefly marine annelid worms usually having paired setate appendages on most segments, a differentiated head with eyes, tactile processes and bristles, and chitinous jaws and being distinguished from the related oligochaete worms by possession of separate sexes and by a complex life history with a free-swimming trochophore larva see errantia , sedentaria
Word History
Etymology
New Latin, from Greek polychaitēs with much hair, from poly- much (from polys much, many) + chaitē long flowing hair